Component Operation: Section 3
Component Operation: Section 3
Component Operation: Section 3
COMPONENT OPERATION
CONTENTS
Group 1 Pump Device Group 4 Pilot Valve
Outline .....................................................T3-1-1 Outline .....................................................T3-4-1
Main Pump1 .............................................T3-1-2 Operation .................................................T3-4-2
Main Pump 2 and Pilot Pump....................T3-1-4
Group 5 Travel Device
Group 2 Swing Device Outline .....................................................T3-5-1
Outline .....................................................T3-2-1 Travel Motor .............................................T3-5-2
Swing Motor .............................................T3-2-2 Parking Brake...........................................T3-5-4
Parking Brake Switch Valve......................T3-2-4 Travel Brake Valve ...................................T3-5-6
Valve Unit.................................................T3-2-6 Travel Reduction Gear ...........................T3-5-10
Swing Reduction Gear............................T3-2-10
Group 6 Others (Upperstructure)
Group 3 Control Valve Pilot Shut-Off Valve ..................................T3-6-1
Outline .....................................................T3-3-1 Swing Mode Control Valve........................T3-6-2
Control Valve Layout ................................T3-3-2 Shockless Valve .......................................T3-6-4
Hydraulic Circuit .....................................T3-3-12 7-Spool Solenoid Valve Unit (EX75US-3) ..T3-6-8
Flow Combiner Valve .............................T3-3-20 Pilot Relief Valve ....................................T3-6-10
Main Relief Set Pressure Change...........T3-3-22 EC Motor ................................................T3-6-11
Boom Anti-Drift Valve (EX60-5) ...............T3-3-24
Main Relief Valve ...................................T3-3-26 Group 7 Others (Undercarriage)
Overload Relief Valve.............................T3-3-28 Swing Bearing ..........................................T3-7-1
Center Joint..............................................T3-7-2
Track Adjuster ..........................................T3-7-3
152T-3-1
(Blank)
152T-3-2
COMPONENT OPERATION / Pump Device
OUTLINE
The pump device is directly connected to the engine
and consists of main pump 1, main pump 2 (EX75UR-
3, 75URLC-3), and the pilot pump. The pump device
has a pump control solenoid valve to regulate main
pump 1 flow rate.
Main pump 1 is a variable displacement, swash plate
axial plunger type. The dual type delivery ports dis-
charge high pressure hydraulic oil to control valve 1.
Main pump 2 (EX75UR-3, 75URLC-3) is a gear pump
type discharging high pressure hydraulic oil to control
valve 2.
The pilot pump is a gear pump type discharging pres-
sure oil to the pilot circuit.
• EX60-5
Main Pump 1
Pilot Pump
• EX75UR-3, EX75URLC-3
Main Pump 2
Main Pump 1 Pilot Pump
T3-1-1
COMPONENT OPERATION / Pump Device
MAIN PUMP 1
The shaft is splined to the cylinder block in which In the cylinder block, the oil inlet and outlet ports are
plungers are located. arranged alternately along dual circle diameters. The
When the engine rotates, the shaft is rotated together valve plate has a set of dual outlet ports (one of each is
with the cylinder block and plungers. While sliding located inside and outside respectively.) and one inlet
along the shoe plate, the plungers reciprocate inside port. The dual outlet port design allows one pump to
the cylinder block. The plunger stroke varies depend- function like two pumps having equal oil displacement.
ing on the swash plate angle.
Valve Plate
Outlet Port (Inside)
Inlet Port
Inlet-Outlet Port
(Outside)
Inlet-Outlet Port
(Inside)
T5632-02-02-003
Cylinder Block
T3-1-2
COMPONENT OPERATION / Pump Device
Flow Rate Increase / Decrease Operation
• Flow Rate Control by Pump Delivery Pressure: • Flow Rate Decrease by Pilot Pressure:
The delivery pressure from main pump 1 is par- When the pump control solenoid valve is activated
tially routed to the oil chamber in each control pis- (ON), the pilot pressure is routed to the control
ton 2 on pump (pump is equipped with two control piston, reducing the swash plate angle, until the
pistons). control piston force balances with the spring force.
When the delivery pressure increases in the oil Thereby, the pump flow rate decreases.
chamber, control piston 3 is moved to the left side (Refer to SYSTEM/Control System in this man-
of the illustration by the oil pressure in the oil ual.)
chamber.
Then, the swash plate tilt angle is reduced until • Flow Rate Increase by Pilot Pressure:
the reaction force from the spring balances with When the pump control solenoid valve is deacti-
the oil pressure force via control piston 3, decreas- vated (OFF), the pilot pressure, which was acting
ing pump delivery flow rate. on the control piston, is returned to the hydraulic
oil tank. Then, the control piston is moved back-
ward by spring force, increasing the swash plate
angle. Thereby, the pump flow rate increases.
(Refer to SYSTEM/Control System in this man-
ual.)
NOTE: EX60-5 is illustrated here.
Oil
Chamber
Control Control Control Pump Control T152-03-01-002
Delivery
Pressure from
Pump 1
T3-1-3
COMPONENT OPERATION / Pump Device
MAIN PUMP 2 AND PILOT PUMP
Main pump 2 (EX75UR-3, EX75URLC-3) and the pilot
pump are connected to main pump 1 shaft by a cou-
pling. Therefore, main pump 2 and the pilot pump are
rotated together with main pump 1 when the engine
rotates.
When the drive gear rotates, the driven gear is rotated.
The hydraulic oil, routed from the inlet port, fills the
grooves between teeth on each gear, is transferred
along the inside surface of the housing, and dis-
charged from the outlet port.
• EX60-5 Main Pump 1
Pilot Pump
T152-03-01-001
• EX75UR-3, EX75URLC-3
Main Pump 1
Main Pump 2
Pilot Pump
T195-03-01-001
Inlet Port
Housing
Outlet Port
T137-02-005
T3-1-4
COMPONENT OPERTATION / Swing Device
OUTLINE
The swing device consists of the valve unit, the parking The swing motor is a swash-plate-type axial plunger
brake switch valve, the swing motor, and the swing reduc- motor incorporating the parking brake. The swing
tion gear. motor, driven by pressure oil from the pump, trans-
The valve unit prevents the occurrence of cavitation and mits the rotation force to the swing reduction gear.
overload in the swing circuit. The swing reduction gear converts the swing motor
The parking brake switch valve controls the brake release rotation power to a slow but large torque which ro-
oil pressure to engage or disengage the brake. tates the upperstructure.
The rotation speed is variable by in two stage de-
pending on whether normal mode or the precise
swing mode control is selected.
(EX75UR-3, EX75URLC-3) (Refer to SYSTEM / Con-
trol System in this manual.)
Valve Unit
Swing Motor
Parking Brake
Switch Valve
Swing
Swing Reduction
Reduction
Gear
Gear Parking Brake
Switch Valve
T152-03-02-001
T102-02-04-016
T3-2-1
COMPONENT OPERTATION / Swing Device
SWING MOTOR
• EX60-5
The shaft and the rotor constitutes one unit. In the rotor
section, plungers are installed. When the pump supplies
pressure oil to the swing motor, plungers are pushed down
with pressure oil while sliding along the swash plate, devel-
oping turning force. As the shaft tip end is splined to the first
stage sun gear in the swing reduction gear, the rotor torque
is transmitted to the swing reduction gear unit.
Brake Piston
Friction Plate
Brake Piston
Chamber
Plate
Shoe
Rotor
Swash Plate
Plunger
T152-03-02-002
T3-2-2
COMPONENT OPERTATION / Swing Device
• EX75UR-3, EX75URLC-3
The shaft is splined to the rotor in which plungers are
installed.
When the pump supplies pressure oil to the swing mo-
tor, the plungers are pushed down with pressure oil
while sliding along the swash plate, developing rotor
turning force.
The shaft tip end is splined into the first stage sun gear
in the swing reduction gear so that shaft rotation is
transmitted to the swing reduction gear.
Rotor
Plunger
Shoe
Swash Plate
Shaft
T102-02-04-001
T3-2-3
COMPONENT OPERTATION / Swing Device
PARKING BRAKE SWITCH VALVE
The parking brake is a wet-negative-type multiple disc
brake which is released only when the brake release
pressure oil is routed into the brake piston chamber.
Therefore, the parking brake is released when the
swing or the front attachment function is operated.
While traveling or when the engine is stopped, the
brake is applied by spring force.
• EX60-5:
When releasing the brake: When the brake is applied:
When the swing or front attachment control lever is When the swing or the front attachment control lever
operated, the brake release signal pressure is guided is returned to neutral, the brake release signal pres-
to port SH from the control valve. Then, the brake re- sure is not guided to port SH so that the spool is
lease signal pressure is routed through the orifice to moved upward.
move the spool downward. At this time, the brake release pressure oil existing
On the other hand, the pilot pressure is always fed to under the spool flows back via the orifice, causing the
port PG while the engine is running. Therefore, when spool to gradually close port PG and the brake re-
the spool is moved downward and the oil port to the lease port.
brake piston chamber is connected to port PG, the Accordingly, the brake piston gradually moves down-
pilot pressure is guided to the brake piston chamber ward, allowing the plates to slowly come in contact with
via the brake release port. the friction plates enabling the swing movement to stop
Thereby, the brake piston is pushed upward, allowing smoothly.
the plate and the friction plate contact to free and re-
leasing the brake.
Spring
Port SH
Orifice (Brake Release
Signal Pressure)
Brake Piston
Chamber Spool
Brake Piston
Port PG
To brake (Brake Release
Plate piston Pressure)
chamber
Friction Plate
Brake
Release
Port
T152-03-02-007
Parking Brake
T152-03-02-003
T3-2-4
COMPONENT OPERTATION / Swing Device
• EX75UR-3, EX75URLC-3
When releasing the brake: When the brake is applied:
When the swing and/or front function is operated, the When the swing and/or the front function control lever
brake release signal pressure pushes the spool is returned to neutral, the brake release signal pres-
downward, allowing the brake release pressure oil to sure is not guided to the spool end, allowing the spool
flow into the brake piston chamber to move the brake to move upward and blocking the brake release pres-
piston up against spring force. Then, the plate and sure oil flow into the brake piston chamber. As the
the friction plate contact is freed releasing the brake. spool moves up, the oil passage in the spool con-
nects the brake piston chamber to the drain port so
that pressure oil in the brake piston chamber flows to
the drain port via the orifice. The oil flow is restricted
at the orifice, causing the brake piston to slowly push
the plates and friction plates, enabling the brake to be
applied gradually resulting in a smooth stop.
Brake Release
Signal Pressure
Port SH
Spring
Spool
Brake Piston
Chamber
Plate
Friction Plate
Orifice
Drain Port
T102-02-04-013
T3-2-5
COMPONENT OPERTATION / Swing Device
VALVE UNIT
The valve unit consists of the make-up valves and relief
valves.
The make-up valve prevents the occurrence of cavitation in
the circuit. The make-up valve also protects the circuit from
surge pressure and overloading.
Make-Up Valve
When the upperstructure is swing downward on a slope,
the upperstructure is accelerated by its own weight and
moves quicker than the swing motor drive speed devel-
oped by the pump oil flow rate. Therefore, cavitation can
occur in the circuit.
To prevent cavitation, when the oil pressure in the circuit
is lower than the pressure at port M (hydraulic oil tank
pressure), the poppet opens drawing hydraulic oil into the
circuit so that the pump oil flow rate is replenished.
• EX60-5:
Control Valve
Poppet Port M
Make-Up
Valve
T152-03-02-004
Relief Valve
T3-2-6
COMPONENT OPERTATION / Swing Device
• EX75UR-3, EX75URLC-3
Control Valve
Relief Valve
Relief Valve
Make-Up Valve
Make-Up Valve
Port M Poppet
T190-02-04-001
T3-2-7
COMPONENT OPERTATION / Swing Device
Relief Valve
The relief valve functions to reduce shocks developed
when starting or stopping swing movement (shockless)
and to protect the circuit from overloading (relief).
• EX60-5:
Shockless Operation:
When the circuit pressure increases, pressure oil is routed
into the piston chamber via the oil passage inside the pis-
ton and moves the piston to the left. As long as the piston
is moving, the spring set force is weak, allowing the pop-
pet to open. Then, hydraulic oil is relieved to the hydraulic
oil tank.
When the piston is moved to the stroke end, the spring set
force maintains the poppet at the regular relief pressure.
Relief Operation:
During swing operation, if the circuit pressure is increased
due to an external load higher than the relief set pressure,
the pressure higher than relief set pressure acts on the
poppet so that the poppet opens allowing the hydraulic oil
to be relieved.
Sleeve
Port M
(Hydraulic Oil Tank)
Swing Circuit
Piston Chamber
T152-03-02-005
Poppet Spring Piston
T3-2-8
COMPONENT OPERTATION / Swing Device
• EX75UR-5, EX75URLC-5:
• Shockless Function • Relief Function
When the pressure in the swing circuit A in- When the pressure in the swing circuit A in-
creases, it is routed into the piston chamber creases further, the pressure oil moves the shock-
through the orifice. less piston to the stroke end. Therefore, the pres-
Then, it is further routed behind the shockless pis- sure difference between the front and rear of the
ton via holes on the cartridge so that the shock- poppet disappears and the pressure increases up
less piston is moved to the right. As long as the to the relief set pressure.
shockless piston is moving, the pressure in the If the pressure in the swing circuit A is increased
piston chamber is maintained at low pressure. by an external load, the poppet is unseated
Therefore, the pressure difference arises between against spring force, allowing the hydraulic oil to
the front and the rear of the poppet. When the relieve.
pressure difference increases more than spring
force, the poppet is unseated, relieving the pres- • Quick Return of Shockless Piston
sure oil to the hydraulic oil tank. When the swing lever is moved in reverse, high oil
When the shockless piston moves to position Y on pressure acts on the chamfer at the right end face
the piston guide, the shockless piston stops. corner of the piston guide. Then, the piston guide
Therefore, the pressure difference between the is moved to the left due to the pressure difference
front and the rear of the poppet disappears, caus- between both ends of the piston guide. Therefore
ing the poppet to re-seat. the shockless piston is moved along with the pis-
ton guide to the left original position, by which
shockless function is quickly resumed.
Piston Chamber
Spring Cartridge Port M Orifice
Swing Circuit (Hydraulic Oil Tank)
B
Swing Circuit A
Piston Guide
Piston Guide
Shockless Y Stroke End
Piston
T554-02-04-005
T3-2-9
COMPONENT OPERTATION / Swing Device
SWING REDUCTION GEAR
The swing reduction gear is a two-stage planetary gear
type.
The swing motor drives the first stage sun gear via the shaft.
Then, the first stage sun gear rotary speed is reduced be-
tween the first stage planetary gear and the first stage car-
rier and transmitted to the second stage sun gear. The
second stage sun gear drives the shaft after the rotary
speed of the second stage sun gear is reduced between
the second stage planetary gear and the second stage car-
rier.
• EX60-5: • EX75UR-3, EX75URLC-3:
First Stage
First stage Sun Gear
Planetary Gear
First stage
Planetary Gear
First Stage
Carrier
Second Stage
Carrier
Shaft
T102-02-04-016
T152-03-02-006
T3-2-10
COMPONENT OPERATION / Control Valve
OUTLINE
The control valve controls oil pressure, flow rate, and Spool Arrangement in Control Valve 1 (Viewed from
flow direction in the hydraulic circuit. the right side):
The major components are main relief valve, overload In 4-Spool Section: Right Travel, Bucket, Boom 1, and
relief valves, flow combiner valve, boom anti-drift valve Arm 2
(EX60-5), relief set pressure change valve (EX75UR-3, In 5-Spool Section: Left Travel, offset (EX60-5,
EX75URLC-3), and spools. The travel control spool are EX75URLC-3: Auxiliary), Boom 2, Arm 1, and Swing.
manually operated. The front attachment and swing Spool Arrangement in Control Valve 2 (EX75UR-3,
spools are operated by pilot pressure. EX75URLC-3) (Viewed from the front side):
Swing (Precise Swing Mode), and Blade.
Right Travel
Control Valve 1 (located on Bucket Left Travel (located
• EX60-5 the right side • EX75UR-3, EX75URLC-3 on the right side of
of the aux.) Boom 1
the offset)
Boom 2 Offset
Arm 2
Arm 1
Machine Front
Swing
Machine Front
Left Travel
Right Travel
Bucket
Auxiliary Boom 1
Arm 2
Boom 2
T192-03-03-001
Arm 1
Swing
• EX75UR-3, EX75URLC-3 (Control Valve 2)
Machine Front
T152-03-03-016
T3-3-1
COMPONENT OPERATION / Control Valve
CONTROL VALVE LAYOUT
EX60-5: 1 2 3 4 5 6
22
7
21 8
20
Bucket
Cylinder
9
19 10
11
Arm Boom
Cylinder Cylinder
18
17
12
13
Swing Motor
Control Valve
16 15 14
1 - Main Relief Valve 7 - Load Check Valve 13 - Load Check Valve 19 - Overload Relief Valve
(Bucket Circuit) (Arm 1 Circuit) (Arm Circuit)
2 - Check Valve 8 - Overload Relief Valve 14 - Check Valve (Arm Roll-In 20 - Check Valve
(Bucket) Flow Combining Circuit) (Auxiliary Parallel Circuit)
3 - Check Valve 9 - Load Check Valve 15 - Check Valve (Arm Roll-Out 21 - Check Valve (Travel Left
(Boom 2 Circuit) Flow Combining Circuit) Parallel Circuit)
4 - Check Valve (Bucket Flow 10 - Boom Anti-Drift Valve 16 - Check Valve 22 - Load Check Valve
Combining Circuit) (Check Valve) (Swing Parallel Circuit) (Travel Left Circuit)
5 - Flow Combiner Valve 11 - Boom Anti-Drift Valve 17 - Load Check Valve
(Switch Valve) (Arm 2 Tandem Circuit)
6 - Check Valve 12 - Overload Relief Valve 18 - Check Valve
(Boom Circuit) (Arm 2 Parallel Circuit)
T3-3-2
COMPONENT OPERATION / Control Valve
Section A
G 1
B
A
T152-05-04-004
2 3
View
T152-03-03-003
Section B
Section C
6 5
21, 22
T152-03-03-004
T152-03-03-005
T3-3-3
COMPONENT OPERATION / Control Valve
EX60-5: 1 2 3 4 5 6
22
7
21 8
20
Bucket
Cylinder
9
19 10
11
Arm Boom
Cylinder Cylinder
18
17
12
13
Swing Motor
Control Valve
16 15 14
1 - Main Relief Valve 7 - Load Check Valve 13 - Load Check Valve 19 - Overload Relief Valve
(Bucket Circuit) (Arm 1 Circuit) (Arm Circuit)
2 - Check Valve 8 - Overload Relief Valve 14 - Check Valve (Arm Roll-In 20 - Check Valve
(Bucket) Flow Combining Circuit) (Auxiliary Parallel Circuit)
3 - Check Valve 9 - Load Check Valve 15 - Check Valve (Arm Roll-Out 21 - Check Valve (Travel Left
(Boom 2 Circuit) Flow Combining Circuit) Parallel Circuit)
4 - Check Valve (Bucket Flow 10 - Boom Anti-Drift Valve 16 - Check Valve 22 - Load Check Valve
Combining Circuit) (Check Valve) (Swing Parallel Circuit) (Travel Left Circuit)
5 - Flow Combiner Valve 11 - Boom Anti-Drift Valve 17 - Load Check Valve
(Switch Valve) (Arm 2 Tandem Circuit)
6 - Check Valve 12 - Overload Relief Valve 18 - Check Valve
(Boom Circuit) (Arm 2 Parallel Circuit)
T3-3-4
COMPONENT OPERATION / Control Valve
Section D Section E
10
8
11
20
9
12
T152-03-03-007 T152-03-03-006
8
Section F Section G
12 19
14
17, 18 16
13
15
19
T152-03-03-009
T152-03-03-008
T3-3-5
COMPONENT OPERATION / Control Valve
EX75UR-3, EX75URLC-3
Control Valve 1
1 2 3 4 5 6 7
25 26 27
10
24
23 11
12
22
28 13
21
14
20
18 17 16
19 15
T192-03-03-003
1 - Main Relief Valve 8 - Load Check Valve 15 - Check Valve 22 - Load Check Valve
(Front Attachment/Swing) (Travel Parallel Circuit) (EX60-5, 75UR-3: Offset
Parallel Circuit)
(EX75URLC-3: Auxiliary
Tandem Circuit)
2 - Main Relief Valve (Travel) 9 - Check Valve 16 - Check Valve 23 - Overload Relief Valve
(Flow Combining Circuit) (EX60-5, 75UR-3 Offset)
(EX75URLC-3: Auxiliary )
3 - Relief Set Pressure 10 - Load Check Valve 17 - Check Valve 24 - Load Check Valve
Change Valve (Bucket Circuit) (Travel Tandem Passage)
4 - Check Valve 11 - Overload Relief Valve 18 - Load Check Valve 25 - Main Relief Valve
(Bucket) (Arm 1 Parallel Circuit) (Precise Swing)
5 - Check Valve 12 - Load Check Valve (Boom 1 19 - Load Check Valve 26 - Load Check Valve
Parallel Circuit) (Swing Parallel Circuit) (Swing Circuit)
6 - Flow Combiner Valve 13 - Overload Relief Valve 20 - Load Check Valve 27 - Load Check Valve
(Boom) (Arm 1 Tandem Circuit) (EX60-5, 75UR-3: Blade
Parallel Circuit)
(EX75URLC-3: Auxiliary )
7 - Check Valve 14 - Load Check Valve 21 - Overload Relief Valve 28 - Overload Relief Valve
(Arm 2 Tandem Circuit) (Arm) (EX60-5, 75UR-3: Blade)
(EX75URLC-3: Auxiliary )
T3-3-6
COMPONENT OPERATION / Control Valve
Control Valve 1
Section A
2 1
F
C
3
T195-03-03-015
4 5
View
7
6 T195-03-03-002
Section C
Section B
23 11
8, 24
22 10
23
11
T195-03-03-003
T195-03-03-004
T3-3-7
COMPONENT OPERATION / Control Valve
EX75UR-3, 75URLC-3
Control Valve 1
1 2 3 4 5 6 7
25 26 27
10
24
23 11
12
22
28 13
21
14
20
18 17 16
19 15
T192-03-03-003
1 - Main Relief Valve 8 - Load Check Valve 15 - Check Valve 22 - Load Check Valve
(Front Attachment/Swing) (Travel Parallel Circuit) (EX60-5, 75UR-3: Offset
Parallel Circuit)
(EX75URLC-3: Auxiliary
Tandem Circuit)
2 - Main Relief Valve (Travel) 9 - Check Valve 16 - Check Valve 23 - Overload Relief Valve
(Flow Combining Circuit) (EX60-5, 75UR-3 Offset)
(EX75URLC-3: Auxiliary )
3 - Relief Set Pressure 10 - Load Check Valve 17 - Check Valve 24 - Load Check Valve
Change Valve (Bucket Circuit) (Travel Tandem Passage)
4 - Check Valve 11 - Overload Relief Valve 18 - Load Check Valve 25 - Main Relief Valve
(Bucket) (Arm 1 Parallel Circuit) (Precise Swing)
5 - Check Valve 12 - Load Check Valve (Boom 1 19 - Load Check Valve 26 - Load Check Valve
Parallel Circuit) (Swing Parallel Circuit) (Swing Circuit)
6 - Flow Combiner Valve 13 - Overload Relief Valve 20 - Load Check Valve 27 - Load Check Valve
(Boom) (Arm 1 Tandem Circuit) (EX60-5, 75UR-3: Blade
Parallel Circuit)
(EX75URLC-3: Auxiliary )
7 - Check Valve 14 - Load Check Valve 21 - Overload Relief Valve 28 - Overload Relief Valve
(Arm 2 Tandem Circuit) (Arm) (EX60-5, 75UR-3: Blade)
(EX75URLC-3: Auxiliary )
T3-3-8
COMPONENT OPERATION / Control Valve
Section D Section E
13 21
17
15
18, 20
12
14
16
13 21
T195-03-03-006
T195-03-03-005
Section F
5 4
19
T195-03-03-008
W102-02-05-016
T3-3-9
COMPONENT OPERATION / Control Valve
EX75UR-3, 75URLC-3
Control Valve 2
1 2 3 4 5 6 7
25 26 27
10
24
23 11
12
22
28 13
21
14
20
18 17 16
19 15
T192-03-03-003
1 - Main Relief Valve 8 - Load Check Valve 15 - Check Valve 22 - Load Check Valve
(Front Attachment/Swing) (Travel Parallel Circuit) (EX60-5, 75UR-3: Offset
Parallel Circuit)
(EX75URLC-3: Auxiliary
Tandem Circuit)
2 - Main Relief Valve (Travel) 9 - Check Valve 16 - Check Valve 23 - Overload Relief Valve
(Flow Combining Circuit) (EX60-5, 75UR-3 Offset)
(EX75URLC-3: Auxiliary )
3 - Relief Set Pressure 10 - Load Check Valve 17 - Check Valve 24 - Load Check Valve
Change Valve (Bucket Circuit) (Travel Tandem Passage)
4 - Check Valve 11 - Overload Relief Valve 18 - Load Check Valve 25 - Main Relief Valve
(Bucket) (Arm 1 Parallel Circuit) (Precise Swing)
5 - Check Valve 12 - Load Check Valve (Boom 1 19 - Load Check Valve 26 - Load Check Valve
Parallel Circuit) (Swing Parallel Circuit) (Swing Circuit)
6 - Flow Combiner Valve 13 - Overload Relief Valve 20 - Load Check Valve 27 - Load Check Valve
(Boom) (Arm 1 Tandem Circuit) (EX60-5, 75UR-3: Blade
Parallel Circuit)
(EX75URLC-3: Auxiliary )
7 - Check Valve 14 - Load Check Valve 21 - Overload Relief Valve 28 - Overload Relief Valve
(Arm 2 Tandem Circuit) (Arm) (EX60-5, 75UR-3: Blade)
(EX75URLC-3: Auxiliary )
T3-3-10
COMPONENT OPERATION / Control Valve
Control Valve 2
25
T192-03-03-005
28
26, 27
T192-03-03-006
T3-3-11
COMPONENT OPERATION / Control Valve
HYDRAULIC CIRCUIT
The control valve hydraulic circuit falls into 3 main groups:
main circuit, pilot pressure operation circuit, and signal pilot
pressure circuit.
• EX60-5:
Main Circuit
The main pump 1 pressure oil from the rear port is routed
to the 4-spool section and from the front port to the 5-
spool section, respectively.
When the spool (control lever) is in the neutral position,
the pressure oil from the main pump 1 flows through the
neutral passage and returns to the hydraulic oil tank.
When the spool (control lever) is operated, the pressure
oil from the main pump flows through the spool to the ac-
tuator.
The main circuit has the parallel circuits and flow combin-
ing circuits, making actuator combined operations possi-
ble.
The main circuit pressure (between the pumps and the ac-
tuators) is regulated by the main relief valve so that the
main circuit pressure is maintained within the set pressure
during operation. The main relief valve set pressure varies
in two stages depending on whether travel function is op-
erated or the front attachment and/or swing function is
operated.
The actuator circuit pressure (between the control valve
and the actuators) is regulated by the overload relief
valves, protecting the circuit from surge pressure devel-
oped by external loads.
T3-3-12
COMPONENT OPERATION / Control Valve
(4-Spool Section)
Main Relief
Valve
Right
Left Travel
Travel
Neutral Circuit
Flow Combining
Circuit
Boom 2 Boom 1 Overload
Overload Relief Valve
Relief Valve
Arm Boom
Cylinder Cylinder
Arm 1 Arm 2
Swing Motor
Swing Neutral
Circuit
Parallel
Circuit
T3-3-13
COMPONENT OPERATION / Control Valve
• EX75UR-3 and EX75URLC-3
Main Circuit
Pressurized oil from main pump 1 (rear) is routed to
the 4-spool section in control valve 1, pressurized oil
from main pump 1 (front) is routed to the 5-spool sec-
tion in control valve 1, and pressurized oil from main
pump 2 is routed to control valve 2.
When the spools are in neutral (when the control lev-
ers are in neutral), pressurized oil from the pumps re-
turns to the hydraulic oil tank through the neutral pas-
sages.
When the spool is shifted (when the control lever is
moved), pressurized oil from the pumps flows into the
actuators via the spools. The man circuit includes the
parallel circuit and flow combining circuit. They en-
able combined operations by actuator.
The oil pressure in the main circuit (between the
pump and the control valve) is controlled by the main
relief valve so that the oil pressure does not exceed
the set pressure during operation. Control valve 1 is
equipped with two relief valves, for the front attach-
ment and the swing circuits. By selecting the actua-
tors the relief pressures setting varies.
The overload relief valve controls the oil pressure in
the actuator circuits (between the control valve and
the actuators), preventing surge pressure due to the
external forces so that the pressure in the actuator is
maintained below the desired pressure.
T3-3-14
COMPONENT OPERATION / Control Valve
Blade
Cylinder
Offset
Cylinder Bucket
Cylinder
Parallel
Passage
Swing
Motor Parallel
Passage
(5-Spool (4-Spool
Main Circuit
Section) Section)
Control Valve 1
Front Rear
T3-3-15
COMPONENT OPERATION / Control Valve
• EX60-5:
Pilot Pressure Operation Circuit
The control valve spools in this circuit are controlled by
pressure oil from the pilot valve. In this circuit, the air vent
circuit is provided so that trapped air in the circuit is auto-
matically bled.
T3-3-16
COMPONENT OPERATION / Control Valve
Main Relief
Valve
Flow
Combiner Signal Pilot Pressure
Valve Circuit (Travel)
Control Valve
Air Vent Circuit
T152-03-03-017
T3-3-17
COMPONENT OPERATION / Control Valve
• EX75UR-3 and EX75URLC-3
Pilot Circuit
The spools in the control valves are actuated by the
oil pressure (shown with key numbers) from the pilot
valves. The air bleeder circuits are provided to auto-
matically discharge air trapped in the circuit.
T3-3-18
COMPONENT OPERATION / Control Valve
Pressure Flow
Relief Pressure Switch Combiner
Change Valve (Travel) Valve
7
5
1
Signal Pilot
Pressure Cir-
4 cuit
3 (Travel)
6 Signal Pilot
5 Pressure
Circuit
(Front
Attachment
Air Bleeder Circuit and Swing)
Pilot Pump
T192-03-03-008
1 - Boom Lower 3 - Arm Roll-In 5 - Left Swing 7 - Bucket Roll-In
2 - Boom Raise 4 - Arm Roll-Out 6 - Right Swing 8 - Bucket Roll-Out
T3-3-19
COMPONENT OPERATION / Control Valve
FLOW COMBINER VALVE
When the front attachment and/or swing function is oper- The main pump 1 pressure oil from the front port is
ated, the corresponding spool restricts the signal pilot pres- routed to the front attachment and/or swing spool.
sure oil flow in the front attachment and/or swing system, Accordingly, the pressure oil to the right and left
increasing signal pilot oil pressure. Thereby, the flow com- travel motors is fed from the rear port main pump 1
biner valve is operated. and the pressure oil to the front attachment and/or
At this time, when the travel function is operated, the main swing function is fed from the front port main pump 1.
pump pressure oil from the rear port is routed to the right Therefore, when the combined operation of traveling
travel spool as well as the left travel spool via the flow com- with front attachment and/or swing is conducted, the
biner valve. both side travel motors are fed with an equal amount
of pressure oil, ensuring straight traveling.
Right
Left Travel
Travel
Bucket Bucket
Cylinder
Boom 2 Boom 1
Arm Boom
Cylinder Cylinder
Arm 1 Arm 2
Swing Motor
Swing
Control Valve
T3-3-20
COMPONENT OPERATION / Control Valve
• EX75UR-3 and EX75URLC-3 Left Travel Motor
Signal Pilot Right Travel Motor
Pressure
Circuit for
Flow Combiner Valve Front
Attachment
and Swing
Left Travel
Right
Travel
Arm 1
Arm 2
Main Pump 1
T192-02-03-004
T3-3-21
COMPONENT OPERATION / Control Valve
MAIN RELIEF SET PRESSURE CHANGE
• EX60-5:
When the travel function is operated, the signal pilot
pressure in the travel circuit is restricted by the travel
spool, increasing the signal pilot pressure. Therefore,
the increased pilot pressure is guided to the spring
side of the main relief valve, causing the relief set
pressure to increase.
Travel Signal
Pilot Pressure Circuit
Left Travel
Right
Travel
T152-03-03-012
T3-3-22
COMPONENT OPERATION / Control Valve
• EX75UR-3,EX75URLC-3:
When the travel function is operated, the signal pilot oil flow NOTE: EX75UR-3 is illustrated here.
is restricted by the travel spool, increasing the pilot oil pres-
sure so that the relief pressure change valve is activated.
Accordingly, the travel main relief valve is connected to the
main circuit via the relief pressure change valve. The travel
main relief valve set pressure is lower than the front at-
tachment and swing main relief valve. Therefore the pres-
sure in the main circuit is controlled by the travel main relief
valve at this time.
When only the front attachment and/or swing function is
operated, the relief pressure change valve is not activated
so that the relief pressure in the main circuit is controlled by
the front attachment and swing main relief valve set pres-
sure.
Left Travel
Pilot Pump
T192-03-03-009
T3-3-23
COMPONENT OPERATION / Control Valve
BOOM ANTI-DRIFT VALVE (EX60-5)
The boom anti-drift valve is provided on the boom cyl-
inder bottom side circuit to reduce the boom cylinder
drift.
T3-3-24
COMPONENT OPERATION / Control Valve
Hydraulic Oil
Spool
Piston
Boom Lower
Pilot Pressure
Spring
Boom Cylinder
Check Valve
To boom spool
To boom spool
T152-03-03-013
T3-3-25
COMPONENT OPERATION / Control Valve
MAIN RELIEF VALVE
The main relief valve prevents the main circuit pres-
sure from rising higher than the set pressure. The relief
set pressure varies depending on whether travel or
front attachment and/or swing function is oper-
ated.(Refer to T3-3-22, 23.)
• EX60-5:
When front attachment and/or swing function is
operated (low relief set pressure):
When pressure at port Hp reaches the set spring
force, the pilot poppet opens, allowing pressure oil to
flow to port Lp via passage A.
At this time, as the orifice is provided, a pressure dif-
ference is present between port Hp (higher) and
spring chamber A (lower). If this pressure difference
becomes larger than spring A force, the main poppet
opens, allowing pressure oil to flow from port Hp to
port Lp.
Main Pilot
Orifice Poppet Poppet Piston
Hp Port SG
Lp
T152-03-03-014
T3-3-26
COMPONENT OPERATION / Control Valve
• EX75UR-3, EX75URLC-3:
Main Relief Valve in Control Valve 1
When the pressure at port Hp increases higher than the
spring B set force, the pilot poppet is unseated. When the
pilot poppet is unseated, the pressure oil is routed to port
Lp through the grooves around the sleeve. Then, the
pressure in spring chamber A decreases, allowing the
main poppet to open. Therefore, the pressure oil at port
Hp is relieved to port Lp.
Hp
Lp
Spring Chamber A
T132-02-05-001
Hp
Lp
T190-02-05-006
T3-3-27
COMPONENT OPERATION / Control Valve
OVERLOAD RELIEF VALVE
NOTE: The construction of the overload relief
The overload relief valve prevents the pressure in the
valves in control valves 1 and 2 (EX75UR-3,
actuator circuit from rising higher than the set pres-
EX75URLC-3) is identical.
sure.
When pressure at port Hp reaches the set spring force,
the pilot poppet opens, allowing the pressure oil to flow
to port Lp around the outer diameter of the sleeve.
At this time, as the orifice is provided, a pressure dif-
ference is present between port Hp (higher) and spring
chamber A (lower).If this pressure difference becomes
larger than spring A force, the main poppet opens, al-
lowing pressure oil to flow from port Hp to port Lp.
If the pressure at port Hp is lower than port Lp, the
sleeve opens. Thereby, oil is replenished from port Lp
to port Hp, preventing the occurrence of cavitation
(make-up operation).
• EX60-5:
Main Pilot
Orifice Poppet Sleeve Poppet
Hp
Lp
T152-03-03-015
Spring A Spring B
• EX75UR-3, EX75URLC-3:
Main Poppet Sleeve Pilot Poppet Spring B
Hp
Lp
T3-3-28
COMPONENT OPERATION / Pilot Valve
OUTLINE
The pilot valve controls pilot pressure to move the
control valve spools.
The standard 4-port type is used for the front
attachment and swing operation. An optional 2-port
type is used for the offset operation.
As for EX75UR-3, the standard 2-port type is used for
the offset operation.
All pilot valves have the same construction of the
pressure reducing valves except the cam by which the
pushers are moved.
2 Boom Lower
3 Bucket Roll-In ←
4 Boom Lower ←
1 Arm Roll-In Right Swing
2 Right Swing Arm Roll-Out
Left
P T
1 3 2 4
T105-02-07-020
T105-02-07-020
P T
1 2 T
T1554-02-07-009 P
1 2 T190-02-06-005
T3-4-1
COMPONENT OPERATION / Pilot Valve
OPERATION
Front and Swing Pilot Valve
The lower face of spool (8) head is suspended by the • In neutral
upper face of spacer (4); they are kept in contact by (Corresponding to A to B in the output diagram) :
setting force of balance spring (6). Spacer (4) is
installed between pusher (3) and spring guide (5) and When control lever (1) is in the neutral position (no
supported by return spring (7). Piston (9) is located pusher stroke), spool (8) completely blocks pressure
inside spool (8). The lower end of piston (9) makes oil from entering port P. Since the delivery port is
contact with the plate, preventing the piston from open to port T, pressure at the delivery port equals
moving further downward. that in the hydraulic oil tank.
Above piston (9), a chamber is provided and it is led to When control lever (1) is slightly moved, cam (2)
the outside of spool (8) through holes provided in spool moves together, pressing down on pusher (3).
(8). Then, pusher (3), spacer (4), and spring guide (5)
move downward as a unit, compressing return
spring (7).
The lower face of spool (8) is kept in contact with the
upper face of spacer (4) by setting force of balance
spring (6) and moves downward together with
spacer (4).
However, even if control lever (1) is moved further,
until clearance (A) at section (a) reaches zero, the
delivery port remains open to port T, keeping
pressure at the delivery port equal to that in the
hydraulic oil tank.
Delivery Port
Pressure
(Pilot Pressure)
Pusher Stroke
OUTPUT DIAGRAM
Section (a)
Port T
Delivery Port
Port P
T158-03-04-001
T3-4-2
COMPONENT OPERATION / Pilot Valve
• Ready to start operation
(Corresponding to B to C section in the output diagram) :
Delivery Port
Pressure
(Pilot Pressure)
Pusher Stroke
OUTPUT DIAGRAM
Section (a)
Delivery Port
Section (b)
Port P
T110-02-07-003
1 - Control Lever 6 - Balance Spring 9 - Piston 10 - Orifice
3 - Pusher 8- Spool
T3-4-3
COMPONENT OPERATION / Pilot Valve
• Operation corresponding to the control lever stroke
(Corresponding to C to D in the output diagram) :
As control lever (1) is moved further to push pusher (3) Accordingly, when compressed by pusher (3), spring
downward, spool (8) is pushed down to open the notch at force of balance spring (6) increases in proportion to
section (b), increasing oil pressure at the delivery port. the pusher stroke, Then, oil pressure increases to
As pressure increases, the force to push up spool (8) counteract against this spring force.
increases. Then, when force to push up spool (8)
exceeds the setting force of balance spring (6), spool (8)
starts to move upward, compressing balance spring (6).
When spool (8) moves upward until the clearance at
section (a) opens, the delivery port is opened to port T,
stopping oil pressure increase at the delivery port and
stopping movement of spool (8).
Delivery Port
Pressure
(Pilot Pressure)
Pusher Stroke
OUTPUT DIAGRAM
Section (a)
Port T
Delivery Port
Section (b)
Port P
T110-02-07-004
T3-4-4
COMPONENT OPERATION / Pilot Valve
• Operation close to pusher stroke end
(Corresponding to D to E in the output diagram) :
As pusher (3) is pressed down, balance spring (6) is Then, oil pressure at the delivery port increases
compressed, reducing clearance (B) between pusher (3) until it reaches port P pressure, by which the
and the top of spool (8) (shown at section (c) ), finally to operator feels that the control; lever is being
zero. operated close to the stroke end.
After that, pusher (3) directly pushes spool (8).
Even if oil pressure at the delivery port increases, spool
(8) cannot move upward, closing the oil passage from the
delivery port to port T, and opening the oil passage from
the delivery port to port P.
Delivery Port
Pressure
(Pilot Pressure)
Pusher Stroke
OUTPUT DIAGRAM
Section (c)
Port T
Delivery Port
Port P
T110-02-07-005
T3-4-5
COMPONENT OPERATION / Pilot Valve
• Full stroke operation
(Corresponding to E to F section in the output diagram) :
Delivery Port
Pressure
(Pilot Pressure)
Pusher Stroke
OUTPUT DIAGRAM
Section (d)
Port T
Delivery Port
Section (b)
Port P
T110-02-07-006
T3-4-6
COMPONENT OPERATION / Pilot Valve
(Blank)
T3-4-7
COMPONENT OPERATION / Pilot Valve
Offset Control Pilot Valve
A B
OUTPUT DIAGRAM
T523-02-05-001
T3-4-8
COMPONENT OPERATION / Pilot Valve
Pusher Stroke: A to B
1
Port T
(Clearance A:0)
(A)
Port P
6
2
2
4 (C)
Port T Port T 3
(B)
(A)
6 Port P
Port P
6
T191-03-04-010
Delivery Port T191-03-04-009 Delivery Port
T3-4-9
COMPONENT OPERATION / Pilot Valve
(Blank)
T3-4-10
COMPONENT OPERATION / Travel Device
OUTLINE
The travel device consists of the travel motor, travel
reduction gear, and travel brake valve.
On EX60-5 and EX75URLC-3, the travel motor is a
swashplate type fixed displacement axial plunger type.
On the EX75UR-3, the travel motor is a radial plunger
type. Both travel motors are driven by hydraulic oil
from the hydraulic pump and transmit rotating power to
the travel reduction gear. The travel reduction gear is a
two-stage planetary reduction gear which converts the
rotating power from the travel motor to a large slow-
speed torque to rotate the sprocket. The sprocket
drives the track link. The travel brake valve protects
the travel hydraulic circuit from overloading.
Sprocket Sprocket
Travel Brake
Valve
T152-03-05-001
T192-03-05-001
T152-03-05-001
T3-5-1
COMPONENT OPERATION / Travel Device
TRAVEL MOTOR
• EX60-5, EX75URLC-3:
The travel motor consists of the valve plate, rotor,
plungers, shoes, swash-plate, and shaft. The shaft is
connected with the rotor by a spline joint. The plungers
are installed in the rotor.
When pressure oil is supplied from the pump, the
plunger is pushed toward the swash-plate. The swash-
plate is installed at an angle toward the plungers. Then
the shoes slide along the swash-plate surface, causing
the rotor to rotate. This rotation is transferred to the
travel reduction gear via the shaft.
Shaft Swash-Plate
T152-03-05-002
T3-5-2
COMPONENT OPERATION / Travel Device
• EX75UR-3:
The coupling is connected to the rotor via the joint. The
plungers are inserted into the rotor.
When the pressure oil is supplied from the pump, the
plungers are pushed. The rotor is installed in the cas-
ing so that the center of the rotor is eccentric from the
center of the casing. Therefore, plunger reciprocating
motion causes the rotor to slide along the inner diame-
ter of the casing. This rotation is transferred to the
travel reduction gear via the coupling.
Casing
Rotor
Joint
Rotor
Coupling
Joint
Coupling
Plunger
T190-03-02-004
Casing
Plunger
Rotor
T190-03-02-005
T3-5-3
COMPONENT OPERATION / Travel Device
PARKING BRAKE
The parking brake is a wet type multi-disc brake. Only
when brake release pressure is routed to the brake
piston chamber, the brake released (negative type).
• EX60-5, EX75URLC-3
Releasing Brake Applying Brake
When the travel function is operated, the travel main When the travel function is stopped, the main hydrau-
hydraulic oil is routed to the brake piston chamber. lic oil pressure in the brake piston decreases.
When the oil pressure overcomes the disc spring Thereby, the brake piston is pushed back by the disc
force, the brake piston is moved toward the disc spring, causing the friction plates and plates to con-
spring, causing the contact between the friction plates tact tightly and the brake to be applied.
and plates to loosen. The brake is released.
Plate
T152-03-05-003
Disc Brake Friction
Spring Piston Plate
T152-03-05-002
T3-5-4
COMPONENT OPERATION / Travel Device
Releasing the Brake: Applying the Brake:
When the travel function is operated, the travel circuit When the travel levers are returned to neutral, the
system pressure is routed to the brake piston cham- system pressure routed in the brake piston chamber
ber through the shuttle valve. Then, when the oil is reduced. Then, the brake piston is returned by disc
pressure overcomes the disc spring force, the brake spring, causing the plates to come into contact with
piston is moved to the left, causing the friction plates the friction plates. Thus, the brake is applied.
and plates to release. Thus, the brake is released.
Disc Spring
Brake Piston
Chamber
Brake Piston
T102-03-04-013
Plate
Friction Plate
T190-03-02-011
T3-5-5
COMPONENT OPERATION / Travel Device
TRAVEL BRAKE VALVE
The travel brake valve consists of the counter balance
valve, check valve, and relief valve.
• EX60-5, EX75URLC-3:
Port A Port B
2
5
Port BV
Port AV
Port AM Port BM
3
4
T152-03-05-004
T3-5-6
COMPONENT OPERATION / Travel Device
• EX75UR-3
1 Port BV
Port AV
Port A Port B 2
5
AM BM
AM BM
3
4
T190-03-02-009
T3-5-7
COMPONENT OPERATION / Travel Device
Circuit Protection
Hydraulic pressure oil in the travel circuit is guided to When the circuit pressure reaches the relief set pres-
poppet 1 via port AC (EX75UR-3: port AM). Pressure sure (spring (5) set pressure), poppet (1) opens to re-
oil is further routed to the bottom side of piston (3) live the hydraulic oil.
through orifices (2 and 4) to move piston (3) upward. As described above, the system relief functions in two
As long as piston (3) is moving, a pressure difference stages, reducing shocks developed when the travel
arises between the upper and lower sides of poppet motor starts or stops.
(1). When the pressure difference overcomes spring
(5) force, poppet (1) opens, allowing hydraulic oil
pressure to relieve to port B side. When piston (3)
moves full stroke and the pressure difference be-
tween the upper and lower sides of poppet (1) is re-
duced, poppet (1) closes until the hydraulic circuit
pressure reaches the relief set pressure.
• EX60-5, EX75URLC-3:
Port A Port B
Port AC
Port BC
1 6
2
7
3 8
4 9
5 10
T152-03-05-004
T3-5-8
COMPONENT OPERATION / Travel Device
• EX75UR-3:
Port A Port B
AM BM
AM BM
1 6
2 7
3 8
4 9
5 10
T190-03-02-009
T3-5-9
COMPONENT OPERATION / Travel Device
TRAVEL REDUCTION GEAR
• EX60-5, EX75URLC-3:
The travel motor rotates shaft (5). This rotation is trans-
ferred to sun gear (8) after its speed is reduced be-
tween first stage planetary gear (3) and first stage car-
rier (6). The rotation speed of sun gear (8) is reduced
again between second stage planetary gear (2) and
second stage carrier (7).
Second stage carrier (7) is secured to the travel motor
casing with knock pin (1) and ring gear (4) is secured
to drum (9) with bolts. Therefore, the rotation of second
stage planetary gear (2) drives sprocket (10) via ring
gear (4) and drum (9).
1 2 3 4
9 8 7 6
10
T152-03-05-004
T3-5-10
COMPONENT OPERATION / Travel Device
• EX75UR-3
The travel motor rotates shaft (5). This rotation power
drives second stage sun gear (8) after the rotation
speed is reduced by first stage planetary gear (3) and
carrier (6). Second stage sun gear (8) rotation speed is
reduced by second stage planetary gear (2) and car-
rier (7).
Ring gear (4) is secured to the travel motor casing with
knock pin (1).
Second stage carrier (7), drum (9) and sprocket (10)
are bolted to the drum, the second stage carrier and
sprocket rotate together.
5 6 4 7 8
9 1 3 2
10
T192-03-05-004
T3-5-11
COMPONENT OPERATION / Travel Device
(Blank)
T3-5-12
COMPONENT OPERATION / Others (Upperstructure)
PILOT SHUT-OFF VALVE
The pilot shut-off valve is a manually-operated switch
valve. The spool in the pilot shut-off valve is rotated by
moving the pilot control shut-off lever to turn the pilot
oil flow to the pilot valves ON or OFF. EX75UR-3:
To the Pilot Valve
EX60-5,EX75URLC-3:
To Pilot Valve
To the
Hydraulic Oil Tank
To Hydraulic Tank
From the
Pilot Pump
From Pilot
Valve
To the 7-Spool
To Shockless Valve Solenoid Valve Unit From the Pilot Valve
From Control
Valve W157-02-08-001
T152-03-06-001
From Pilot Valve
To Pilot Valve
T3-6-1
COMPONENT OPERATION / Others (Upperstructure)
SWING MODE CONTROL VALVE
(EX75UR-3, EX75URLC-3)
The swing mode control valve consists of solenoid Swing Mode Control Circuit (when precise swing
valve (1), spool (2), and spool (3). mode is selected)
The swing mode control valve is operated in the pre- When the precise swing mode switch is turned ON,
cise swing mode, so the swing speed becomes slow. solenoid valve (1) is activated, allowing the pilot pres-
(Refer to SYSTEM / Hydraulic System section.) sure oil to flow through spool (3) from port P and
changing spool (2) position.
Swing Mode Control Circuit (normal) Thereby, the pilot pressure supplied port A1 (A2) is
When the swing control lever is operated, the swing routed to the swing spool in control valve 2 from port
pilot pressure oil is supplied into port A1 (A2). After B1’ (B2’) via spool (2).
going through spool (2), the pilot pressure oil is When shifting the control valve 2 spool, hydraulic oil
routed to the swing spool in control valve 1 via port flows from the main pump 2, and the precise swing
B1 (B2). mode is selected.
When shifting the control valve 1 spool, hydraulic oil
flows from the main pump 1 and normal swing can be
made.
P
Pilot Pressure
B1 2
B1
Left Swing A1 To
Pilot Pressure control B1’
B2 valve 1
To
B2 control
valve 2
Right Swing A2
Pilot Pressure B2’
T192-03-06-003
T3-6-2
COMPONENT OPERATION / Others (Upperstructure)
Swing Parking Brake Release Circuit (when pre-
cise swing mode is selected)
When the swing control lever is operated, the swing
pilot pressure oil is supplied to port A via the shuttle
valve, moving spool (4) to the right. When spool (4) is
moved, the pilot pressure oil flows through spool (4)
from port P and is routed to the swing motor from port
B releasing the swing parking brake.
A
Swing A
Pilot
Pressure
T192-03-06-004
T3-6-3
COMPONENT OPERATION / Others (Upperstructure)
SHOCKLESS VALVE
Two shockless valves are provided (one for boom
raise /lower and arm roll-out, and another for swing
right/left) to regulate the pilot oil flow between the pilot
valve and the control valve so that the spools in the
control valve are moved smoothly. The swing shock-
less valve functions are explained in this section.
T3-6-4
COMPONENT OPERATION / Others (Upperstructure)
T191-03-06-007
9 8
T191-03-06-008
9 8
1
When operating in reverse:
T3-6-5
COMPONENT OPERATION / Others (Upperstructure)
Heating Circuit
when the pilot shut-off valve is in the LOCK position,
hydraulic oil from the pilot pump passes through the
pilot shut-off valve and is routed to the shockless
valve. As hydraulic oil flow is restricted by the orifice
located at the inlet of the shockless valve so that
hydraulic oil is warmed. The warmed hydraulic oil is
routed to the shockless valve and the pilot valve to
warm the components in the pilot system.
Orifice
Pilot Shut-off
Valve
(LOCK
Position)
Pilot Pump
Shockless Valve
T152-03-06-002
T3-6-6
COMPONENT OPERATION / Others (Upperstructure)
(Blank)
T3-6-7
COMPONENT OPERATION / Others (Upperstructure)
7-SPOOL SOLENOID VALVE UNIT 7 6 5 4 3 2 1
(EX75UR-3)
The 7-spool solenoid valve unit consists of the proportional
solenoid valve, shockless valve, pressure sensor, and
pressure switch.
Proportional Solenoid Valve
The proportional solenoid valve is controlled by the cur-
rent signal from the AUTO-MARCCINO control unit and
sends a signal out in proportion to the current signal value.
There are two types of the proportional solenoid valves,
deceleration proportional solenoid valve and acceleration
proportional solenoid valve.
The deceleration proportional solenoid valve is fully
opened when the key switch is ON. Then, in response to T191-03-06-001
current signals from the AUTO-MARCCINO control unit,
the deceleration proportional solenoid valve reduces or
blocks the secondary pilot pressure oil from the pilot valve.
Thereby, the control valve spool is controlled.
The acceleration proportional solenoid valve supplies the
primary pilot pressure from the pilot shut-off valve directly
to the control valve in response to current signals from the
AUTO-MARCCINO control unit. Thereby, the control
valve spool is controlled.
(Refer to the Front Control System Group in SYSTEM Sec-
tion.)
Pilot Valve
To the shockless
Control Valve valve
T191-03-06-002
1 - Left Offset Acceleration 3 - Right Offset Acceleration 5 - Am Roll-In Deceleration 7 - Boom Raise Deceleration
Solenoid Valve Solenoid Valve Solenoid Valve Solenoid Valve
2 - Left Offset Deceleration 4 - Arm Roll-Out Accelera- 6 - Boom Lower Deceleration
Solenoid Valve tion Solenoid Valve Solenoid Valve
T3-6-8
COMPONENT OPERATION / Others (Upperstructure)
Heating Circuit
When the pilot shut-off valve is closed (in the LOCK
position), the pilot pressure oil from the pilot pump
flows through the pilot shut-off valve and is routed to
the 7-spool solenoid valve unit. Then, the pilot pres-
sure oil is restricted and heated by the orifice pro-
vided at the inlet port of the 7-spool solenoid valve
unit. As the warmed up pilot oil is then routed to each
pilot valve, the components in the pilot system are
warmed.
Pilot
Shut-Off
Valve
T192-03-06-002
T3-6-9
COMPONENT OPERATION / Others (Upperstructure)
PILOT RELIEF VALVE
The pilot relief valve regulates the pilot oil pressure to a
set constant pressure.
1 3 4 5 6 7
Pilot Pump
2 5
T191-03-06-010
T3-6-10
COMPONENT OPERATION / Others (Upperstructure)
EC MOTOR
The EC motor is used to control engine speed.
A worm gear is incorporated into the EC motor to pre-
vent the motor from overrunning. The EC sensor is
provided to detect the degrees of the EC motor rotation
to calculate the governor lever position.
(Refer to the Control System Group in SYSTEM Sec-
tion.)
Output
Output Gear Shaft Worm Gear
Motor
T157-02-05-018
Sensor Gear EC Sensor Worm Wheel
T3-6-11
COMPONENT OPERATION / Others (Upperstructure)
(Blank)
T3-6-12
COMPONENT OPERATION / Others (Undercarriage)
SWING BEARING
The swing bearing supports the upperstructure and
allows the upperstructure to rotate smoothly.
This bearing is a single-row shear ball-type bearing,
comprised of the outer race, inner race, balls, supports,
and seals.
The outer race is bolted to the upperstructure and the
inner race is bolted to the undercarriage. The internal
gear on the inner race meshes with the output shaft of
the swing reduction gear.
Outer Race
Seal
Inner Race
Support
Seal
Ball
T102-03-02-001
T3-7-1
COMPONENT OPERATION / Others (Undercarriage)
CENTER JOINT
The center joint is a 360° rotary joint. When the upper-
structure is rotated, the center joint removes the prob-
lem of twisted hoses and allows hydraulic oil to flow
smoothly to and from the travel motors.
Spindle (1) is attached to the main frame, and body (2)
is bolted to the swing center of the undercarriage.
Hydraulic oil flows to left and right travel motors and
blade cylinder via spindle (1) and the oil ports of body
(2). Seals (3) are used to prevent oil leak between
spindle (1) and body (2).
3
Drain
Blade
Lower
Blade
Raise
Drain
T190-03-03-002
T3-7-2
COMPONENT OPERATION / Others (Undercarriage)
TRACK ADJUSTER
CAUTION: The adjuster cylinder contains
The track adjuster consists of spring (5), adjuster
high-pressure grease. If valve (1) is loosened
cylinder (6) and so forth. The track adjuster is installed
excessively or quickly, grease may spout out,
on the side frame. Spring (5) abosorbs the load applied
possibly causing serious personal injury. Be
to the front idler. Track sag is abjusted by adjuster
sure to slowly loosen valve (1) while keeping
cylinder.
body parts and face away from valve (1).
Never loosen the grease fitting.
• When grease is supplied through the grease fitting,
grease fills chamber (a) in adjuster cylinder (6) so
that piston rod (8) is extended to reduce track sag.
• When increasing track sag, rotate valve (1) 1 to 1.5
1
turns counterclockwise to discharge grease.
Grease Fitting
Grease
Discharge Port
M104-07-119
1 2 3 4 a 5 6 7 8
T191-03-07-002
T3-7-3
COMPONENT OPERATION / Others (Undercarriage)
(Blank)
T3-7-4