Grasso R12 Overhauling Manual

Reciprocating Compressors for industrial refrigeration
GEA Grasso 12
Service Instruction Manual

0087123gbr_5
Service Instruction Manual | GEA Grasso 12
COPYRIGHT
All Rights reserved. No part of this publication may
be copied or published by means of printing,
photocopying, microfilm or otherwise without prior
written consent of Grasso.
This restriction also applies to the corresponding
drawings and diagrams.
LEGAL NOTICE
This publication has been written in good faith.
However, Grasso cannot be held responsible,
neither for any errors occurring in this publication nor
for their consequences.
2 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

SAFETY INSTRUCTIONS
Hint!
This manual must be carefully read
and understood prior to installing and
servicing the compressor (package)
General Safety
All service operations described in this
servicemanual are only to be carried out by well-
trained/qualified personnel and even then only after
this service manual has been read carefully and is
fully understood.
Personal safety
Observe all (inter)national and/or local safety
standards, measures and regulations during
reinstalling, repairing and connecting the compressor
(package).
Mechanical safety
If the compressor does not have to be removed from
its base, it is advisable to put warning labels on vital
parts of the compressor saying that the plant is out-
of-operation and must not be started up.
If the compressor has to be opened for service,the
refrigerant has to be pumped down and the electric
supply has to be cut off.
After having run the initial 100 operating hours,it is
essential (in both new and modified plants) to
replace the red running-in discharge oil filter element
with the permanent grey filter element. Also replace
the running-in suction gas filter element.
Check the direction of rotation is correct before re-
starting the compressor.
GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 3

PREFACE
General
1. All documentation can be downloaded via our
web site.
2. Grasso’s technical manuals includes “generic
paragraphs”; this means that it can occur that
not all data as described is relevant for the
current compressor series as mentioned in this
manual. (For instance, not all compressor series
are suitable for all mentioned refrigerants or not
all compressor series includes two-stage
compressors)
Directives
Equipment is based on Pressure Equipment
Directive (PED 97/23/EG) regulations and according
to Machine Directive (MD 2006/42/EG) regulations.
The applied standards are:
NEN-EN-IEC 60204, NEN-EN-ISO 12100, NEN-EN-
ISO 13857, NEN-EN 378

GENERAL INFO SIM

Warning!
Never change positions of parts when re-assembling the compressor. E.g. cylinder liners,
suction valves, discharge valves and relief valves have to be replaced always in the origional
position.
All bolts and nuts have to be mounted according to to the torques as given in table “Survey of
torques for bolts and nuts" as available in this manual. If you cannot find this information,
consult Grasso.
General
This compressor service manual is intended to be used in the field by qualified personnel of refrigeration
installers or contractors for proper(re)assembly, inspection,repair and part or total overhaul of Grasso single-
stage and two-stage piston compressors.
Installation and maintenance intructions

The manual should also and always be used together with the corresponding "Installation and Maintenance
Manual" (IMM) meant for the operator. The IMM is supplied with every compressor or compressor package.
Additional design details

Additional design details are available in the manual “Product Information“
How to read the pages of this manual
Fig.1
Hint!
When “[Tool set]” is mentioned in this manual, the tool as shown in the picture is part of the
Grasso V tool set, which can be supplied by Grasso.
Important tables, refer to Chapter 5, Page 68!
Hint!
Tables like “Wear limits and tolerances“ and “Torques for bolts and nuts“ can be found at
Chapter 5, Page 68


CYLINDER NUMBERING
Fig.2: Cylinder numbering Grasso reciprocating compressors
Legend
1, 2, 3, ... Cylinder numbers
T Top view of compressor
M Motor/Drive end of compressor
O Oil pump of compressor


GENERALINFO
Main setup data
Description Value Remark
Start frequency max. 6 starts per hour
Time interval between stopping and

min. 2 minutes
re-starting
Time interval between starting and

min. 10 minutes
re-starting
For continuous minimum part-load (i.e.

more than 30 minutes) consult Grasso.
Time interval between loading and
min. 3 minutes Adjust the steps between up and down
unloading
loading, in such a way that the system is
running stable.
Oil level 25-75% crankcase sight glass
> 10 oC and > Pcrankcase +

Min. oil temperature
15 K
Required oil viscosity;

Refer to oil selection table/
Max. oil temperature ≥ 10 cSt during operation at location of
applied type of oil
bearings
Control oil pressure suction pressure + 8 bar
After a mimimum of 15 minutes running

between 1.3 and 4.5 bar
Lubricating oil pressure difference time at an oil temperature of approx. 50
Setting approx. 2.0 bar oC (122 oF)
Max. discharge temperature 170 °C
Min. suction pressure 0.3 bar
NH3 - 7.0 bar

Max. intermediate pressure R22 - 7.0 bar
Max. suction pressure R134a - 6.2 bar
R404A - 6.0 bar
Pdischarge - Psuction ≤17.5 bar
>0 Kfor NH3,

Superheat
>15K for R507/R404A/R134a
Oil suction filter Blue coloured filter element

Main setup data
Description Value Remark
Hint!
Factory mounted; to be
Oil discharge - running in - filter Red coloured filter element replaced after max. 100
running hours by
permanent oil discharge
filter element
Hint!
Oil discharge - permanent - filter Grey filter element Supplied loose;

replacement for factory
mounted running in filter
Direction of rotation of compressor Counterclockwise when facing

drive shaft shaft end

TABLE OF CONTENTS
1 REPAIR AND OVERHAUL 13
1.1 INTRODUCTION 13
1.2 EVACUATION/DRYING THE REFRIGERATING SYSTEM 13
1.3 EVACUATION, LEAK TESTING AND START-UP OF THE COMPRESSOR/PACKAGE 13
1.3.1 EVACUATION OF REFRIGERANT BEFORE SERVICING 13
1.3.2 LEAK-TIGHTNESS AFTER SERVICING 14
1.3.3 EVACUATION AFTER SERVICING 14
1.3.4 START-UP AFTER SERVICING 14
1.4 GENERAL RECOMMENDATIONS 14
2 DISASSEMBLY 16
2.1 REMOVING FLYWHEEL 16
2.2 DISMANTLING SUCTION GAS FILTER 17
2.3 DISMANTLING THE PRESSURE RELIEF VALVE HOUSING 17
2.4 REMOVING DISCHARGE VALVE ASSEMBLY 18
2.5 REMOVING THE PISTON/CONNECTING ROD ASSEMBLY 18
2.6 REMOVING THE VALVE-LIFTING HOUSING AND CYLINDER LINER 20
2.7 DISMANTLING THE ROTARY SHAFT SEAL 21
2.8 REMOVING OIL SUCTION AND OIL DISCHARGE FILTERS 23
2.9 REMOVING OIL PUMP ASSEMBLY 24
2.10 THRUST BEARING 25
2.10.1 DISMANTLING STANDARD THRUST BEARING 25
2.10.2 HEAVY DUTY THRUST BEARING CONSTRUCTION 25
2.10.2.1 DISMANTLING HEAVY DUTY THRUST BEARING 26
2.11 REMOVING CRANKSHAFT, INTERMEDIATE BEARING AND MAIN BEARINGS 27
2.11.1 Introduction 27
2.11.2 Intermediate bearings in 4, 6, 9 and 12 cylinder compressors 27
2.11.3 2 and 3 cylinder compressors (i.e. without intermediate bearing) 27
2.11.4 4, 6, 9 and 12 cylinder compressors (with intermediate bearing) 28
2.11.5 Removing the crankshaft, METHOD A (without auxiliary tools) 28
2.11.6 Removing the crankshaft method B (with auxilary tools) 29
2.11.7 Internal oil connection line 29
2.11.8 Line coupling pieces 29
3 INSPECTION AND PREASSEMBLY 30
3.1 PRESSURE RELIEF VALVE ASSEMBLY 30
3.1.1 Back pressure dependent relief valve 30
3.1.2 Back pressure independent relief valve 30
3.2 LUBRICATING OIL PRESSURE REGULATOR 31
3.3 CONTROL OIL PRESSURE REGULATOR 32
3.4 VALVE-LIFTING CONTROL MECHANISM RC12 32
3.5 DISCHARGE VALVE ASSEMBLY 33
3.6 PISTON/CONNECTING ROD GRASSO 12 34
3.6.1 Pistons 2417011 (before mid 2015) 35
3.6.1.1 General 35
3.6.1.2 Connecting rod 35
3.6.1.3 Piston 36
3.6.1.4 Preassembling the piston/connecting rod 36
3.6.2 PISTON 38
3.7 CYLINDER LINER AND VALVE-LIFTING MECHANISM RC12 39
3.8 OIL PUMP AND OIL FILTERS 42
3.9 MAIN BEARINGS 46
3.10 ROTARY SHAFT SEAL 47
3.11 CRANKSHAFT 48
3.12 THRUST BEARINGS 49
3.12.1 STANDARD BRONZE THRUST BEARING, MARK 2 49
3.12.2 HEAVY DUTY THRUST BEARING 50
3.13 CRANKCASE 50
4 REASSEMBLING 51
4.1 CRANKSHAFT, MAIN BEARINGS AND INTERMEDIATE BEARING 51
4.1.1 Bearing cover driving side 51
4.1.2 Assembly procedure of 2 and 3 cylinder compressors 51

4.1.3 ASSEMBLY PROCEDURE 4, 6, 9 AND 12 CYLINDER COMPRESSORS 51

4.1.4 Pump side 52
4.1.5 Bearing cover oil pump side (with two lugs): 52
4.1.6 Standard thrust bearing 53
4.1.7 Heavy duty thrust bearing 53
4.1.8 Measuring the axial crankshaft play 54
4.1.9 Procedure for 4, 6, 9 and 12 cylinder compressors 55
4.1.10 Assembling counter weights 55
4.2 OIL PUMP 56
4.3 OIL SUCTION FILTER, OIL DISCHARGE FILTER, LUBRICATING OIL PRESSURE
REGULATOR AND CONTROL OIL PRESSURE REGULATOR 56
4.3.1 Oil discharge filter 56
4.3.2 Oil suction filter 57
4.3.3 Lubricating oil pressure regulator (without groove) 57
4.3.4 Control oil pressure regulator (with groove) 57
4.4 Replacement piston rings and cylinder liners 58
4.5 CYLINDER LINER 58
4.6 PISTON/CONNECTING ROD ASSEMBLY 59
4.7 DETERMINING THE PISTON CLEARANCE 60
4.8 VALVE-LIFTING CONTROL MECHANISM 61
4.9 SUCTION/DISCHARGE VALVE ASSEMBLY 62
4.10 ROTARY (SLIP RING) SHAFT SEAL 63
4.11 SUCTION GAS FILTER 65
4.12 PRESSURE RELIEF VALVE ASSEMBLY 65
4.13 Running-in oil filter has to be installed after an overhaul or big repair 65
4.14 OIL FILLING 65
4.15 MOUNTING FLYWHEEL 66
4.16 DISCHARGE VALVES, LEAKAGE TEST PROCEDURE 67
5 MISCELLANEOUS 68
5.1 SURVEY OF TORQUES FOR BOLTS AND NUTS 68
5.2 WEAR LIMITS AND TOLERANCES 70
5.3 REQUIRED SERVICE TOOLS AND MATERIALS 72
5.4 GRASSO SPECIAL TOOLS AND AIDS 73
5.5 FITTING INSTRUCTIONS FOR PIPE COUPLINGS AND DOUBLE LOCKING RING 73
5.6 MASS OF SEPARATE COMPONENTS AND COMPRESSORS 73
5.7 RELIEF VALVE POSITIONS 74
5.8 MOUNTING O-RINGS 78

1 REPAIR AND OVERHAUL

For evacuation of compressor only, refer to
Section 1.3, Page 13
1.1 INTRODUCTION
Procedure to evacuate and to dry a system:
Compressor and plant
i. STATUS: System is filled with nitrogen and no
All activities described can be carried out without oil has been added (oil prevents any trapped
taking the compressor off its base and without moisture from boiling off).
detaching it from the plant. In case of complete
overhaul, it may, however, be useful to carry this out ii. Verify that all valves in that part of the system
detached from the plant in a separate working area, to be evacuated are opened (refer also to the
whether or not in a workshop equipped for this plant manual).
purpose. iii. Connect vacuum pump to the evacuation/
Accessories purging valve(s) of the compressor (for location
of these valves refer to the "Product
This chapter only deals with the disassembly and Information" or to a connection as mentioned in
assembly of a so-called "bare compressor" in the plant manual and evacuate the system to
standard design. This implies that, depending on the approx. 6 mBar.
dismantling degree, it may be necessary to first
completely or partially remove certain accessories. iv. Break vacuum by charging dry nitrogen into the
system.
It is recommended to distinctly mark the dismounted
accessories or parts of them (for instance oil control v. Repeat step iii, "Connect vacuum pump ...".
lines and pressure gauge or safety switch lines, vi. Wait approx. 24 hours.
transducers, pressure and temperature sensors, V-
belt pulleys and torsionally-stiff coupling) in order to vii. If pressure has increased (system still contains
avoid mistakes at reassembling. moisture), repeat steps iv, and vi. Otherwise,
continue with the "Initial oil charge" procedure.
Tools
For proper performance of the operations, at least
the standard service tools and materials should be 1.3 EVACUATION, LEAK TESTING
available. AND START-UP OF THE
Besides, for certain operations additional special COMPRESSOR/PACKAGE
GRASSO tools are required, which can be obtained
To evacuate the refrigeration system refer to
as a complete standard service set.
Section 1.2, Page 13,
Service Sets Always use a vacuum pump or pump-down unit to
Worn out parts are to be replaced by new parts evacuate the refrigerant from the compressor.
which are available in sets with a brief service
manual.
1.3.1 EVACUATION OF
General REFRIGERANT BEFORE
Although all the assembly and disassembly SERVICING
procedures shown relate to the two-stage
compressor, they are basically applicable universally Procedure to evacuate the compressor:
to all compressors. If not, it is explicitly stated in the 1. Switch off main control panel
text.
2. Remove main fuses
3. Close shut-off valves
1.2 EVACUATION/DRYING THE
REFRIGERATING SYSTEM

4. Remove the refrigerant by means of a vacuum 8. Re-install the main fuses.

pump or pump-down unit, via the evacuation/
9. Start up the compressor.
purging valve(s) as prescribed by local safety
regulations. For the location of these valves refer 10. Check running condition.
to the "Product Information".
Note:
5. Drain the oil from the compressor and oil The job isn't finished until the paper work is done!
separator, oil return /oil rectifier system if Complete the service report, e.g. Grasso report
present. 00.89.062.
1.3.2 LEAK-TIGHTNESS AFTER 1.4 GENERAL RECOMMENDATIONS

SERVICING
The necessary safety precautions should be taken Caution!
before carrying out the leak-tightness test. To check Always use new gaskets, O-rings and
leak-tightness use dry nitrogen at a positive pressure locking rings when reassembling after
which is less than the admissible operating pressure inspection or repair.
of the low pressure stage. Use a torque wrench to tighten the
threaded connections. (Survey of
torques for bolts and nuts)
1.3.3 EVACUATION AFTER
SERVICING 1. Do not disassemble more compressor parts than
is necessary for the purpose (inspection, repair,
After the pressure test has been completed, the overhaul).
compressor (package) must be evacuated and
undergo a vacuum test. Evacuation is used to 2. Use clean and well-conditioned tools.
remove air and moisture from the compressor 3. Make sure that there is a clean and neatly
(package) arranged working area well-equipped to provide
temporary and adequately protected storage of
dismantled components. Preferably use a table
1.3.4 START-UP AFTER SERVICING or working bench with a clean, moisture-free and
non-scratching surface.
1. STATUS: Compressor (package) is dried and
still evacuated. 4. Immediately clean every dismantled part, check
it for wear or damage and oil the machined
2. Charge the oil separator, if present, with oil. surfaces of bright parts. The oiling is particularly
See the appropriate Product Information for the important when the parts are not to be
correct quantity. reassembled until after some time. Otherwise
3. Charge the compressor crankcase with oil via they will certainly become rusty.
the oil charge valve until the minimum level is 5. The dismantled parts of every cylinder (cylinder
seen at the sight glass at the level as indicated in liner, piston, connecting rod, valves) or of other
IMM. main components should be kept together
It is mandatory to pre-lubricate the oil circuit by separately and marked if necessary. Thus they
adding the final quantity of oil via the charge can later be replaced in their original place in the
valve mounted onto the oil pump by means of a compressor.
separate oil filling pump. The required oil level is 6. All major parts that are not beyond repair have to
indicated in the IMM. be checked before reassembly for wear by
4. Re-install all accessories such as coupling, V- measuring them and comparing the outcome
belt guard etc. with the wear limits and tolerances given in
documentation.
5. Open the shut-off valves.
6. Check the start-stop procedure.
7. Check all safeties and controls.

7. Always replace damaged or worn compressor

parts that are beyond repair by new GRASSO
standard spare parts. These parts can always be
fitted into the compressor without previous
inspection or readjustments (if applicable, e.g.
valves, connecting rods, etc.).
8. When fitting any moving parts, it is
recommended to oil all running surfaces.

2 DISASSEMBLY
2.1 REMOVING FLYWHEEL

For many service and repair operations the flywheel
or the V-belt pulley has to be removed.
Fig.5
5. Remove the four M12 hexagon head bolts.

6. Fix a sling on the top of the wheel. Pull the sling
in such a way that the wheel can still move freely
Fig.3
on the shaft.
1. Alternately unscrew the four M12-bolts five

rotations (screwing anticlockwise).
Fig.6
7. Remove the locking disc.

Fig.4
2. Remove the locking plate.

3. Unscrew the centre M24-bolt five rotations
(screwing anticlockwise).
4. Loosen the wheel by alternately tightening the
four M12-bolts clockwise. Keep screwing until
the wheel is entirely loose.
Fig.7

1. Now slide the wheel or V-belt pulley hanging in

the sling off the compressor shaft.
2.2 DISMANTLING SUCTION GAS

FILTER
Fig.9: Back pressure dependent relief valve
The LP pressure relief valve housing is mounted

against the cylinder block.
1. Unscrew four of the six M12 bolts out of the
cylinder block and remove the bolts.
Fig.8
2. Unscrew the two remaining M12 bolts and
Lege remove the housing.
nd
Warning!
1 Cover If there is any doubt about the proper
performance of a pressure relief valve,
2 Spring then the relief valve should be
renewed immediately. When a
3 Filter pressure relief valve works improperly,
discharge gas starts circulating
through the cylinder head, which
makes this cylinder head feel much
1. Remove the bolts from the left cover of the
warmer compared to other cylinder
suction gas filter housing.
heads.
2. Remove the cover with the pression spring and Never test the relief valve by closing
filter mounted to it from the housing. the discharge valve of a running
3. After the circlip ring has been removed from the compressor. This will damage the seat
centring pin, the filter can be easily removed. of the relief valve.
4. Remove the O-ring from suction gas filter and

replace a suction filter if it is dirty.
5. NOT FOR 21, 42, 63 and 84 compressors1:
Remove the cover on the right handed side of
the suction gas filter housing in the same way
and clean the inside of the housing.
2.3 DISMANTLING THE PRESSURE

RELIEF VALVE HOUSING
Fig.10: Back pressure independent relief valve
1 Right side cover does not exist for 21, 42, 63 and 84
compressors

Hint! 4. Release the buffer spring tension by alternately

unscrewing the two nuts on the longer studs.
For regular service it is not necessary
to remove the pressure relief valve
from its housing. However, if it has
worked once, it can be dismantled/
serviced as described in this manual.
Fig.13: Discharge valve assy
Legen
d
1 Buffer spring
Fig.11: Blind flanges
2 Pressure spring cup

Hint!
In some compressors blind flanges 3 Discharge valve assembly
have been fitted at the connecting
opening. There is no need to remove 4 Sinusoidal springs
these blind flanges during normal
servicing or repair. 5 Suction valve ring
5. Remove the cylinder head cover, the buffer

2.4 REMOVING DISCHARGE VALVE spring, the pressure spring cup, the discharge
ASSEMBLY valve assembly with the two suction valve
sinusoidal springs and the suction valve ring.
2.5 REMOVING THE PISTON/

CONNECTING ROD ASSEMBLY
Fig.12
1. Remove dirt and paint particles from the cylinder

head studs using a steel brush.
2. Oil all studs.
Fig.14
3. Remove all M16 bolts from the short studs.

1. Place an oil drip tray under the service cover that

is to be removed to collect the residual oil in the
inclined crankcase openings.
2. Remove the service cover with O-ring opposite
the cylinder under repair.
3. In the case of vertical cylinders, remove the
opposing service covers.
Fig.16
5. Unscrew the two M16 nuts from the connecting

rod bolts and remove the (double) locking rings.
Fig.15
4. Rotate the crankshaft in such a way that the big

end of the connecting rod becomes easily
accessible.
Fig.17
6. Tap up both connecting rod bolts a small amount

of force so that the connecting rod cap can be
removed easily.
7. Pull both connecting rod bolts back to their
original places in the connecting rod.

8. Move the piston that is to be removed to top

position by rotating the crankshaft by hand.
Fig.19
Fig.18 1. Disconnect the oil line on the valve-lifting

housing.
9. Insert the T-handle (from auxiliary tool kit) into 2. Mark the position of (each) valve-lifting housing
the threaded hole at the top of the piston and on the corresponding mounting flange.
carefully pull the piston and the connecting rod
3. Remove the entire housing, including the control
out of the cylinder liner, making sure that the big
piston in it, by unscrewing the M10 bolts off the
end of the connecting rod does not damage the
cylinder jacket.
cylinder liner.
10. Hint!
Hint!
REMARK: The valve-lifting housing
The connecting rod cap is marked
can remain mounted to each cylinder
and belongs to a specific
wall if: - the control mechanism does
connecting rod. There is only one
not need to be inspected; - the
way to refit it onto the connecting
cylinder liner does not have to be
rod. Therefore conrod numbers
removed.
should always be situated on one
side. Keep the corresponding
connecting rod parts together!
11. Inspect the cylinder liner bore
Hint!
Measure the bore in three places of the
empty and cleaned cylinder liner,
being at the top, in the middle and at
the bottom, and replace if the bore is
larger than is given, or if the honing
marks have (partly) disappeared.
Fig.20
2.6 REMOVING THE VALVE-LIFTING

4. Remove the pressure pin from the plug and
HOUSING AND CYLINDER LINER
clean both the pressure pin and the bore in the
end plug with respect to the measuring
inspection described hereafter.
5. Inspecting the (hexagon) plug and pressure pin:

6. 6.a. Check the bore or the still mounted plug

and replace it with a new pressure pin if
the bore is over 14.07 mm.
6.b. Check the pressure pin for irreparable
damage.For dismantling and/or inspection
of the pressure pin, refer Section 4.8,
Page 61.
Fig.23
9.d. Remove the gasket of the cylinder liner

collar, determine the original thickness of
the gasket (1.0, 1.25 or 1.50 mm) and write
down this value on the corresponding
cylinder wall.
Fig.21 9.e. Check the still mounted semi circular lever

and supporting ring with dowel pin (= ø6
7. Place the longer green bar2 over two studs of the mm) for irreparable damage.
cylinder head.
8. Insert the threaded rod with nut and washer into 2.7 DISMANTLING THE ROTARY
this bar. SHAFT SEAL
9. Place the short green bar centrally across the
bottom of the cylinder liner.
9.a. Screw the threaded rod into this short bar
until the assembly is fully closed.
9.b. Now tighten the nut until the cylinder liner
is loose.
Fig.24
1. Dismantle and remove the leakage drain from

the bottom of the shaft seal housing.
Fig.22
9.c. Remove the auxiliary tools and take out the

cylinder liner by hand.
2 All these parts are included in the auxiliary tool kit ETA.

5. Take the counter slip ring from the shaft seal

housing, remove the O-rings from the counter
slip ring and from the rear side of the housing.
Fig.25
2. Remove the drive key from the crankshaft driving

end. Fig.28
6. Unscrew the three locking screws at the

circumference of the slip ring shaft seal using the
M4 allen key from the auxiliary tool kit .
Fig.26
3. Place the oil drip tray under the shaft seal

housing and remove the M12 bolts from the shaft
seal housing. Fig.29
7. Place two similar screwdrivers behind the slip

ring and carefully push the grips into the
direction of the crankcase until the slip ring is
loose.
7.a. Do not scratch the crankshaft!
Warning!
Avoid touching the (black) carbon ring
(if necessary wear gloves or rub your
hands with oil) and the lapped counter
surface of the ring.
Fig.27
8.
4. Slide the shaft seal housing over the shaft
journal out of the bearing cover.

Fig.30
9. Slide the slip ring from the shaft .
2.8 REMOVING OIL SUCTION AND

OIL DISCHARGE FILTERS
Hint!
Pictures of oil pump are without the
normally fitted oil charge valve.
Hint!
It is also possible to remove the oil
pump and the filters mounted to it as a
whole. If the filter elements only have
to be inspected or replaced, it suffices
to unscrew the grooved filter nut and
the filter housing that has to be Fig.31: Special tool for removing oil filters
supported by hand, after an oil drip
tray has been placed under it.
Hint!
Use the special tool key for removing
oil filters.
Fig.32: Oil pump and filter

1.a. Unscrew the M12 nuts from the studs and

slide the pump as a whole over the studs.
Hint!
If required, the oil pump can also be
removed with both oil filters still
mounted to it.
Fig.33
Fig.35
2. Remove the carrier disc which was left behind

after removal of the oil pump.
Fig.34
1. In order to remove the entire oil suction filter

(left) and/or the oil discharge filter (right), only
the two M10 mounting bolts of each filter have to
be removed.
2. Mark the filter housing to prevent interchange!
3. Hint!
As both filter housings are Fig.36
identical and can possibly be
interchanged, every filter element 1. Remove the now accessible four M10 socket
is marked with a colour: - Red for bolts connecting the hold down disc with the
the running-in oil discharge filter crankshaft.
which must be replaced within the
first 100 hours with a grey 2. 2.a. Carefully remove the hold down disc with
coloured oil discharge filter. The the fitted dowel pin from the crankshaft.
oil suction filter is coloured blue. Warning!
On the crankshaft side this hold down
disc is provided with a lapped surface.
2.9 REMOVING OIL PUMP Damage to this surface as a result of
ASSEMBLY rough use are very hard to repair and
reuse of such a hold down disc can
1. Put an oil drip tray under the pump to collect the damage the compressor within a short
residual oil. time!

2.10 THRUST BEARING 2.10.1 DISMANTLING STANDARD

THRUST BEARING
Two types of thrust bearings have to be considered
1. Standard
1.a Bronze, mark 2, (latest version), refer
Figure 37, Page 25
1.b Aluminium (old version), refer Figure 38,
Page 25
2. Heavy duty
Fig.39
1. The released thrust bearing can now be carefully

removed with an allen key (from the shaft seal kit
or auxiliary tool set).
Hint!
As the adhesive power behind the
Fig.37: Standard bronze thrust bearing, “mark 2” thrust bearing has to be overcome, the
ring can suddenly slip off.
2.10.2 HEAVY DUTY THRUST

BEARING CONSTRUCTION
In addition to the standard design there is an
alternative "heavy duty" roller thrust bearing
available for certain applications and consists of a
twin type roller assembly. One main bearing for the
Fig.38: Old version of standard thrust bearing, aluminium. outward pull of the crankshaft and a second one for
inward push of the crankshaft during vacuum
operation. The total assembly is pre-loaded by
means of springs to ensure proper running
conditions are achieved.
Hint!
Compressors fitted with roller thrust
bearings can be easily recognised by
an external oil overflow line running
from the oil pump to one of the
crankcase covers and a marking on
the top of the oil pump. (Compressors
fitted with the standard thrust bearing
arrangement have an internal overflow
back to the crankcase and no marking)

2.10.2.1 DISMANTLING HEAVY DUTY

Warning!
THRUST BEARING
All running surfaces of the washers in
Remove external oil line, oil pump and carrier contact with the cylindrical roller
disk thrust bearing and the needle thrust
bearing are hardened and smooth
machined. Damages to these surfaces
as a result of rough use are very hard
to repair and reuse of such rings can
damage the compressor within a short
time
1. Remove the 7 mm. thick housing washer (1)

from the hold down disc (4).
2. Remove the needle thrust bearing (2) from the
hold down disc (4).
3. Remove the now accessible four M10 socket
bolts (3) and the hold down disc (4) which is
connected to the shaft washer (5).
4. Remove the shaft washer (5) from the
crankshaft.
5. Remove the cylindrical roller thrust bearing (6)
Fig.40: External oil line
from the crankshaft.
1. Remove the external oil line (1) which is 6. The released 1 mm. thick thrust washer (7) can
connected from the top of the oil pump to the be carefully removed with a wire hook as shown
service cover. Figure 42, Page 26.
2. .Remove the oil pump. Unscrew the M12 nuts,

take off the washers and slide the oil pump of the
M12 studs
2.a. Pay attention not to lose the springs or the
spring retainer.
3. Remove the carrier disc.
Remove heavy duty thrust bearing
Fig.42: Remove thrust washer with hook (1)
6.a. The bearing cover has been equipped with

Fig.41: Heavy duty thrust bearing three round shaped chambers to create
space for a wire hook to grip behind the
thrust washer for removal.

Warning!
As the adhesive power behind the 1
mm. thick thrust washer (7) has to be
overcome, the ring can suddenly slip
off.
7. Remove the spring retainer (8) from the oil pump

housing.
8. Remove the springs (9) from the spring
retainer(8)
Fig.44
2.11 REMOVING CRANKSHAFT,
INTERMEDIATE BEARING AND
1. Mark both bearing block parts of each
MAIN BEARINGS intermediate bearing so that they can later be
refitted in the same position. For easy reference
the crankshaft has been left out!
2.11.1 Introduction 2. 2.a. Remove both M20 bolts with
corresponding toothed spring washers
1. Before starting, the following components must from the intermediate bearing support(s) in
have been removed: the crankcase.
1.a. All discharge valves It is not necessary to remove the counter weights
from the crankshaft, but on account of the
1.b. All pistons and connecting rods
crankshaft weight, the counter weights may
1.c. Shaft seal and key preferably be dismantled.
1.d. Oil pump
1.e. Thrust bearing
Hint!
In case of direct drive, preferably
remove the crankshaft via the pump
side.
Fig.45
3. Write down the markings of the counterweights

before they are taken off the crankshaft for
faultless replacement later on.
4. 4.a. Unscrew both M16 bolts from each
counterweight.
Fig.43 4.b. Remove the counterweights with the

(double) locking rings.
2.11.2 Intermediate bearings in 4, 6, 9 2.11.3 2 and 3 cylinder compressors

and 12 cylinder compressors (i.e. without intermediate bearing)

1. Remove the swivel on top of the bearing cover 3. Remove the bearing cover (and the O-ring) and
on the pump side. put it aside separately.
2. 2.a. Unscrew all M16 nuts from the studs of the Hint!
bearing cover on the pump side.
As the 4 and 6 cylinder compressor
2.b. Screw two M10 (jacking) bolts into the has only one intermediate bearing, the
threaded holes on both sides of the crankshaft has to be supported.
bearing cover.
2.c. Tighten these two bolts evenly and
alternately until the bearing cover is loose.
Fig.47
4. Unscrew all M16 nuts from the studs of the

Fig.46 bearing cover on the driving side.
5. 5.a. Tighten the two jacking bolts further until
3. 3.a. Remove the bearing cover with the
the bearing cover is loose.
corresponding O-ring on the pump side.
Now the crankshaft of the 2 and 3 cylinder 5.b. Remove the bearing cover (and the O-ring)
compressor only rests in the bearing cover and put it aside separately.
on the driving side.
3.b. Assisted by a second person, now carefully
remove the crankshaft from the crankcase
2.11.5 Removing the crankshaft,
through the opening on the oil pump side. METHOD A (without auxiliary
tools)
3.c. Put the crankshaft down on a clean place.
If the bearing is only to be inspected, there is no
need to remove the parts mentioned.
2.11.4 4, 6, 9 and 12 cylinder

compressors (with intermediate
bearing)
1. Remove the swivel on top of the bearing cover

on the pump side.
2. 2.a. Unscrew all M16 nuts from the studs of the
bearing cover on the pump side. Fig.48
2.b. Screw two M10 (jacking) bolts into the

1. Remove the crankshaft of the 4, 6, 9, and 12
threaded holes on both sides of the
cylinder compressor in steps.
bearing cover.
2.c. Tighten these two bolts evenly and
alternately until the bearing cover is loose.

2. 2.a. Make use of the intermediate bearings

and/or crank webs and the still mounted
counter weights, for use as supports on the
edges of the crankcase openings.
2.b. With the 4, 6, 9 and 12 cylinder
compressor, unscrew the four M16
intermediate bearing bolts.
2.c. Remove both bearing block halves from
the crankshaft and prepare them for
inspection by reassembling them to each
other leaving out the crankshaft.
3. The crankshaft can be removed more easy by Fig.50
making use of a simple tool. This method B (with
auxiliary tool) is described below. 1. Uncouple and remove the internal oil connecting
line and remove the oil line.
2.11.6 Removing the crankshaft method

B (with auxilary tools) 2.11.8 Line coupling pieces
Fig.49
Fig.51
1. By sliding the long tool (not available from

Grasso) over the shaft end on the pump side and 1. Remove all line coupling pieces from both sides
the short tool over the shaft end on the driving of the crankcase.
side, the crankshaft can now be easily removed
from the crankcase with assistance from a
second person.
2. 2.a. With the 4, 6, 9 and 12 cylinder
compressor unscrew the M16 intermediate
bearing bolts.
2.b. Take both bearing block halves from the
crankshaft and prepare them for inspection
by reassembling them to each other
leaving out the crankshaft.
2.11.7 Internal oil connection line

3 INSPECTION AND PREASSEMBLY

3.1.2 Back pressure independent relief
Warning!
valve
All bolts and nuts have to be mounted
according to to the torques as given in
table “Survey of torques for bolts and
nuts" as available in this manual. If
you cannot find this information,
consult Grasso.
3.1 PRESSURE RELIEF VALVE

ASSEMBLY
General
Fig.53: Back pressure independent
A defect or malfunctioning pressure relief valve can
and may not be repaired. In these cases a new relief
valve has to be ordered (safety regulation). This back pressure dependent pressure relief valve
consists of two major components, the pressure
Two different types of relief valves can be applied: relief valve housing (1) and the pressure assembly
1. Back pressure dependent (2). With this pressure relief valve it is permitted to
replace only the pressure assembly (2) without the
2. Back pressure independent
valve housing (1).
1. The cause of a malfunctioning pressure relief
3.1.1 Back pressure dependent relief valve is usually a minor damage in the teflon
valve seal of the pressure assembly (2).
2. Check the valve seat in the pressure relief valve
housing (1).
3. In order to inspect this, only the four M12 bolts
(3) have to be unscrewed from the pressure
relief valve housing to remove the pressure
assembly (2).
4. If damage or wear of the teflon ring of the
pressure assembly (2) is detected, check
whether this can be remedied by polishing.
5. Slight wear can be remedied with polishing
paper.
6. Reassemble all parts into a whole after
inspection/repair.
Fig.52: Back pressure dependent
Hint!
This type of relief valve can be
supplied with different factory
settings. Never change these relief
valve(s) from compressor and/or
position.

3.2 LUBRICATING OIL PRESSURE

REGULATOR
Fig.55
Legend
1 Cap
Fig.54: Oil pressure regulators
2 Housing
1. The lubricating oil pressure regulator (not

3 Pressure spring
equipped with a groove in the hexagon nut) (see
Figure 54, Page 31) is fitted in the left-hand side 4 Ball
of the pump and can be taken out with the help
of a ring spanner or socket spanner 41, provided 5 Circlip ring
that the oil suction filter has been removed.
6 Set bolt
7 O-ring
8 Alu-ring
2. Renew O-ring (7) and Alu-ring(8)

All parts forming the regulator do not need wear
inspection, but it is recommended to clean all
(disassembled) regulator parts, to oil them with
compressor oil and to reassemble.
Hint!
The pressure can be adjusted with a
screwdriver only during operation.

3.3 CONTROL OIL PRESSURE

REGULATOR
Fig.58
1. Remove the control piston (3) from the housing

(1) with the T-handle (part of the auxiliary tool
Fig.56: Oil pressure regulators kit).
1.a. Remove the O-ring (4) and clean the
piston.
1.b. Clean the control piston bore in the valve-
lifting housing and check this for wear or
slight damage (which may be remedied
with polishing paper) and replace the
housing if the bore is over 51.075 mm.
1.c. Renew the O-ring (2), fit the lubricated
piston with a new O-ring (4) into the
housing and put it apart to be reassembled
later.
Fig.57: Control oil pressure regulator 1. If the pressure pin cannot easily move in and out
of the (firmly tightened) plug (on the side of every
cylinder head), due to slight wear or damage of
1. The control pressure regulator (equipped with a
the dowel pin and in the bore of the plug this
groove in the hexagon nut, see lower regulator in
may be remedied with polishing paper.
Figure 56, Page 32) fitted in the right-hand side
of the pump can be taken out with a ring spanner 1.a. In the case of irreparable damage or wear,
or socket spanner 41, provided that the oil both the plug and the dowel pin have to be
discharge filter has been removed. replaced.
2. Disassemble, inspect and reassemble as
described in relation to the lubrication oil
pressure regulator.
3.4 VALVE-LIFTING CONTROL

MECHANISM RC12

3.5 DISCHARGE VALVE ASSEMBLY

General
Fig.59: 8
Fig.61: 10
1. Insert an 8 mm allen key into the bottom of the

1. Replace the discharge valve sinusoidal springs
discharge valve assembly.
when they are damaged/discoloured and when
1.a. Clamp the allen key in a vice and remove the untensioned height "h" is less than:
the M16 nut (6) from the central bolt (2), - 2.2 mm for the sinusoidal springs with the
the double locking ring (8), the discharge smallest diameter,
valve stroke limitor (7), the sets of valve
- 3.5 mm for the sinusoidal springs with the
rings (3a, 4a and 5a) and sinusoidal
medium diameter,
springs (3b, 4b and 5b)
- 5.5 mm for the sinusoidal springs with the
1.b. Thoroughly clean all valve parts and the largest diameter.
valve plate (1).
1.a. Also replace the valve seat if due to wear
the total scoring of the seat is over 0.2 mm.
Fig.60: Stroke limitor
2. Inspect the discharge valve stroke limitor and the

valve ring guide cams on the bottom side of the
stroke limitor for wear.
In case of wear (shifting of valve rings and valve
springs) or damage due to another cause, the
Fig.62: Valve plate
discharge valve stroke limitor has to be renewed.
2. Check the discharge valve seat for damage,

wear or scoring. If during this inspection the
valve plate appears to have made contact with
the piston, the connecting rod bearings have to
be checked as well; the clearance should then
be determined.

Preassembling the discharge valves Suction valve
Fig.63: 12
Fig.65: 10
1. Place the 3 dischare valve rings in their

respective locations on the valve seat then cover 1. Replace the suction valve sinusoidal springs
each with the corresponding pair of sinusoidal when they are damaged or discoloured and
springs (with convex side facing away from the when the untensioned height "h" is less than 9.6
valve plate). mm.
Carefully position the discharge stroke limitor 1.a. Also replace the valve seat if due to wear
over the valve plate without dislodging the ring the total scoring of the valve seat is over
and spriings. 0.2 mm.
1.a. Adjust the clamped valve rings and valve 1.b. Also check the suction valve rings and
springs with a screwdriver until all cams of replace them if the thickness "t" is less
the stroke limitor touch the valve seat. than 0.8mm in various places.
1.b. Fit the (M16) central bolt with a nut and a
new double locking ring.
3.6 PISTON/CONNECTING ROD
1.c. Tighten this bolt/nut joint to the torque as GRASSO 12
given in Section 5.1, Page 68.
Since spring 2015, a new type of piston configuration
has been introduced as replacement for the original
configuration item no. 2417011.
This new piston assy DN160 with item no. 2417160,
shows deviating features in comparison with the first
type of piston:
1. 1. Piston body geometry.
2. 2. Piston ring arrangement and types.
3. 3. Gudgeon pin dimensions and fixation method
in the piston body: bolt connection for 2417011,
Fig.64 locked by circlip rings for 2417160.
Hint!
2. Place the discharge valve with the nut in the
vice. The parts, of which the both types of
piston units are assembled of, are not
2.a. Fill the openings with, for instance, mutually exchangeable!
kerosene or paraffin. After 2-3 minutes no
leakage should be visible. Even when old and new piston assemblies can be
used in one compressor, due to the same weight and
main dimension, we recommend keeping one type of

configuration in the machine. In case not all pistons

or piston assemblies can be replaced in one
compressor during a repair or maintenance, we
strongly recommend registering the assy part no.
(old or new) per cylinder to avoid ordering non
suitable piston ring sets or gudgeon pins in future.
Until further notice, the old sub parts/part no’s remain
available.
3.6.1 Pistons 2417011 (before mid

2015)
3.6.1.1 General
Fig.67
2. Heat the piston to approximately 80 °C

3. NEVER HEAT WITH OPEN FLAME! Pouring a
little spirit into the piston and lighting it works just
as well.
3.a. Push the gudgeon pin out of the piston.
3.b. Check the (cooled) gudgeon pin for wear
and measure the outer diameter using an
outside micrometer and replace the pin if
the diameter is smaller as the value given.
3.6.1.2 Connecting rod
Fig.66
1. Place the assembly upside down on the working

bench and straighten the locking plate under the
locking bolt.
1.a. Unscrew the M12 locking bolt and remove
the locking plate.
Fig.68
1. Assemble the bearing shells and the connecting

rod cap into a whole.
1.a. Tighten the nuts on the connecting rod
bolts to the torque given.

1.b. Measure the bore of the clamped bearing

with an inside micrometer and replace if it
is larger as the value given.
1.c. Check the bronze bearing bush (for the LP
cylinders) in the small end of the
connecting rod for wear or damage.
1.d. With an inside micrometer measure the
bore of the still fitted bronze bearing bush
and replace if it is larger as the value
given.
Fig.70
1.e. Insert a new bearing bush by lowering the
non-heated bearing bush into the small
end of the connecting rod which has been 2. Roll each piston ring and oil scraper ring in the
heated to approx 80 °C. corresponding groove around the piston to trace
parts that have become wedged. This can be
1.f. Check the condition of the double-row remedied, for example, by using a smooth file.
needle bearing (for the HP cylinders) and
replace if necessary. 2.a. Also check the rest of the piston for wear
or damage.
1.g. Insert the needle bearing as described for
the bearing bush.
3.6.1.3 Piston
Fig.69
1. Remove the three piston rings and the two oil Fig.71
scraper ring using the appropriate piston ring
pliers. 3. Check the gap in each piston ring by placing it in
an unworn part of the cylinder liner. These
1.a. Check the piston grooves for burrs, notch
unworn parts can be found at about 10 mm from
effects and cracked or broken grooved
the bottom of the cylinder liner. The max. gap
edges.
may not exceed 2.1 mm.
3.6.1.4 Preassembling the piston/

connecting rod

2.b. Insert the bronze bearing bush (for LP

cylinders) or respectively the needle
bearing, distance ring and needle bearing
(for HP cylinders) into the small end of the
connecting rod.
2.c. Check whether the needle bearings project
equally on both connecting rod ends.
2.d. Let the connecting rod cool off in ambient
air.
2.e. Fit the bearing shells in both connecting
rod parts. Due to the raised fixing cams
only one building-in position is possible.
Fig.72: Piston
Legend
T Top
CHR Chromium-plated
1. If the piston rings and oil scraper ring are no

longer on the piston, fit them in the sequence as
shown. Never mix old and new rings together.
When placing the rings, pay attention to the word Fig.74
"TOP" on each ring.
3. Heat the piston to approximately 80 °C,
DEFINITELY NOT IN OPEN FIRE!
Pouring a little spirit into the piston and lighting it
works just as well.
4. 4.a. Degrease the gudgeon pin and oil it.
4.b. Check that the gudgeon pin fits properly
into the connecting rod.
4.c. Hint!
With the HP connecting rod it
may be necessary to heat the
small end of the connecting
rod as well. Place the
connecting rod into the
piston and slide the oiled
Fig.73 gudgeon pin through the
piston into the connecting
2. Clean the connecting rod and blow out the oil rod.
passageway in the connecting rod.
2.a. When replacing the bearing bushes or
needle bearings, heat the small end of the
connecting rod to approximately 80 °C.

Warning!
The hole in the gudgeon pin has to
coincide with the locking bolt hole in
the piston.
Fig.77: Replace the NEW piston rings; Roll each piston ring and
oil scraper ring in the corresponding groove around the
piston to trace parts that have become wedged.
2. Check the rest of the piston for wear or damage
Fig.75
5. For locking, position the flat face of the head of

the hexagon bolt parallel with the piston wall.
Lock the locking bolt with the locking plate: tap
one face against the bolt head and the other
faces against the piston cam. Fig.78: Check the gap in each piston ring by placing it in an
unworn part of the cylinder liner. These unworn parts
can be found at about 10 mm from the bottom of the
cylinder liner. The maximum gap as given ()
3.6.2 PISTON
Warning!
Never use new piston rings in
combination with a worn out cylinder
liner.
Hint!
Never mix old and new rings together.
Fig.76: Remove the piston rings and the oil scraper ring (tool
not in tool set)
1. Check the piston grooves for burrs, notch effects

and cracked or broken edges

Fig.79: Piston Grasso 12 Series; T=Top, CHR=Chromium-

plated Fig.82: When placing the rings, pay attention to the word
“CTOPZ” and “C” on the oil scraper ring
3.7 CYLINDER LINER AND VALVE-

LIFTING MECHANISM RC12
General
Fig.80: Fit the piston rings and oil scraper in the orientation as
shown. When placing the 2 rings, pay attention to the
word “TOP” and “G1” on the oil scraper ring
Old situation before mid 2015; 2471012

Fig.83
1. Unscrew the locking nuts (3) from both M6 tie

bolts (1). Remove both tie bolts, the nuts (3) and
the springs (2).
Fig.81: Fit the piston rings and oil scraper in the orientation as
shown

Fig.84 Fig.86
2. Place the cylinder liner upside down on the 6. Clean all parts.
working bench.
2.a. Remove the split pin (2) from the dowel pin
(1) and slide the dowel pin out of the valve-
lifting lever (3).
2.b. Remove the lever.
Fig.87
7. Check the suction valve ring seat in the cylinder

liner collar for damage or locally worn away
honing tracks.
It is not necessary to check the cylinder liner
Fig.85
diameter if the honing tracks in the cylinder liner
bore are still complete. Irregularities can be
3. Carefully tap with a hammer against the carefully eliminated with abbrasive paper.
supporting ring (1), turning it clockwise, until the
wire spring (2) is loosened from the supporting 7.a. Check the outer surface of the cylinder
ring. liner for damage and eliminate slight
damages with abbrasive paper.
4. 4.a. Remove the wire spring.
7.b. Check the pressure ring on the inside.
5. Slide the supporting ring (1) and the pressure After truing up the inner and/or outer
ring (3) off the cylinder liner. surfaces, check whether the pressure ring
moves smoothly around the cylinder liner.

Preassembling the valve-lifting mechanism
Fig.90
Fig.88
2. Insert the wire spring, which should be 10 mm
longer than the groove circumference of the
1. Before starting, oil all parts with compressor cylinder liner, between the cams of the
lubricating oil. Place the cylinder liner with the supporting ring into the groove; this groove is
collar on the working bench. Slide the pressure accessible through the insert hole in the left cam.
ring over the cylinder liner. Slide the wire spring into the groove as far as
possible. With a soft hammer tap the supporting
ring around the cylinder liner (constantly turning
counter-clockwise), which makes the wire spring
slide further into the groove.
Fig.89
1.a. Slide the pressure ring with the hinging

holes facing upward over the cylinder liner
as far as the (wire spring) groove indicated Fig.91
with arrow "P".
3. Place the semi circular lever (1) between the
cams of the supporting ring (2) and slide the
dowel pin (3) into the (hinging) holes. Insert a
new split pin (4) into the hole at the end of the
dowel pin.

Fig.94
Fig.92
When the adjustment in situ of both tie
4. Insert the two M6 tie bolts (1) through the holes bolts has been done, provide both tie bolts
into the lever (2), the supporting ring (3) into the with the lock nuts. When locking, always
springs (4) and finally into the pressure ring (5). use two spanners to guarantee the
Screw the tie bolts into the nuts (6). adjustment.
Hint!
ADJUSTING THE VALVE LIFT
It is recommended to use a small
amount of loctite in order to maintain
adequate locking.
1. Check again whether the valve lift (5.0 mm) has

remained unchanged.
3.8 OIL PUMP AND OIL FILTERS

General
Fig.93
1. Place the suction valve ring on the push pins.

1.a. Tighten the nuts on the tie bolts in such a
way that the top of the suction valve ring
(in situ of the tie bolts!) is positioned 5.0
mm below the cylinder liner collar.
Fig.95

1. Place the pump on the working bench and Inserting a new pump element
unscrew the eight M6 fixing bolts (1) in the pump
cover out of the housing and remove the
washers (2) and the pump cover (3) with the
integrated pump element.
1.a. Remove the O-ring (4).
Fig.96
2. Remove the pump gear (5) from the crown wheel

(6) of the pump element/bearing assembly.
Fig.98
3. Clean the pump housing and the pump cover
with a non-fibrous cloth
1. Ensure that the bore and the contact face in the
Removing the pump element/bearing assembly pump housing are clean and oiled.
2. Place the pump housing with the bearing cover
fixing face in central position and pointing
downwards, using the pump cover(3)(!), under a
press.
Make sure the oil canals in the oil pump
assembly are aligned with the oil canals in the oil
pump housing.
The oil pump direction is determined by the
position of the cover.
3. Carefully press the pump element into the
Fig.97
housing with the cover until the contact face has
been clearly reached.
1. Place the pump housing with the pump cover Take care the positioning pin is aligned with the
fixing face in central position and pointing oil pump cover.
downwards under a press (take precautionary 4. Hint!
measures that the fixing pin, indicated with
arrow! does not break). Check that pump element can be
rotated by hand!
1.a. Place an auxiliary bush (B) with an outer
diameter øD < 60mm and an inner bore ød
> 45 mm over the crown wheel shaft. In
this position the pump element/bearing
assembly can easlily be pressed out with a
hydraulic press.

Fig.99: Carrier disc
5. Remove the carrier disc from the crankshaft

journal and check the condition of the slot and
the holes of the carrier disc.
Reassembling the oil pump
Fig.101: Pump detail
2. Slide the pump gear (5) onto the shaft (7) of the
Fig.100 pump cover (3).
2.a. Place the pump housing on its side and
1. Lightly oil all parts mentioned below before
insert the preassembled pump cover
reassembly!
element provided with a new O-ring in such
1.a. Insert into the housing: new O-rings in the a way that the fixing pin (P) fits into the
internal oil passageways, the plugs corresponding hole.
provided with new alu-washers, the
3. Tighten the eight M6 bolts (8) provided with
lubricating oil pressure regulator (1) in the
washers (9) in the pump housing to the torque
left-hand part of the housing and the
given in table “Survey of torques for bolts and
control pressure regulator (2) in the right-
nuts“(Chapter 5, Page 68).
hand part of the housing.
3.a. Check that the pump rotates smoothly; if
Hint! this is not the case, the pump element is
The shorter control pressure regulator not pressed far enough inside the oil pump
has a groove on the hexagon nut. The housing.
longer lubricating oil pressure 3.b. Place the preassembled pump in a
regulator does not have a groove. separate clean area to be mounted onto
the bearing cover later.

Filter elements 2.
Hint!
Filter elements can also be replaced
when the filter housings are still
mounted to the compressor.
Use special tool to remove oil filters
1. In order to reach the oil suction filter or oil

discharge filter element, only the lower housing
half has to be removed by supporting the
housing and unscrewing the grooved nut.
Fig.102: Oil suction and oil discharge filter
1.a. Pay attention to the residual oil in this filter

bottom
1.b. For a total inspection both the upper filter
housings can be removed from the pump
housing by unscrewing both M10 bolts.
1.c. Remove the filters as described
1.d. Whilst the the oil suction filter element is
cleanable, it shoul be replaced in case of
damage or serious pollution.
1.e. The red "running-in" oil discharge filter Fig.103
element is to be replaced by a grey one
after 100 running hours. Remove the O-rings (2 and 4) and the seal (3).
1.f. Renew a polluted grey-marked oil 2.a. Clean both filter housings (1 and 5) and the
discharge filter element. internal (connecting) passageways.
2.b. Insert each filter in the corresponding filter
housing and reassemble them with a new
set of seals3, a washer (3) and new O-
rings (2 and 4).
3 Only available as set under Ref. No. 09.90.030.

Hint! 1.b. Especially check those crankshaft parts

rotating in the bearing covers. Eliminate
In order to avoid damaging the seals,
slight damage using fine polishing paper.
the filter housing (5) should not
revolve together with the grooved nut 1.c. Check the thrust face (see arrow "A") on
(6). the collar of the bearing bush on oil pump
side for wear and replace it if one of the oil
Hint! grooves has virtually disappeared.
After having dis-assembled the Preassembling the bearing covers
discharge filter element, check this for
contamination, in particular for the 1. Bearing cover on driving side:
presence of aluminium and/or white
metal slide-bearing particles which
would require further investigation in
other parts of the compressor. In this
case, regularly check the oil quality by
means of an oil analysis.
Verwijderd nav wijzing oliepomp, KK, 8 mei 2008
3.9 MAIN BEARINGS

General
Fig.105: 42
2. When replacing a bearing bush, proceed as

follows:
3. Push or press (using a hydraulic press) the old
bearing bush out of the bearing cover.
3.a. Draw, for instance with a felt pen, a
longitudinally line and over the full length
on the outside of the new bearing bush
above the centre of the oil chamber.
Fig.104: 41
1. Check both main bearing bushes, while they are

in their respective bearing covers, for worn out
white metal inner lining.
1.a. Replace the bush(es) if the inner lining
shows abnormal wear and also if the bore
is over 90.16 mm. Fig.106: 43

4. Oil the bearing bush and place it with the internal 3. Oil the bearing bush and position it above the
chamfer facing upward and above the bore in the bore in the bearing cover, so that the line drawn
bearing cover in such a way that the oil with the (felt) pen is in the centre of the locking
passageway is in the centre of the locking pin. pin.
4.a. Slowly press the bearing bush (using a 3.a. Slowly press the bearing bush (using a
hydraulic press) into the bearing cover, hydraulic press) into the bearing cover,
making sure that the bearing bush is not making sure that the drawn line is not
displaced. displaced, in order for the locking pin on
the left-hand side (projecting 3 mm above
1. Bearing cover on pump side; the bearing cover) to be pressed entirely
into recess "A".
Fig.109: 46
Fig.107: 44 4. Inspect the intermediate bearing(s) for visual

wear and for possible scoring of the white metal
When the bearing bush requires replacement, inner lining and collar bearings.
proceed as follows: 4.a. Assemble the intermediate bearing(s) with
2. Push or press (using a hydraulic press) the old the stamped-in numbers on one side and
bearing bush out of the bearing cover. tighten the intermediate bearing bolts.
2.a. Draw a longitudinal line, for instance with a 4.b. Measure the inside diameter and replace it
felt pen, on the outside of the new bearing when it is over 90.14 mm.
bush from the centre of recess "A" (to the
left of oil chamber "B") as far as the
collarless end. 3.10 ROTARY SHAFT SEAL
Hint!
Avoid touching the carbon part!
Preferably rub your hands with oil or
wear gloves.
Fig.108: Bearing cover with mounted splash guard

3.11 CRANKSHAFT
General
Fig.112: 49
1. Only with 2 cylinder compressors, remove the

Fig.110 spacer (compensating mass) from the crankshaft
and reassemble both halves into a whole,
1. Remove the O-ring (3a) from the counter slip separately from the crankshaft.
ring (3) and the O-ring (2a) in the rotating ring
(2).
1.a. Check the sliding surfaces of the counter
slip ring (3) and the rotating ring (2) for
wear or damage.
1.b. Clean the housing (1) and all other parts.
1.c. When one of the sliding surfaces is
affected, replacement of both parts is
required.
1.d. Renew all O-rings (1a, 2a and 3a).
Fig.113: 50
2. Thoroughly clean the entire crankshaft:

2.a. Check whether the axially fitted oil
passageways in the crankshaft are
unobstructed by cleaning them with
compressed air or a brush.
2.b. In order to be sure that the passage of
lubricating oil within the crankshaft is
unobstructed, unscrew the socket head
screws (locked with centre punches) out of
the crankshaft webs.
2.c. Remove the dirt accumulated in the oil
Fig.111 passageway (in the case of damage to
bearings white metal particles) with a 6 mm
bar.
2. Renew the entire shaft seal in the case of
damage or wear of the slip ring. 2.d. Brush and blow out the crankshaft again
until all oil passageways are unobstructed.
2.e. After cleaning, reassemble all oil
passageway sealing bolts (socket head
screws) and lock them with centre
punches.

Fig.114: 51
3. Check the diameters of the shaft journals and

shaft ends with an outside micrometer in at least Fig.116: 53
2 directions and dead square to the measuring
surface. 2. In the case of a 2 cylinder compressor, fit the
3.a. Here measure "A" should be at least spacer onto the crank web on the driving side
89.933 mm and measure "B" 89.945 mm. using two M8 bolt/nut joints and tighten these to
the torque as given.(refer Chapter 5, Page 68)
3.b. Should these measurements show that the
shaft diameter(s) is (are) beyond the
tolerance limits and there is any doubt 3.12 THRUST BEARINGS
about the serviceability of this crankshaft,
then the shaft should be replaced. Besides a standard mounted thrust bearing, a heavy
duty thrust bearing can be mounted (optional)
Preassembling the crankshaft
3.12.1 STANDARD BRONZE THRUST

BEARING, MARK 2
Hint!
Refer Section 2.10, Page 25
Fig.115: 52
1. In the case of 4, 6, 9 and 12 cylinder

compressors, place the shells of the intermediate
bearings into the bearing block(s).
1.a. Oil both bearing shells well and fit the
intermediate bearing(s) on the crankshaft
(intermediate bearing halves with stamped-
in numbers on one side).
1.b. Tighten the four M16 bolts to the torque
given.(refer Chapter 5, Page 68)
1.c. Check that the intermediate bearing(s)
Fig.117: Standard bronze thrust bearing; refer also Figure 38,
freely revolve(s) around the crankshaft. Page 25
1. Clean the thrust bearing and check the lapped

running surface on the bronze side for
(ir)regularly worn oil grooves and for material
deposits.
1.a. Replace this thrust ring if it shows signs of
wear and when the thickness is less than
5.50mm.

3.12.2 HEAVY DUTY THRUST 1.d. Do not forget to remove the packing
BEARING remains from the flanges of the main
connections of the compressor!
Fig.118: Heavy duty thrust bearing
Fig.120
1. Clean all thrust bearing parts. Check all running
surfaces which are in contact with the cylindrical 1. Remove the oil return plug from the lowest
roller thrust bearing and the needle thrust landing of the cylinder jackets for the LP
bearing for (ir)regular wear and other damage cylinders {see left plug in Fig.}
such as pits, marks or scratches.
1.a. Inspect the return plugs, clean them and
1.a. Replace the complete heavy duty thrust tighten them after refitting.
bearing set when the rollers, needles or
1.b. The plug for the HP cylinders {see right
running surfaces show signs of wear.
plug in fig.} does not need inspection and
can therefore remain fitted.
3.13 CRANKCASE
Fig.119
1. Thoroughly clean the crankcase interior and dry

it with a non-fibrous cloth.
1.a. Inspect all exterior packing faces and
remove possible residual packing particles.
1.b. Thoroughly blow through all connections
on the inside and on the outside.
1.c. Clean the sight glass.

4 REASSEMBLING
Warning!
All bolts and nuts have to be mounted
according to to the torques as given in
table “Survey of torques for bolts and
nuts" as available in this manual. If
you cannot find this information,
consult Grasso.
Hint!
All O-rings have to oiled before
assembling. Refer Section 5.8,
Page 78.
Fig.122
2. Place the bearing cover on the driving side in

4.1 CRANKSHAFT, MAIN BEARINGS such a way that the hole in the lug of the bearing
AND INTERMEDIATE BEARING cover is opposite the internal oil passageway
pipe.
2.a. Then slide the bearing cover over the
4.1.1 Bearing cover driving side crankcase studs.
2.b. Screw all M16 nuts provided with washers
on the studs and tighten them alternately
and crosswise to the torque given in
(Chapter 5, Page 68).
4.1.2 Assembly procedure of 2 and 3

cylinder compressors
1. Insert the crankshaft (with/without

counterweights) through the crankcase opening
on the oil pump side into the bearing cover.
Fig.121
4.1.3 ASSEMBLY PROCEDURE 4, 6,

1. Place a new O-ring on the inner side of the 9 AND 12 CYLINDER
bearing cover.
COMPRESSORS

Fig.123 Fig.125
1. With assistance and using auxiliary tools, insert

the crankshaft (with/without counterweights4)
through the crankcase opening on the pump side 4.1.5 Bearing cover oil pump side (with
into the crankcase. The crankshaft now rests on two lugs):
the intermediate bearing block(s).
1.a. Remove the auxiliary tools, clean the shaft 1. Place a new O-ring on the inner side of the
journals and oil them. bearing cover.
1.a. Place a new O-ring on both pipes of the
internal oil passageway Figure 124,
4.1.4 Pump side Page 52.
Fig.126
Fig.124
2. Place the cover in such a way that the holes in

1. Place a new O-ring on the pipe of the internal oil each lug of the bearing cover are opposite the
passageway. pipes of the internal oil passageways and slide
the bearing cover over the crankcase studs.
4 For mounting the counter weights see further on in this

chapter "Assembling counter weights".

Fig.127 Fig.129
3. Screw all M16 nuts provided with washers on the 2. Check that the crankshaft boss is still clean and
studs. oiled.
4. Finally tighten the nuts alternately and crosswise 2.a. Fit the hold down disc onto the crankshaft
to the torque given(Chapter 5, Page 68). boss, using the four M10 socket head
screws with the torque given(Chapter 5,
4.a. Check that the crankshaft rotates freely.
Page 68).
2.b. Check that the crankshaft rotates freely.
4.1.6 Standard thrust bearing
4.1.7 Heavy duty thrust bearing

The reassembling of the heavy duty thrust bearing is
split into two parts, the heavy duty thrust bearing
itsself and the oil pump.
1. 1st step; Heavy duty thrust bearing
2. Check whether all components are clean,
including the inside of the bearing cover and
crankshaft on oil pump side.
Warning!
Check the crankshafts top surface on
oil pump side for having installed the
closed M12 plug, without orifice.
Fig.128: Standard thrust bearing; refer also Figure 38, Page 25
1. Fit the oiled thrust ring with the oil grooves

directing outwards on the crankshaft on oil pump
side in such a way that the locking pin in the
bearing cover fits into the hole in this thrust ring
surface.
Fig.130: Heavy duty thrust bearing

Hint! 13.a. The opening of the holes should be pointed

to the outside of the oil pump housing.
Pos. 1, 2, 4, 5, 6 and 7 can be mounted
together in any crankshaft angle 14. Insert the oiled springs (9) in the holes of the
spring retainer (8).
3. Fit the oiled 1 mm. thick thrust washer (7) on the
crankshaft on oil pump side. 15. Place a new O-ring on the inner side of the fully
pre-assembled oil pump.
3.a. The thrust washer (7) can be used on both
sides. 16. Slide the oil pump over the studs of the bearing
cover.
4. Fit the oiled cylindrical roller thrust bearing (6) on
the crankshaft on oil pump side. 17. Position the carrier lug of the pump element with
the slot in the carrier disc.
4.a. The cylindrical roller thrust bearing (6) can
be used on both sides. 17.a. Pay at all times attention not to dislodge
the springs (9) or the spring retainer (8).
5. Fit the oiled shaft washer (5) on the crankshaft
on oil pump side. The shaft washer if recessed to 18. Push the oil pump as far as possible towards the
fit exactly around the crankshaft. bearing cover and screw the M12 nuts with
washers on the studs.
6. Fit the oiled hold down disc (4) into the shaft
washer (5), using the four M10 socket head 18.a. The oil pump cannot be pushed fully
screws (3) with the torque given(Chapter 5, against the bearing cover, because of the
Page 68). springs and will only seat correctly when
the nuts are tightened
6.a. Check that the crankshaft rotates freely.
18.b. Check all springs to be present and in
7. Fit the oiled needle thrust bearing (2) on the hold place.
down disc (4).
19. Reinstall the external oil line. It is connected from
7.a. The needle thrust bearing (2) can be used the top of the oil pump to the service cover.
on both sides.
8. Mate the oiled 7 mm. thick housing washer (1)
against the needle thrust bearing (2). 4.1.8 Measuring the axial crankshaft
play
8.a. The housing washer (1) must be mated
with its running surface against the needle Procedure for 2 and 3 cylinder compressors
thrust bearing (2), it can not be used on
both sides.
9. 2nd step; oil pump for heavy duty thrust
bearing
10. Place the carrier disc (10) on the hold down disk
(4).
10.a. The chamber of the slot of the carrier disc
(10) must face the crankshaft.
Hint!
Position the slot of the carrier disc (10)
in vertical or horizontal position by
rotating the crankshaft
Fig.131
11. Place 2 new O-rings around the oil inlet- and
outlet holes at the bearing cover (11). 1. For this measurement a magnet (clock) gauge
with an extended gauge can be set up on the
12. Check that the oil pump is clean.
bearing cover.
13. Place the oiled spring retainer (8) in the pump
housing counter bore.

1.a. Remove a stud and screw in the M12 eye

bolt.
1.b. Screw another eye bolt into the threaded
hole on the crankshaft.
1.c. Pull out the crankshaft and set the gauge
on 0.00 (zero).
1.d. Push the crankshaft inwards and check/
write down the axial play on the gauge.
For every compressor the play is determined
between 0.05 and 0.85 mm.
Contact the service department of Grasso if the
Fig.133
axial play is not within the tolerance limits.
2. If there is no clock gauge available, the axial play

4.1.9 Procedure for 4, 6, 9 and 12 in situ of the collar bearing can also be
measured with the help of feeler gauges. Here
cylinder compressors
again the axial play is measured by the
difference between the pulled out and pushed in
crankshaft (see also measuring procedure with
clock gauge).
4.1.10 Assembling counter weights
Fig.132
1. Measure the axial play proceeding in the same

way as for the 2 and 3 cylinder compressors.
1.a. Position the intermediate bearing block(s)
and fit handtight the 2 sets of toothed
Fig.134
spring washers and the M20 bolts in the
cross frame.
1. Fit the counterweights with new locking rings and
1.b. Check that the crankshaft rotates freely. bolts onto the crankshaft if dismantled.
1.c. Subsequently, firmly tighten the bearing 2.
block(s) after the intermediate bearing(s)
has(ve) been adjusted in accordance with Hint!
the drawing (measure "=" + 0.5 mm) Pay attention to numbers and marks!
(Figure 132, Page 55).
Counterweights are not
1.d. Further tighten the intermediate bearing interchangeble!
bolts to the torque given(Chapter 5,
Page 68). 3.
4. Fit the double locking rings in the proper
position!

5. Tighten the bolts with a torque wrench to the

torque given(Chapter 5, Page 68).
4.2 OIL PUMP
Fig.136
2.b. Position the carrier lug of the pump

element with the slot in the carrier disc.
2.c. Push the oil pump fully against the bearing
cover and screw the M12 nuts with
Fig.135 washers on the studs.
2.d. Tighten all nuts evenly and crosswise to
1. Place the carrier disc on the hold down disc. the torque given.
Hint!
The chamber of the slot of the carrier 4.3 OIL SUCTION FILTER, OIL
disc must face the crankshaft. DISCHARGE FILTER,
LUBRICATING OIL PRESSURE
Hint!
REGULATOR AND CONTROL OIL
Position the slot of the carrier disc in PRESSURE REGULATOR
vertical or horizontal position by
rotating the crankshaft.
2. Place a new O-ring on the inner side of the fully 4.3.1 Oil discharge filter
pre-assembled oil pump.
2.a. Slide the oil pump over the studs of the
bearing cover.

Fig.138
1. Install the lubricating oil pressure regulator with a

Fig.137 new aluminium ring on the left-hand side of the
pump.
Hint! 2. 2.a. Finally fit the cap nut handtight on the

regulator using a new alu-ring.
After the first 100 operating hours the
red-marked discharge filter has to be Hint!
replaced by a grey-marked filter Final adjustment of a reassembled
element! lubricating oil pressure regulator can
1. Fit the preassembled (red5/grey) marked be done during compressor operation.
This adjustment procedure is
discharge filter using the two M10 bolts with
described in the Installation and
washers on the right-hand side of the pump.
Maintenance Manual.
1.a. Tighten the bolts to the torque
given(Section 5.1, Page 68).
4.3.4 Control oil pressure regulator
(with groove)
4.3.2 Oil suction filter
1. Install the control pressure regulator with a new
1. Fit the preassembled (marked blue) suction filter
aluminium ring on the right-hand side of the
using the two M10 bolts with washers on the left-
pump.Figure 138, Page 57
hand side of the pump.
1.a. Finally fit the cap nut handtight on the
1.a. Tighten the bolts to the torque
regulator using a new alu-ring.
given(Section 5.1, Page 68).
Hint!
Final adjustment of a re-assembled
4.3.3 Lubricating oil pressure regulator control oil pressure regulator can be
(without groove) done during compressor operation.
This adjustment procedure is
If not built in yet; described in the Installation and
Maintenance Manual.
5 Always fit a new red-marked oil discharge filter element

into a modified plant.

4.4 Replacement piston rings and Therefor: Never install new pistons with new piston
cylinder liners rings in old cylinder liners. It is strongly
recommended to replace the cylinder liners too.
Hint!
Recommendation/warning!
For major overhauls or every repair
where piston rings are being replaced
it is strongly recommended to replace
the cylinder liners as well. This is very
important for the next reasons:
For the best sealing between piston rings and

cylinder liners, piston rings have to run in on the
cylinder liner’s inner surface. Therefor a new cylinder
liner with a honing profile (crosshatching) in the best
condition is absolutely required. Piston rings cannot
run in properly on worn out or partly worn out
cylinder liners. Without a decent honing profile no Fig.140: Don't use new piston rings on old cylinder liner
proper sealing between liners and rings can be
N Shape of new piston ring (sharp)
achieved which may result in- or contribute to a bad
O Shape of old piston ring (rounded)
performance of the compressor. Further on, this
honing profile with the right crosshatching is
demanded for a good lubrication between piston
rings and liners and for the right oil distribution on the
liner’s inner surface. 4.5 CYLINDER LINER
1. Examine the thickness of the gasket which was

originally placed on the lower landing of the
cylinder jacket and under the cylinder liner collar.
1.a. Select a new gasket of the same thickness,
being 1, 1.25 or 1.5 mm.
1.b. Check that the gasket face of the cylinder
jacket is still clean and place the greased
Fig.139: New honing profile and crosshatching with the right
gasket into the landing.
angle
1.c. Write down the thickness of the gasket on
the outside of the cylinder jacket.
After being in operation for many running hours
cylinder liners and piston rings will wear out and 2. Draw a line from the centre of the valve-lifting
most cylinder liners will become unworn ridges lever up to the cylinder liner collar.
(bumper rims or edges) due to the displacement of 2.a. Place the cylinder liner above the cylinder
the piston rings inside the liner. The upper unworn jacket.
ridge occurs at the upper death end and upper side
2.b. Position the line drawn on the cylinder liner
of the upper piston ring and the lower ridge occurs at
the death end of the lower side of the lower (oil with the flange centre (mounting face of
scraper) ring. In many cases intermediate and oil valve-lifting housing) on the outside of the
scraper rings cause their own bumper ridges. cylinder jacket.
(Bumper steps) Also, both upper and lower edge are 3. 3.a. Lower the cylinder liner as far as possible
set by the worn shape of the piston rings. This into the cylinder jacket.
clearly explains why new piston rings can break
when used in old/worn cylinder liners due to hitting
the unworn bumper ridges at high speed. (See also
picture below)

4.6 PISTON/CONNECTING ROD

ASSEMBLY
Fig.141
Fig.143
1. Slide the connecting rod bolts into the big end of

the connecting rod (make sure that the flat side
is positioned correctly!).
1.a. Place the bearing shells into the
connecting rod cap.
1.b. Oil bearing shells, piston and piston rings.
1.c. Slide the ring compression bush7 with the
chamfered end pointing downwards over
Fig.142 the connecting rod, the piston and the first
oil scraper ring in such a way that this oil
3.b. Place the short green bar6 on the upper scraper ring is only just visible.
cylinder liner collar and the long green bar 1.d. Oil and set the relevant crankshaft journal
over 2 cylinder head studs. in the uppermost position of the cylinder
3.c. Fix the long bar with two M16 nuts and centre.
place a steel disc on the threaded hole in 1.e. Screw the T-handle (from the auxiliary tool
the lower bar to protect the threaded hole kit) into the threaded hole of the piston.
from damaging.
3.d. Screw the long M24 bolt into the long bar
and tighten it turning clockwise until the
cylinder liner is fully seated in the inner
landing of the cylinder jacket.
3.e. Remove the auxiliary tools.
Hint!
Check that the inserted cylinder liner
is positioned properly by comparing it
with the other cylinder liners that were
assembled earlier. Check the valve
lifting action with compressed air. Fig.144
Make sure that the cylinder liner does
not rotate!
6 Parts of the auxiliary tool kit. 7 Parts of the auxiliary tool kit.

2. Insert the piston/connecting rod assembly into 4.7 DETERMINING THE PISTON
the cylinder liner. CLEARANCE
2.a. Lower it very carefully until the ring
compression bush strikes the cylinder liner
and after that slowly push on until the
piston is almost entirely located inside the
cylinder liner.
2.b. Check that the connecting rod properly
embraces the crankshaft journal. If so,
push through to the crankshaft journal and
check that the bearing shell in the
connecting rod has not been displaced.
Fig.146
1. Place a solid 2 mm thick lead or tin soldering

wire which has been shaped to fit into the
threaded hole of the piston and laid parallel with
the crankshaft or gudgeon pin.
Fig.147
2. Oil the discharge valve assembly and place it on

the cylinder liner.
2.a. Place the bar from the auxiliary tool kit on
the studs as well as on the discharge valve
centre.
Fig.145
2.b. Screw two M16 nuts on the studs .
3. Slide the corresponding connecting rod cap over 2.c. Screw the M24 push bolt into the long bar
the connecting rod bolts. and after that revolve the crankshaft two or
three times.
Hint!
Fit the connecting rod parts with the
machine codes on one side.
3.a. Fit both MF16 nuts with new (double)

locking rings on the connecting rod bolts
and tighten to the torque given.

Fig.148 Fig.150
3. Remove all measuring aids and measure the

thickness of the flattened wire. This thickness,
which is equal to the clearance, should be at
least 1.05 mm and at most 1.45 mm. If the
measuring result is beyond these limits, it is
necessary to remove the piston/connecting rod
again and replace the sealing ring under the
cylinder liner collar by a thicker or thinner one,
according to whether the clearance was too
small or too large.
4.8 VALVE-LIFTING CONTROL

MECHANISM
Fig.151
Legend
A Distance when assembled 4 to 5 mm
B Semi circular lever

Fig.149
C Cylinder jacket
1. Place the pressure pin into the bore of the plug
screwed into the cylinder jacket. D Alu ring
E Plug
F Pressure pin
2. When assembled, distance A must be 4 to 5

mm.

3. Put the valve-lifting housing with in-built piston

back into its original position on the flange of the
cylinder jacket.
3.a. Tighten the four M10 bolts in the cylinder
jacket to the torque given(Section 5.1,
Page 68).
3.b. Connect the 8 mm control pressure oil line
to the housing.
4.9 SUCTION/DISCHARGE VALVE

ASSEMBLY Fig.153: Top view of discharge valve assy
1. Place the suction valve ring on its seat in the 3. Place the preassembled discharge valve
cylinder liner collar. assembly on the sinusoidal springs of the suction
valve.
3.a. Clean the sealing edge of the cylinder
head cover and also the edge on the
cylinder head itself.
3.b. Rub both packing faces and the studs with
grease.
Fig.152: Top view piston
2. Place the sinusoidal springs with the convex side

pointing upwards on the suction valve ring.
Hint!
During the assembly the sinusoidal
springs in inclined cylinders can fall Fig.154: Top view of discharge valve assy
out of the cylinder liner. This can be
prevented by placing the sinusoidal 4. Place the oiled pressure spring cup on the
springs in such a way on the valve discharge valve assembly.
ring that the springs touch the valve
ring at the highest and the lowest
point in the inclined cylinder liner.

Fig.155: Top view buffer spring Fig.157: Top view cylinder cover
5. Subsequently, fit the buffer spring which has to 6.c. Tighten these two nuts alternately to the
be prevented from tipping by a steel strip placed torque given(Section 5.1, Page 68).
against the two studs.
6.d. After that, fit the other nuts in the same
6. Insert a new gasket into the cylinder cover way.
groove and slide the cylinder head cover over
the studs on the buffer spring.
4.10 ROTARY (SLIP RING) SHAFT
SEAL
Fig.156: Top view cylinder cover
6.a. Remove the strip.

Fig.158: 40
6.b. Screw two M16 nuts on the two long and
oiled studs.
1. In the case of new parts, check that the
protective foil has been removed.
1.a. Avoid touching the contact faces of these
parts; slightly rub your hands with oil or
wear gloves.
1.b. Especially inspect the crankshaft part
where the O-ring moves.
1.c. Remove all (rubber) deposit by sanding or
polishing.
1.d. Oil all parts with compressor lubricating oil,
as well as the crankshaft part in situ of the
shaft seal.

1.e. Slide the slip ring part over the crankshaft

and push through until the rear side is
positioned against the crankshaft boss.
Fig.161: 43
4. Place the M12 nuts and tighten them alternately

Fig.159: 41 crosswise to the torque given.
4.a. Screw the nipple coupling for the oil
2. Lock the slip ring on the crankshaft by tightening leakage drain line into the bottom of the
the three grub screws with an allen key8. shaft seal housing and then the drain line.
(Torque refer Section 5.1, Page 68)
Fig.162
Fig.160: 42
5. Check that the crankcase is clean and dry and,
3. Insert the counter slip ring with the O-ring into subsequently, fit all crankcase covers with new
the shaft seal housing. O-rings.
3.a. Place a new O-ring into the groove of the
cleaned shaft seal housing.
3.b. Mount the shaft seal housing (only one
mounting position is possible) onto the
crankcase.
8 Part of the auxiliary tool kit.

4.11 SUCTION GAS FILTER

Hint!
Refer to the valve position table
(Section 5.7, Page 74) for the
location of pressure relief valves.
1. Place a new O-ring in (each) pressure relief

valve housing.
1.a. Put the pressure relief valve housing into
the proper mounting position (only one
mounting position is possible!) against the
cylinder jacket.
Fig.163 1.b. Screw the six M12 bolts into the cylinder
jacket and tighten them evenly and
crosswise to the torque given(Section 5.1,
1. Place a new gasket into the groove of the Page 68).
suction gas filter cover.
1. 1.a. Slide the preassembled cover of the

suction gas filter assembly into the housing
4.13 Running-in oil filter has to be
in such a way that the centring profile installed after an overhaul or big
around the filter fits into the fixed centring repair
edge.
Hint!
1. Screw the eight bolts into the housing and
This is why and when the running in
tighten them to the torque given(Section 5.1, oil filters are required:
Page 68).
Warning!
A running in oil filter has always to be
4.12 PRESSURE RELIEF VALVE
installed after an overhaul or big repair
ASSEMBLY
for the 1st 100 hours of operation!
The oil and oil oil filters have to be
replaced by new oil and filters.
Due to running-in wear of liners and
piston rings, it's normal that the oil
becomes grey during the 1st 100
operating hours.
After 100 operating hours, the oil
could slightly become clear again.
4.14 OIL FILLING

Fig.164: Relief valves
Hint!
Legend Use clean or fresh original oil only!
1 Back pressure dependent 1. The following components have to be filled with

oil before starting up via the oil charge valve,
2 Back pressure independent mounted on the oil pump, refer Figure 166,
Page 66:

1.a. Crankcase
Quantity of oil
1.b. Shaft seal housing(Figure 165, Page 66)
1.c. Oil pump QUANTITY OF OIL TO BE FILLED (IN dm3)
1.d. Oil discharge filter

Shaft seal
1.e. Oil lubrication circuit housing
Oil Oil
Number of incl. Crankc
2. Oil suction filter(Figure 166, Page 66 ,left filter): filte pu
cylinders internal ase
Charge through the filling openings or rs mp
circuit of
prelubricating valves (if present) on the top of the
crankshaft
filter housing.
2
0.63 7.8
3
4 0.72 1.5 13.6

eac 0.5
6 0.73 h 14.7
9 0.83 21.7
12 0.93 28.7
Fig.165: Shaft seal housing
4.15 MOUNTING FLYWHEEL
Fig.166: Oil filters and location oil charge valve (A); not shown!
3. Oil discharge filter: Fig.167

Remove all oil filling plugs and fill the
corresponding components with the amount of 1. Place the flywheel on the crankshaft using a
oil given(Page 66). suspension gear with sling.
3.a. Fit the oil filling plugs with new aluminium
rings.
3.b. Fit the other nipples and couplings and tap
the key into the crankshaft key way.

Fig.168 Fig.171
2. Place the locking disc and screw the centre bolt 5. Lock the central bolt with locking plate, together
as far as possible into the crankshaft. with the fourth M12 bolt.
4.16 DISCHARGE VALVES, LEAKAGE

TEST PROCEDURE
A leak test after 4 running hours of the compressor is
strongly recommended;
1. Stop compressor
2. Immediately close the discharge stop valve and
record the discharge pressure (must be at least
6 bar)
Fig.169 3. Measure the time it take for the discharge
pressure to fall to 3 bar. (decrease from 6 to 3
3. Screw three (3) M12-bolts fully into the flywheel bar)
hub. Warning!
If equalizing time is less than 60
seconds, all the discharge valves have
to be checked.
Fig.170
4. Tighten the central M24-bolt with a torque

wrench to the torque given(Section 5.1,
Page 68).

5 MISCELLANEOUS
5.1 SURVEY OF TORQUES FOR To

BOLTS AND NUTS I rq
Thre
t ue
Threaded connection ad Remarks
e in
size
m N.
To m.
rq
I
Thre ue
t Discharge valve (centre 12
Threaded connection ad in Remarks 9 M16
e bolt) 0
size N.
m
m.
9 1 12
Cylinder head nuts M16
0 0
Bearing cover nuts (both 12

1 M16 1 Cylinder liner tie bolt -
sides) 0 M6 ---
1 nut
tig
1
Coupling bearing cover G1/4 hte Sight glass flange bolts M6 7
2 2
on pump side ” ne
d
1 Crankcase side cover
M12 80
3 bolts
3 Shaft seal housing nuts M12 40
1 Pressure relief valve
4 M12 80
4 cover bolts
. Oil pump housing bolts M12 40
1
Pressure relief valve
1
assembly mounting M12 80
4 5
bolts
. Pump element bolts M6 7
2
1
Oil discharge filter bolts M10 35
6
MF1
10
5 Connecting rod bolts 6x1.
0 1
5 Oil suction filter bolts M10 35
6
Gudgeon pin locking
6 M12 40 Suction filter housing
bolt 1
bolts 2, 3 and 4 cyl. M12 40
8
compressor
Valve-lifting housing
7 M10 35
bolts
Suction filter housing
1 12
bolts 6, 9 and 12 cyl. M16
tig 9 0
compressor
Coupling of the control G1/8 hte
8
line valve-lifting housing ” ne
2 12
d Bearing block bolts M16
0 0
9 1 N.m = 0,102 kgf.m = 0,738 lbf.ft

To To
rq I rq
I Thre
Thre ue t ue
t Threaded connection ad Remarks
Threaded connection ad in Remarks e in
e size
size N. m N.
m
m. m.
9
tig
tig 3 G1/2 hte
Sealing plug
2 Intermediate bearing hte 0 ” ne
M20 d
1 block bolts ne
d
ha
2 12 3 Hand nut suction/ M90 ndt
Counterweight bolts M16 1 discharge filter x3 igh
2 0
t
2 Crankshaft spacer ring 17.
M8 3 Threaded rod auxiliary
3 bolts 5 M12 ---
2 tool
Standard and heavy
2 duty thrust bearing tig
M10 35 3 Lubricating oil pressure hte
4 (pressure piece) socket M27
head screws 3 regulator - hexagon ne
d
ha
2 Shaft seal (locking) ndt tig
M4 3 Control oil pressure hte
5 screws igh M27
t 4 regulator - hexagon ne
d
2 Socket head screw of
M5 5.5 ce
6 disc/lever
ntr
tig 3 e
Crankshaft sealing plugs M8
2 Coupling leakage drain G1/8 hte 5 pu
7 shaft seal ” ne nc
d h
2 tig
Oil splash plate bolts M6 7 3 Non-return valve in hte
8 M22
6 cylinder liner collar ne
tig d
2 G1/4 hte
Sealing plug tig
9 ” ne
d 3 Tapered plug in cylinder G1/4 hte
7 liner collar ” ne
d
3 Push bolt from auxiliary

M24 ---
8 tools
9 1 N.m = 0,102 kgf.m = 0,738 lbf.ft

Hint!
To Not only the wear limits determine
rq whether a part is to be replaced, but
I moreover the condition of the part;
Thre ue
t have the honing or grinding tracks of
Threaded connection ad in Remarks
e precision machined butting or running
size N.
m faces been worn off irregularly, are
m.
9 there any visible discolouring of
material, has the roundness remained
3 Pulley puller for shaft correct and are there any signs of
M8 --- glazing. All these wear factors make a
9 seal
part virtually unserviceable, even if
this part remains within its wear limits.
tig
4 hte
Foundation bolts M20 Wear limits and tolerances
0 ne
d
I
refer to t Description of Re Limits
Remarks
service e part f. (mm)
4 instreucti m
Drive coupling bolts
1 on
00.87.53 20. max.
7 Main bearing 38. inside
1 When fitted
bush pump side 11 diam.
tig 0 90+0,16
4 hte
Hub securing bolts (4x) M12
2 ne 20. max.
Main bearing
d 38. inside
2 bush driving When fitted
10 diam.
side
4 Hub securing (centre) 40 2 90+0,16
M24
3 bolt 0
11. max.
Bearing bush
15 46. inside
3 small end of the When fitted
4 - 65 diam.
Shaft seal - Crankshaft M6 connecting rod
4 18. 2 50+0,14
3
20. max.
Bearing shell
38. inside
4 big end of the When fitted
14 diam.
connecting rod
5.2 WEAR LIMITS AND TOLERANCES 0 90+0,14
Crankshaft min.
22.
(main bearing outside
5 39.
and crankshaft diam.
....
journal) 90-0.07
min.
Crankshaft 22.
outside
6 (intermediate 39.
diam.
bearing) ....
90-0.05
9 1 N.m = 0,102 kgf.m = 0,738 lbf.ft

Wear limits and tolerances Wear limits and tolerances
I I
t Description of Re Limits t Description of Re Limits
Remarks Remarks
e part f. (mm) e part f. (mm)
m m
min. 11.
22. min.
Crankshaft 0.05 / 1 42.
7 39. When fitted Thrust ring thicknes
(axial play) max. 6 01
.... s 5.50
0.85 2
max. 03. max.

23. Bore in plug
inside 1 04. inside
18. control When fitted
8 Cylinder liner diam. When fitted 7 51 diam.
01 mechanism
160+0.1 4 14.07
0
2
11. max.
24. min. 1 31. 115,
Buffer spring
18. outside 8 18 min.
9 Gudgeon pin
32 diam. 1 110
0 50-0.00
09. Measured in
max.
1 74. non-scored
Piston rings gap
0 16 part of cylinder
2+0.1
0 liner
11.
min.
1 Suction valve 34. In situ of
thicknes
1 ring 17 scoring of seat
s 0.8
1
11. min.
1 Discharge valve In situ of
34. thicknes
2 ring scoring of seat
..... s 0.8
20. min.
Control
1 38. outside
pressure piston
3 13 diam.
for valve lifting
4 51-0.08
27. max.
Control
1 38. inside
pressure piston
4 65 diam.
housing
0 51+0.07
11. max.
1 Intermediate 44. inside
When fitted
5 bearing 89 diam.
0 90+0.14

5.3 REQUIRED SERVICE TOOLS AND

MATERIALS
Description
In order to properly carry out the disassembly,
inspection and assembly procedures described in Circlip pliers
this manual, the service engineer should possess the
following tools, measuring equipment and aids. Hammer (steel)
Hammer (soft)
Description
Remove split pin valve-lifting
Pair of pliers
mechanism
8-10 (2x)
Ring spanners and socket
-13-14-17-19-24-27-30-32-36 Loctite 243
spanners (metric):
-41
Lead or tin soldering wire for measuring piston
-Spanners:
2 mm clearance
Hexagon socket head
8-13-10-17
spanners (metric):
Polishing paper
Torque spanners (metric) 19-24-30-36

Polishing (compound)
paste
Pin-face wrench (metric)
M4
for shaft seal
(two) Screwdrivers (small) e.g. for removing shaft seal
Screwdiver (large) removing key

Inside micrometer of 0-50
mm
Abrasive linen
Inside micrometer of Silicon grease

50-100 mm
Wire brush
Outside micrometer of
0-50 mm Piston ring pliers
-Measuring
equipment:
Outside micrometer of Grease

50-112 mm
Self-made (crankshaft) removing and inserting
Depth micrometer of 0-50 auxiliary tool crankshaft
mm
Auxiliary tools for shaft
Vernier gauge of 10" seal
Feeling gauges of Steel strip support buffer spring

0.05-1.00 mm
Oil drip tray
Magnetic gauge with
extended plunger
cleaning crankshaft oil
Tube brush ø10 mm
passageways
Grasso special tool kit TA various service activities cleaning crankshaft oil
Bar ø6 mm
passageways
Misc:
cleaning e.g. crankshaft oil

Vacuum pump Compressed air device
passageways
Centre punch

5.6 MASS OF SEPARATE

COMPONENTS AND
Description
COMPRESSORS
Hydraulic press
removing and inserting Ma

Heater approx. 80 °C
connecting rod bearings Description ss Remarks
(kg)
Bearing cover drive end 22.

5.4 GRASSO SPECIAL TOOLS AND (assembly) 2
AIDS
Bearing cover oil pump 22.
Certain operations which requires fitting and
end 5
removing pistons and cylinder liners can be
substantially be simplified by using special tools and
Mind the
aids which are obtainable as standard auxiliary tool
remaining oil still
kit, ref. no. 20.38.010 and instruction 00.87.121. Oil pump housing, 28.
present when
complete with filters 2
removing the oil
pump housing!
5.5 FITTING INSTRUCTIONS FOR
PIPE COUPLINGS AND DOUBLE 11.
LOCKING RING Cylinder liner assy
7
Intermediate bearing 10.

assy 2
number of
-
cylinders
54.
2
0
57.
3
5
With the
Fig.172: Pipe couplings 66. assistance of a
Crankshaft 4
5 second person
and using
81. auxiliary tools the
6
0 crankshaft can be
removed or fitted.
124
9
.0
Fig.173: Double locking ring
145
12
.0

Ma
Description ss Remarks
(kg)
Careful when
removing! The full
13.
Relief valve assy weight is
0
released all at
once.
For weights of bare shaft compressor and flywheel,

refer to Product Information (ED).
5.7 RELIEF VALVE POSITIONS
Fig.175: Relief valve; Back pressure dependent
Fig.174: Relief valve; back pressure independent

Relief valves NH3 Relief valves NH3
Relief valve positions per cylinder number Relief valve positions per cylinder number
(LP = Low Pressure, HP = High Pressure, B (LP = Low Pressure, HP = High Pressure, B
= Blind flange): = Blind flange):
Type of
Type of
compr.
compr.
NH3 NH3
1 1 1 1 1 1
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
0 1 2 0 1 2
L 9 L H
2 B
P 3 P P
L 1
3 H L
P 0 B
P P
2
L
4
P
Relief valves R134a
L
6
P Relief valve positions per cylinder number
(LP = Low Pressure, HP = High Pressure, B
L = Blind flange):
Type of
compr.
9 B
P R134a
1 L 1 1 1
B 1 2 3 4 5 6 7 8 9
2 P 0 1 2
2 L H L
1 P P 2
P
3 L H L
1 P P 3
P
4 L H L
2 P P 4
P
5 L H L
1 P P 6
P
6 L H L
3 P P 9 B
P
7 L H 1 L L
2 P P 2 P P
8 L H 2 L H
B B
4 P P 1 P P

Relief valves R134a Relief valves R404A
Relief valve positions per cylinder number Relief valve positions per cylinder number
(LP = Low Pressure, HP = High Pressure, B (LP = Low Pressure, HP = High Pressure, B
= Blind flange): = Blind flange):
Type of
Type of
compr.
compr.
R134a R404A
1 1 1 1 1 1
1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
0 1 2 0 1 2
3 L H L
2
1 P P P
4 L H L
3
2 P P P
5 L H L
4
1 P P P
6 L H L
6
3 P P P
7 L H L L
9
2 P P P P
8 L H H 1 L L
B
4 P P P 2 P P
9 L H 2 L H
B
3 P P 1 P P
1 3 L H
H L L
0 1 P P
P P P
2
4 L H
2 P P
5 L H
1 P P
6 L H
3 P P
7 L H
2 P P
8 L H L H
4 P P P P

Relief valves R404A
Relief valve positions per cylinder number

(LP = Low Pressure, HP = High Pressure, B
= Blind flange):
Type of
compr.
R404A
1 1 1
1 2 3 4 5 6 7 8 9
0 1 2
9 L H L
3 P P P
1
H L L
0
P P P
2

5.8 MOUNTING O-RINGS

Hint!
Warning! Pull the O-ring slightly and release it in

the groove, be sure that the O-ring IS
In order to avoid damaging O-rings NOT twisted (Figure 178, Page 78)
during re-assembling the compressor,
carefully read the following Warning!
instruction!
Never roll the O-ring in the groove
(Figure 179, Page 78) because the O-
ring will twist. This results into
leakage!
Fig.176: Clean the groove carefully with a clean, non fibrous

cloth
Fig.179: WRONG WAY OF MOUNTING
Fig.177: Oil the O-ring with compressor oil
Fig.178: Proper way of mounting


We live our values.
Excellence • Passion • Integrity • Responsibility • GEA-versity
GEA Group is a global engineering company with multi-billion euro sales and operations in more than
50 countries. Founded in 1881, the company is one of the largest providers of innovative equipment and
process technology. GEA Group is listed in the STOXX® Europe 600 Index.
© GEA Group AG. All rights reserved. Subject to modification
GEA Refrigeration Technologies

GEA Refrigeration Netherlands N.V.
Parallelweg 27, 5223 AL ‘s-Hertogenbosch, The Netherlands
Phone: +31 73 6203911
info@gea.com, www.gea.com

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Reciprocating Compressors for industrial refrigeration

Service Instruction Manual

2 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 3

4 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

GENERAL INFO SIM

Installation and maintenance intructions

Additional design details

How to read the pages of this manual

Important tables, refer to Chapter 5, Page 68!

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 5

6 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

Fig.2: Cylinder numbering Grasso reciprocating compressors

1, 2, 3, ... Cylinder numbers

T Top view of compressor

M Motor/Drive end of compressor

O Oil pump of compressor

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 7

8 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

Main setup data

Description Value Remark

Start frequency max. 6 starts per hour

Time interval between stopping and

Time interval between starting and

For continuous minimum part-load (i.e.

Oil level 25-75% crankcase sight glass

> 10 oC and > Pcrankcase +

Required oil viscosity;

Control oil pressure suction pressure + 8 bar

After a mimimum of 15 minutes running

Max. discharge temperature 170 °C

Min. suction pressure 0.3 bar

NH3 - 7.0 bar

Pdischarge - Psuction ≤17.5 bar

>0 Kfor NH3,

Oil suction filter Blue coloured filter element

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 9

Main setup data

Description Value Remark

Oil discharge - permanent - filter Grey filter element Supplied loose;

Direction of rotation of compressor Counterclockwise when facing

10 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 11

4.1.3 ASSEMBLY PROCEDURE 4, 6, 9 AND 12 CYLINDER COMPRESSORS 51

12 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

1 REPAIR AND OVERHAUL

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 13

4. Remove the refrigerant by means of a vacuum 8. Re-install the main fuses.

1.3.2 LEAK-TIGHTNESS AFTER 1.4 GENERAL RECOMMENDATIONS

14 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

7. Always replace damaged or worn compressor

GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016 15

2.1 REMOVING FLYWHEEL

5. Remove the four M12 hexagon head bolts.

1. Alternately unscrew the four M12-bolts five

7. Remove the locking disc.

2. Remove the locking plate.

16 GEA Refrigeration Netherlands N.V. | 0087123gbr_5 | Created 09.05.2016

1. Now slide the wheel or V-belt pulley hanging in

2.2 DISMANTLING SUCTION GAS