MASTER DRIVE UNIT

N25XMDR3, N30-40XMR3 [C470];

N50XMA3 [C471];
N30ZDR, N35-40ZR [D470];
N30ZDRS, N35-40ZRS [A265];
N30XMDR3, N45XMR3 [G138];
N30XMXDR3, N45XMXR3 [B264];
N35ZDR, N45ZR [C264]

PART NO. 1523820 630 SRM 1022

 SAFETY PRECAUTIONS
MAINTENANCE AND REPAIR
• When lifting parts or assemblies, make sure all slings, chains, or cables are correctly
fastened, and that the load being lifted is balanced. Make sure the crane, cables, and
chains have the capacity to support the weight of the load.

• Do not lift heavy parts by hand, use a lifting mechanism.

• Wear safety glasses.

• DISCONNECT THE BATTERY CONNECTOR before doing any maintenance or repair

on electric lift trucks. Disconnect the battery ground cable on internal combustion lift
trucks.

• Always use correct blocks to prevent the unit from rolling or falling. See HOW TO PUT
THE LIFT TRUCK ON BLOCKS in the Operating Manual or the Periodic Mainte-
nance section.

• Keep the unit clean and the working area clean and orderly.

• Use the correct tools for the job.

• Keep the tools clean and in good condition.

• Always use HYSTER APPROVED parts when making repairs. Replacement parts
must meet or exceed the specifications of the original equipment manufacturer.

• Make sure all nuts, bolts, snap rings, and other fastening devices are removed before
using force to remove parts.

• Always fasten a DO NOT OPERATE tag to the controls of the unit when making repairs,
or if the unit needs repairs.

• Be sure to follow the WARNING and CAUTION notes in the instructions.

• Gasoline, Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG), and Diesel fuel
are flammable. Be sure to follow the necessary safety precautions when handling these
fuels and when working on these fuel systems.

• Batteries generate flammable gas when they are being charged. Keep fire and sparks
away from the area. Make sure the area is well ventilated.

NOTE: The following symbols and words indicate safety information in this
manual:

WARNING
Indicates a condition that can cause immediate death or injury!

CAUTION
Indicates a condition that can cause property damage!
Master Drive Unit Table of Contents

TABLE OF CONTENTS

HFK400 Master Drive Unit............................................................................................................................... 1

General ........................................................................................................................................................... 1
Description ..................................................................................................................................................... 1
Drive Unit Maintenance and Repair ............................................................................................................ 2
Remove....................................................................................................................................................... 2
Install ......................................................................................................................................................... 3
Disassemble ............................................................................................................................................... 4
Assemble .................................................................................................................................................... 7
Troubleshooting ............................................................................................................................................. 15
GK Master Drive Unit ....................................................................................................................................... 17
General ........................................................................................................................................................... 17
Description ..................................................................................................................................................... 17
Maintenance and Repair ............................................................................................................................... 18
Install ............................................................................................................................................................. 19
Assemble ........................................................................................................................................................ 19
Mounting Electric Motor........................................................................................................................... 20
Pivoted Connection - Geared Steering ..................................................................................................... 20
Disassemble ................................................................................................................................................... 20
Troubleshooting ............................................................................................................................................. 21

This section is for the following models:

N25XMDR3, N30-40XMR3 [C470];

N50XMA3 [C471];
N30ZDR, N35-40ZR [D470];
N30ZDRS, N35-40ZRS [A265];
N30XMDR3, N45XMR3 [G138];
N30XMXDR3, N45XMXR3 [B264];
N35ZDR, N45ZR [C264]

©2006 HYSTER COMPANY i

"THE
QUALITY
KEEPERS"

HYSTER
APPROVED
PARTS
630 SRM 1022 HFK400 Master Drive Unit

HFK400 Master Drive Unit

GENERAL

CAUTION
Some of the hardware used on the MDU and
traction motor is metric. Use the correct tool
to avoid damage.

This section contains a description, repair, and ad-

justment procedures for the parts of the HFK400
master drive unit (MDU) used on the narrow aisle
and grocery reach lift trucks. The traction motor,
steering, and brake repair information are in sepa-
rate manuals.

DESCRIPTION
The main component parts of the MDU are the case,
the motor pinion and large gear set, the pinion and
spiral bevel gear set, the bearings, and the axle and
wheel. See Figure 1. The traction motor fastens to an
adapter ring fastened to the MDU. This adapter ring
is part of the large ball bearing and allows the MDU
to turn on the axis of the traction motor for steering.
The traction motor does not turn with the MDU.

Six capscrews fasten the large ball bearing and MDU

to the articulating axle. There is a small pinion gear
on the traction motor armature shaft. This gear
turns a large gear on the pinion shaft in the MDU.
The pinion shaft turns a spiral bevel gear on the axle
to turn the drive wheel. The brake is fastened to the
other end of the traction motor shaft and provides
friction for braking to stop rotation of the shaft. The
braking action works through the gears to stop the
unit.

Figure 1. Master Drive Unit With Motor and

Wheel

1
HFK400 Master Drive Unit 630 SRM 1022

DRIVE UNIT MAINTENANCE AND REPAIR drain plug. Tighten the drain plug to 22 N•m
(16 lbf ft).
Remove
6. Remove the six capscrews and lockwashers that
fasten the traction motor to the adapter ring on
WARNING
the MDU. Carefully lift the motor and set the mo-
The lift truck and components are heavy. tor out of the way. DO NOT damage the pinion
Be sure that all lifting devices (hoists, ca- gear on the motor shaft. Use a rope to fasten the
bles, chains, slings, etc.) are suitable and motor to prevent the motor from falling. See Fig-
of adequate capacity to lift the lift truck or ure 2.
component. The lift truck can weigh up to
approximately 3541 kg (7800 lb) empty.

1. Move the steering control so the drive wheel is in

a position for straight travel.

WARNING
Disconnect the battery and separate the con-
nector before opening the drive unit compart-
ment door and before inspecting or repairing
the electrical system. If a tool causes a short
circuit, the high-current flow from the battery
can cause injury or parts damage.

2. Disconnect and remove the battery. Use the

battery removal procedure described in either
the Operating Manual or the section Periodic
Maintenance 8000 SRM 970.

3. Remove the electrical compartment cover for ac-

cess to the traction motor controller. Remove the
capscrews retaining the cover to the frame.

WARNING
The capacitor in the traction motor controller
can hold an electrical charge after the battery
is disconnected. To prevent electrical shock 1. TRACTION MOTOR 8. LOCKWASHER
or injury, discharge the capacitor before in- 2. CAPSCREW 9. NUT
specting or repairing any component. Wear 3. LOCKWASHER 10. WHEEL NUT
4. CAPSCREW 11. WHEEL
safety glasses. Make certain the battery has 5. LOCKWASHER 12. DRIVE UNIT
been disconnected. Discharge the capacitors 6. O-RING 13. ARTICULATING
in the controller by connecting a load (such as 7. PINION GEAR AXLE
a contactor coil or horn) across the controller’s
B+ and B terminals (center two terminals). Figure 2. Separating Traction Motor
DO NOT use a screwdriver to discharge the
7. Loosen the lock nut at the chain anchor for the
traction motor controller.
steering chain. Remove the capscrew at the
4. Discharge the traction motor controller by con- chain anchor. Put a mark on the MDU for the
necting a load across terminals B+ and B . location of the pin that fastens the chain anchor
to the sprocket. Remove the pin. Carefully
5. Open the drive unit compartment door. Fasten remove the chain anchor and chain from the
the door so that it is fully open. Put a pan under sprocket. Refer to the section Steering System
the MDU drain plug and remove the drain plug. 1600 SRM 974.
After the oil has completely drained, install the

2
630 SRM 1022 HFK400 Master Drive Unit

4. Install the six capscrews and lockwashers that

WARNING fasten the adapter ring and MDU to the frame
There are close clearances between the MDU, or axle plate. Use a cross pattern to tighten the
drive chassis, and base arm that can cause se- capscrews to 25 N•m (18 lbf ft). Make sure the
rious injury. NEVER put hands, arms, head, or large ball bearing and adapter ring are in the cor-
legs between these parts unless the parts have rect position around the complete circumference.
blocks to prevent movement. If the MDU falls, Use the cross pattern to tighten the capscrews to
it can cause an injury. Support the MDU verti- 68 N•m (50 lbf ft).
cally to prevent it from falling.
5. If the pinion gear on the motor shaft was re-
8. Place a sling under the lift truck frame on the moved, install the key, gear, lockwasher, and nut.
mast side of the MDU. Make sure the lifting de- Tighten the nut to 54 N•m (40 lbf ft). If an impact
vice and sling have the ability to lift approxi- wrench is used, make sure it does not tighten the
mately 3541 kg (7800 lb). nut to more than the correct torque.
9. Remove the six capscrews and lockwashers that 6. Install a new O-ring on the motor using O-ring
fasten the adapter ring and MDU to the articu- lubricant. Carefully install and align the motor
lating axle. on the adapter ring and MDU. DO NOT damage
the pinion gear on the motor shaft or the large
10. Hold the MDU and raise the truck frame so that gear of the MDU. Install the six capscrews and
the MDU is free. The steer axle will pivot on the lockwashers. Tighten the capscrews to 20 N•m
articulation shaft. Lower the MDU to the floor (15 lbf ft).
and move it from under the lift truck. Lower the
lift truck frame on blocks. 7. Make sure the MDU is in the position for straight
travel with the tire to the left of the case (facing
Install MDU). Carefully install the steering chain. Use
the pin to install the chain anchor on the adapter
WARNING ring. Use the capscrew to fasten the two chain
The lift truck and components are heavy. anchors together. Adjust the steering chain,
Be sure that all lifting devices (hoists, ca- steering potentiometer, and limit switches using
bles, chains, slings, etc.) are suitable and the procedures in the section Steering System
of adequate capacity to lift the lift truck or 1600 SRM 974.
component. The lift truck can weigh up to
approximately 3541 kg (7800 lb) empty. CAUTION
The steering system MUST be adjusted before
1. Use a crane and chain or sling with a capacity
operating the lift truck.
rating of 3541 kg (7800 lb) to lift the frame. Lift
the frame for clearance to slide the MDU un- 8. Lubricate the large ball bearing using the proper
der the frame or steer axle. Temporarily install grease. Fill the MDU to the level/fill plug using
blocks under the frame to prevent lowering. Lay the proper oil. The proper lubricants are listed in
the MDU on the floor. Slide the MDU under the the Operating Manual or the section Periodic
drive chassis. Maintenance 8000 SRM 970. Add oil slowly.
The oil passes through the bearings to the lower
2. Move the MDU into approximate alignment un-
part of the MDU.
der the frame or axle plate.
9. Install the battery and close the drive unit com-
3. Hold the MDU in the vertical position through
partment doors. Install the electrical compart-
the hole in the plate. DO NOT put any part
ment cover. Connect the battery connector.
of your body between the MDU and the frame
or axle plate. Carefully raise the frame and re-
move the blocks. Carefully lower the frame and
align the capscrew holes in the large ball bear-
ing, adapter ring, and frame or axle plate.

3
HFK400 Master Drive Unit 630 SRM 1022

Disassemble 3. The upper housing is retained to the lower hous-

ing with two dowel pins. Use a plastic hammer
1. Remove the wheel nuts and the drive/steer against the lower portion of the upper housing to
wheel. separate the upper housing from the lower hous-
ing. Carefully slide the upper housing for clear-
2. Remove the nine capscrews that fasten the lower
ance between the upper housing and helical gear.
housing to the upper housing. Remove the four
Remove the upper housing.
capscrews inside the upper housing. See Fig-
ure 3. There are also two capscrews inside the
case that are secured with washers and nuts on CAUTION
the opposite side of the upper housing. Make The helical gear and pinion shaft assembly can
certain to remove the capscrews, lockwashers, only be removed after the bevel gear and axle
and nuts before attempting to separate the up- shaft have been removed from the drive unit
per housing from the lower housing. lower housing.

4. Remove the capscrews retaining the drive unit

cover. Remove the drive unit cover.

5. Install two wheel nuts on to the wheel bolts. Po-

sition a piece of wood or bar between the nuts
to retain the drive axle while removing the spe-
cial capscrew retaining the bevel gear to the axle
shaft. Remove the special capscrew (24 mm) and
the special washer.

WARNING
Toxic vapors may be generated by heating the
axle shaft to remove the Loctite® adhesive.
Wear a protective mask during this operation.
Use gloves to remove the bevel gear if it has
been heated.

NOTE: The bevel gear is secured to the axle shaft us-

ing Loctite® 270. It may be necessary to use a weld-
ing torch to heat the bevel gear to 100 to 120 C (212
to 248 F) to free the bevel gear from the axle shaft.

6. Use a strap wrench or place a wood wedge under

the helical gear to keep the gear from rotating.
Remove the nut retaining the helical spur gear.
Use a gear puller to remove the helical gear from
the pinion shaft. Carefully remove the pinion
1. TOP CASE shaft and bearing cone from the lower housing.
2. CAPSCREWS INSIDE TOP CASE Use a plastic hammer, if necessary. Remove the
3. BOTTOM CASE spacer bushing from the pinion shaft.
4. CAPSCREWS (3 EACH SIDE)
5. CAPSCREW (CENTER)
6. CAPSCREW IN PIN
7. SPACER

Figure 3. Separating Cases

4
630 SRM 1022 HFK400 Master Drive Unit

7. Use a copper mandrel and a plastic hammer to 11. Remove the wheel bolts from the axle shaft, us-
drive the axle shaft out of the lower housing. Re- ing a hydraulic press, if necessary. See Figure 5.
move the bevel pinion out of the lower housing.
12. If necessary, remove the bearing cups. See Fig-
ure 6. Use a puller or copper mandrel and a plas-
CAUTION tic hammer. DO NOT damage or lose the shims
Keep all shim sets together and labeled for cor- between the cups and the bore in the case. Keep
rect location and installation during assembly. each set of shims together and separate from the
other sets of shims. Put a label on each set so that
NOTE: If the bevel pinion and gear set will NOT be the sets can be installed in the correct position
replaced, the same shim sets can be used during as- during assembly. Measure the distance between
sembly. Adjustment will not be necessary. the edge of the case and the inner seal ring at the
axle bore. The replacement seal ring MUST be
8. If necessary, remove the bearing cones from the
installed in the same position as the old seal. Re-
axle shaft, the bevel gear, and the bevel pinion
move the seal ring.
shaft. To remove the bearing cone from the axle
shaft, it is necessary to cut the bearing cage, then
open the cage and remove the rollers. Use a
puller to remove the cage from the axle shaft.

9. Remove the bearing shield from the lower hous-

ing using a plastic hammer. See Figure 4.

10. If necessary, remove the motor nut, lockwasher,

bevel pinion, and key from the motor shaft. Re-
move the O-ring from the motor.
Figure 4. Removing Bearing Shield

5
HFK400 Master Drive Unit 630 SRM 1022

Figure 5. Master Drive Unit Parts

6
630 SRM 1022 HFK400 Master Drive Unit

Legend for Figure 5

1. SCREW 19. SHIM
2. CENTERING RING 20. PLUG/OIL DRAIN
3. SOCKET HEAD SCREW 21. SEAL RING
4. WASHER 22. CAPSCREW
5. NUT 23. COVER
6. SOCKET HEAD SCREW 24. WHEEL SHAFT
7. SOCKET HEAD SCREW 25. WHEEL STUD
8. SOCKET HEAD SCREW 26. SEALING RING
9. DOWEL PIN 27. BEARING
10. UPPER HOUSING 28. SHIM
11. BREATHER VALVE 29. OIL RING
12. PLUG/OIL FILL 30. SEALING RING
13. SEAL RING 31. CAPSCREW
14. LUBE FITTING 32. DISK
15. PINION GEAR 33. RING AND PINION
16. LOCK NUT 34. BEARING
17. GEAR 35. SHIM
18. BEARING 36. LOWER HOUSING
Assemble

WARNING
Cleaning solvents can be flammable and toxic
and can cause skin irritation. When using
cleaning solvents, always follow the recom-
mendations of the manufacturer. Wear eye
protection.

CAUTION
Some of the hardware used on the master drive
unit (MDU) and traction motor is metric. Use
the correct tool to avoid damage.

NOTE: The pinion gear and the large gear MUST be

replaced as a set. The spiral bevel pinion and gear
set MUST be replaced as a set.

NOTE: The large ball bearing is part of the top case.

The top case and the ball bearing are replaced as a
unit.

1. Clean all components thoroughly. Use Loctite®

Fast Cleaner No. 706 to remove all traces of ad-
1. UPPER PINION BEARING CUP hesive from the lower housing in the area where
2. LOWER PINION BEARING CUP the thread-protecting shield had been located.
3. INNER AXLE SHAFT BEARING CUP
4. OUTER AXLE SHAFT BEARING CUP Spray the cleaner from a distance of approxi-
5. UPPER PINION BEARING SHIMS mately 30 cm (12 in.) while holding the can up-
6. LOWER PINION BEARING SHIMS right. Allow the cleaner to work; then thoroughly
7. INNER AXLE SHAFT SHIMS remove the dissolved dirt from the lower housing
8. OUTER AXLE SHAFT SHIMS using a clean cloth. Spray the surface with the
9. INNER SEAL RING
10. BEARING SHIELD cleaner again and allow to air-dry.

Figure 6. Bearing and Shim Location 2. Check all parts for damage or cracks. Replace
any damaged parts.

7
HFK400 Master Drive Unit 630 SRM 1022

indicator. The procedure below specifies the use of

CAUTION a special measuring tool (Hyster P/N 2036120) and
The axle and gear assemblies are installed and a special clamping tool (Hyster P/N 2036121). The
removed several times during this procedure. measuring tool can be fabricated, if desired, as fol-
Be careful not to damage the seals. lows: Make a bushing to fit the bore of the lower pin-
ion shaft bearing. The bushing must have an out-
NOTE: The helical pinion and gear and the bevel side diameter of 51.5 mm (2.03 in.) and a length of
pinion shaft and bevel gear are matched sets and 67.5 mm (2.66 in.). The special clamping tool can be
MUST be replaced as sets. When replacing the gear used to facilitate easy assembly.
sets, always replace the tapered roller bearings. The
bearing cup and bearing cone MUST be from the 3. Insert the special measuring tool in the pinion
same manufacturer. Lubricate the bearings with shaft lower bearing bore. Determine the correct
clean transmission oil prior to assembly. thickness for the lower bearing shim set (dimen-
sion X) as follows (see Figure 7):
NOTE: Assembly of the drive unit requires the use
of a standard micrometer, torque wrench, and dial

NOTE: THERE ARE TWO NUMBERS STAMPED ON THE BEVEL PINION SHAFT. THERE ARE ALSO TWO
NUMBERS STAMPED ON THE BEVEL GEAR. ONE NUMBER ON EACH PART IS THE SET NUMBER. THESE
NUMBERS MUST BE THE SAME. CHECK THAT THE BEVEL PINION SHAFT AND THE BEVEL GEAR ARE
A MATCHED SET BY COMPARING THE SET NUMBERS. THE SECOND NUMBER ON THE BEVEL PINION
SHAFT IS THE ASSEMBLY DIMENSION OF THE SHAFT (DIMENSION B, BELOW). THE SECOND NUMBER
ON THE BEVEL GEAR IS THE GEAR CLEARANCE NUMBER.
1. BEVEL PINION SHAFT 6. LOWER BEARING SHIM SET
2. SPACER 7. UPPER BEARING SHIM SET
3. SPECIAL MEASURING TOOL 8. UPPER BEARING
4. LOWER CASE 9. DIMENSION B (MM) STAMPED ON END OF
5. LOWER BEARING BEVEL PINION SHAFT

Figure 7. Bevel Pinion Shaft Installation

8
630 SRM 1022 HFK400 Master Drive Unit

a. Measure dimension F (the difference be-

tween the axle bearing bore and the end of
the bushing).

b. Subtract the value F from the length (L) of

the bushing.

c. Add the value of d/2. The result is dimension

E.
E = L F + d/2
L = bushing length
F = the difference between the bearing bore
for the axle and the end of the bushing
d/2 = 45.00 mm (1.7716 in.)

d. Measure dimension T (the width of the lower

bearing).

e. Subtract assembly dimension B (stamped

on the bevel pinion shaft) from dimension 1. BEARING CUP
E (found in Step c, above). Then subtract 2. WHEEL SHAFT INNER BEARING BORE SHIM
dimension T. The result is dimension X (the SET
3. WHEEL SHAFT OUTER BEARING BORE SHIM
correct thickness of the lower bearing shim SET
set).
X=E B T Figure 8. Wheel Shaft Shim Sets
E = the value found in Step c
B = the number stamped on the pinion shaft 6. Install the shim set removed during disassembly
T = the total thickness of the bearing from the outer bearing bore of the wheel shaft
into the outer bearing bore. This shim set will be
4. Assemble the proper combination of shims to used for the preliminary adjustment of the wheel
equal the correct thickness for the lower bear- shaft. Press the outer bearing cup into the outer
ing shim set, as determined above [±0.05 mm bearing bore. See Figure 8.
(0.002 in.)]. Install the lower bearing shim set
into the lower bearing bore. Press the lower NOTE: DO NOT install the wheel shaft seal until
bearing cup into the bore. after the adjustment procedure has been completed.

7. Press the taper roller bearing cone up to the stop

CAUTION on the pinion shaft.
DO NOT use damaged or distorted shims in the
following steps. 8. Lubricate the bearing cup with transmission
oil. Install the pinion shaft into the housing
5. Install the shim set removed during disassembly and preload it against the bearing cup with the
from the inner bearing bore of the wheel shaft special clamping tool or a piece of wood.
into the inner bearing bore. This shim set will be
used for the preliminary adjustment of the wheel 9. Measure distance A between the top of the shoul-
shaft. Drive the inner bearing cup into the inner der of the pinion shaft and the bottom of the bore
bearing bore. See Figure 8. for the upper bearing. See Figure 9.

9
HFK400 Master Drive Unit 630 SRM 1022

Figure 9. Shim Measurement Figure 10. Pinion Shaft Bearing Clearance

Check
10. Add 0.02 mm (0.00079 in.) to the value of dimen-
sion A and install a shim set equal to that sum 16. Remove the pinion shaft and bearing. Remove
into the bearing bore. the upper bearing cup. Additional shims must
Shim set (mm) = A + 0.02 mm be added to the upper bearing bore to preload
the bearing. To determine the correct amount
11. Press the upper bearing cup into the bearing of additional shims, add 0.07 mm (0.0028 in.) to
bore. Press the upper bearing cone onto the the clearance value measured in Step 15. Install
pinion shaft up to the stop. shims equal to that sum into the bearing bore
with the shims installed earlier.
12. Place the helical gear onto the pinion shaft and
Additional shim set (mm) = value measured on
install the nut. Hold the helical gear with a strap
dial indicator + 0.07 mm
wrench and tighten the nut to a torque value of
150 N•m (111 lbf ft). DO NOT stake the nut. The If no clearance was measured, add a total of
bearing clearance must be checked and adjusted 0.02 mm (0.00079 in.) to the shims installed
before staking the nut. earlier.
13. Remove the special clamping tool or piece of wood 17. Install the pinion shaft. Press the upper bearing
holding the pinion shaft in place. cup into the bearing bore. Press the upper bear-
ing cone onto the pinion shaft up to the stop.
14. Press the pinion shaft downward by hand while
turning the shaft several times to align the taper 18. Cover the splines of the helical gear with a thin
rollers within the bearing. coat of Loctite® 270. Wipe off any excess with a
rag.
15. Place the dial indicator on the housing as shown
in Figure 10. Adjust the dial to indicate zero. 19. Place the helical gear onto the pinion shaft and
Mark the point of measurement on the helical install the nut. Hold the helical gear with a strap
spur gear with a colored pencil. Lift the pinion wrench and tighten the nut to a torque value of
shaft upward by carefully prying up beneath the 150 N•m (111 lbf ft). Stake the nut to the pinion
helical spur gear with two levers. Read any de- shaft.
flection on the dial indicator. This value is the
bearing clearance. Repeat the procedure to be 20. Press the wheel bolts into the wheel shaft until
sure to obtain the correct value. the bolt contacts the stop. Be sure the flattened
side of the bolt faces the wheel shaft center.

10
630 SRM 1022 HFK400 Master Drive Unit

21. Push the sealing ring onto the wheel shaft. 28. Check the tooth contact pattern by coating three
Press the outer wheel bearing cone onto the to four tooth flanks of the bevel gear with ink.
wheel shaft until the bearing contacts the stop. Mesh the coated teeth with the pinion gear sev-
Wait to grease the bearing until after the preload eral times and then inspect the wear pattern of
adjustments are performed. the ink on the coated teeth. Slight deviations
from the ideal tooth contact pattern are admis-
NOTE: After the proper backlash has been obtained, sible. Significant tooth contact pattern misalign-
grease the seal ring and fill the outer bearing cone ment is an indication that a mistake was made
using Shell Alvania R3 grease prior to assembly. at an earlier step in the procedure and will ne-
cessitate repeating the assembly procedure. See
22. Press the inner wheel bearing cone onto the bevel
Table 1.
gear until the bearing cone contacts the stop.

23. Insert the bevel gear into the MDU housing.

NOTE: DO NOT install the inner seal ring until the

bearing preload has been adjusted.

24. Insert the wheel shaft into the housing and en-
gage the splines of the shaft into the bevel gear.
Secure the bevel gear on the wheel shaft using
the M16 capscrew and special washer.

25. Prevent the axle from turning. Tighten the M16

capscrew to 245 N•m (181 lbf ft).

26. Use a dial indicator to check the backlash

between the bevel gear and the pinion. The
backlash is the clearance between the teeth of 1. SPIRAL BEVEL GEAR
the bevel gear and the teeth of the pinion gear. 2. DIAL INDICATOR
See Figure 11. Position the dial indicator on the 3. WOOD WEDGE
housing so that the dial indicator foot is as close Figure 11. Checking Backlash
as possible to being perpendicular to the tooth
flank of the bevel gear. Install a wood wedge 29. Check the wheel bearing clearance. Press down
under the large gear at the top of the MDU to on the wheel shaft by hand and rotate it several
keep the gear and pinion from moving. times. Arrange the dial indicator on the housing
as shown in Figure 12. Adjust the dial to indi-
27. Adjust the dial indicator to zero. Turn the cate zero. Lift the wheel shaft upward by care-
wheel shaft in both directions to measure any fully prying up beneath the bevel gear with two
deflection. The admissible range for backlash is levers. Read any deflection on the dial indicator.
between 0.03 to 0.11 mm (0.0012 to 0.0043 in.). This value is the bearing clearance. Repeat the
Backlash is adjusted by adding or removing procedure to be sure to obtain the correct value.
shims beneath the inner wheel bearing cup. The
ideal backlash is 0.07 mm (0.028 in.).

11
HFK400 Master Drive Unit 630 SRM 1022

Table 1. Tooth Contact Pattern

Correct Contact Pattern Step 1. Apply a colored dye or grease to

approximately 12 of the teeth of the spiral
bevel gear.
Step 2. Apply a small friction load to the
edge of the gear so that the gear does not
turn easily. Rotate the gear one revolution
by turning the large gear on the spiral bevel
pinion.
Step 3. Check the tooth contact pattern on
the spiral bevel gear. Make sure that the
pattern is checked on the side of the tooth
where the pinion teeth apply the force.
Wrong Tooth Contact Pattern
Tip Contact The spiral bevel pinion is too far from
the center of the spiral bevel gear. Some
movement in the direction of the arrows can
be necessary. Adjust the thickness of the
shim as described in the assembly procedure.

Base Contact The spiral bevel pinion is too close to

the center of the spiral bevel gear. Some
movement in the direction of the arrows
can be necessary. Adjust the thickness of
the shim sets as described in the assembly
procedure.

Inner Contact The spiral bevel pinion is too far from the
center of the spiral bevel pinion. Some
movement of the spiral gear away from the
spiral bevel pinion can be necessary. Adjust
the shim sets at the spiral bevel gear as
described in the assembly procedure.

Outer Contact The spiral bevel pinion is too far from the
center of the spiral bevel pinion. Some
movement of the spiral gear toward the
spiral bevel pinion can be necessary. Adjust
the shim sets at the spiral bevel gear as
described in the assembly procedure.

12
630 SRM 1022 HFK400 Master Drive Unit

a shim from beneath the inner bearing cup, you

must add it to the shims beneath outer bearing
cup). The ideal backlash is 0.07 mm (0.003 in.).

34. After the proper backlash and preload have been

obtained, remove the bevel gear and wheel shaft
in order to mount the thread-protective shield
and the radial shaft seal.

35. Thoroughly clean the seat of the thread-protec-

tive shield on the housing with Loctite® Fast
Cleaner 706 or equivalent.

36. Coat the seat of the thread-protective shield with

Figure 12. Wheel Shaft Bearing Clearance
Loctite® 270. Press the thread-protective shield
Check
on the lower housing as far as possible. See Fig-
30. Remove the wheel shaft and outer bearing. Re- ure 13.
move the outer bearing cup. Add or remove
shims as required to obtain a bearing clear-
ance of 0.02 mm (0.00079 in.). Install the outer
bearing cup, bearing, and wheel shaft. Repeat
Step 29. After the bearing clearance is confirmed
to be 0.02 mm (0.00079 in.), remove the wheel
shaft, outer bearing, and outer bearing cup
again. Add 0.10 mm (0.004 in.) additional shims
to the outer bearing bore to preload the bearing.

31. Install the outer bearing cup, outer bearing, and

wheel shaft. Verify that the wheel shaft can be
turned by hand. If not, reduce the preload set
in the previous step in 0.01 mm (0.00039 in.) in-
crements until the wheel shaft can be turned by
hand.

32. After the bearing preload has been properly set,

check the backlash again. Use a dial indicator to
check the backlash between the bevel gear and 1. RADIAL SHAFT SEAL
the pinion. The backlash is the clearance be- 2. THREAD-PROTECTIVE SHIELD
tween the teeth of the bevel gear and the teeth of
the pinion gear. See Figure 11. Position the dial Figure 13. Inner Seal Installation
indicator on the housing so that the dial indicator
foot is as close as possible to being perpendicular 37. Remove the outer bearing cup and shims. Thinly
to the tooth flank of the bevel gear. Install a wood coat the radial shaft seal with Loctite® 574. In-
wedge under the large gear at the top of the MDU stall the inner seal into the lower housing. The
to keep the gear and pinion from moving. inner seal should be 3.0 mm (0.118 in.) below
the bottom edge of the outer bearing bore, when
33. Adjust the dial indicator to zero. Turn the wheel properly installed. See Figure 13. Install the
shaft in both directions to measure any deflec- shims and outer bearing cup.
tion. The admissible range for backlash is be-
tween 0.03 to 0.11 mm (0.0012 to 0.0043 in.). If 38. Coat the entire surface of the inner splines of the
the backlash needs to be adjusted at this point, bevel gear with Loctite® 270. Insert the bevel
the total thickness of the outer plus the inner gear in the housing. See Figure 13.
shims must remain constant (i.e., if you remove

13
HFK400 Master Drive Unit 630 SRM 1022

c. The maximum trunnion bearing clearance is

exceeded. Check the clearance as described
below.

45. Clamp the upper part of the MDU to an assembly

table. Install three eyebolts into the outer race
of the trunnion bearing and rotate the bearing
several times. See Figure 15.

1. M16 CAPSCREW 5. WHEEL SHAFT

2. SPECIAL WASHER 6. GREASE
3. BEVEL GEAR 7. LOCTITE® 270
4. HOUSING

Figure 14. Wheel Shaft Assembly

39. Fill the inner seal ring and the cone on the wheel
shaft with Shell Alvania R3 grease. See Fig-
ure 14.

40. Insert the wheel shaft into the housing and en-
gage the splines of the shaft into the bevel gear. Figure 15. Wheel Shaft Assembly
Remove excess with a clean cloth. 46. Install a cable in each eye bolt. Position three
41. Secure the bevel gear on the wheel shaft using dial indicators on the trunnion bearing and set
the M16 capscrew and special washer. Prevent the indicators to zero. Mark the position of one
the axle from turning. Tighten the M16 capscrew dial indicator on the trunnion bearing with a
to 245 N•m (181 lbf ft). marking pen.

42. Coat the flat housing surface with Loctite® 574 47. Raise the upper housing using a lifting device
before mounting the housing cover. Apply one and a spring balance to obtain approximately
drop of Loctite® 243 to the threads of each of 50 kg (110 lb) of force. Rotate the trunnion
the housing cover mounting bolts and install the bearing several times and position at the mark
bolts. again. The maximum bearing clearance is
0.03 mm (0.0012 in.). If the bearing clearance
NOTE: If the tapped holes in the bottom of the lower is more than the recommended clearance, the
housing extend through the housing, completely seal trunnion bearing and upper housing must be
the capscrews with Loctite® adhesive to prevent oil replaced.
from leaking from around the threads.
NOTE: The large ball bearing is part of the upper
43. Tighten the housing cover capscrews to 9.5 N•m housing. The upper housing and the ball bearing are
(7 lbf ft). replaced as a unit.

44. Inspect the upper part of the MDU. The upper 48. Install the drive venting filter as far as possible
part of the MDU must be replaced if: into the upper part of the MDU. Install grease
fitting. See Figure 16.
a. The caulked cover plate on the trunnion bear-
ing has separated. Check visually.

b. The trunnion bearing is difficult to turn or

binds. Check manually.

14
630 SRM 1022 HFK400 Master Drive Unit

23 N•m (17 lbf ft). Tighten the 10 mm capscrews

to 46 N•m (34 lbf ft). Install the socket head
capscrews, the washers, and the nuts. Tighten
the nuts to 23 N•m (17 lbf ft).

50. Install the wheel and the lug nuts. Tighten the
nuts in a cross pattern to one-half the torque
value specified in Section 2. Tighten the lug nuts
again using the cross pattern to obtain the proper
torque.

51. Lubricate trunnion bearing using the recom-

mended grease listed in Section 2. Add the
grease through both fittings. Slowly rotate the
1. DRIVE VENTING FILTER
2. GREASE FITTING MDU while filling the fittings with grease. A
dry bearing will take approximately 55 grams
Figure 16. Drive Venting Filter and Grease (0.12 lb) of grease to fill the bearing completely.
Fitting Installation
52. Fill the MDU to the level/fill plug using the rec-
49. Use Loctite® 574 to install the upper housing ommended oil listed in Section 2. Add the oil
on the lower housing. Make sure the upper slowly. The oil must go through the bearings to
housing is aligned correctly and use a punch the lower part of the MDU. Fill until the oil just
to install the two dowels if removed. Install starts to run out. Install the plug and tighten to
the capscrews. Tighten the 8 mm capscrews to 22 N•m (16 lbf ft).

TROUBLESHOOTING

PROBLEM POSSIBLE CAUSE PROCEDURE OR ACTION

Lift truck will not move. Traction motor not operating. Repair or replace traction motor.

Damaged gears or bearings. Replace gears or bearings.

MDU makes noise. Insufficient lubricant or incorrect lu- Lubricate as needed.

bricant.

Dry, damaged, or incorrect bearings. Lubricate as needed.

Bearing preload or backlash not Adjust backlash.

properly adjusted.

Worn or damaged gears. Replace gears.

Oil leaks at the housing Housing cover is not sealed or prop- Seal properly.
cover. erly seated.

Capscrews not sealed off or not tight- Tighten to appropriate torque.

ened to specified torque.

15
HFK400 Master Drive Unit 630 SRM 1022

PROBLEM POSSIBLE CAUSE PROCEDURE OR ACTION

Oil leaks at the wheel shaft. Shaft seal incorrectly mounted or Replace shaft seal.
damaged.

Surface of axle shaft damaged. Replace axle shaft.

Oil leaks at the filler plug or Dirt between sealing ring and hous- Clean sealing ring and housing.
drain plug. ing.

Plugs not tightened to specified Tighten plugs to appropriate torque.

torque.

Oil leakage between lower Sealing surface not sealed off. Seal properly.
and upper housings.

Capscrews not tightened to specified Tighten to appropriate torque.

torque.

Oil leaks in motor compart- Too much oil in MDU. Drain excess oil.
ment.

Breather defective. Clean or replace breather.

Traction motor seal defective. Replace motor seal.

Trunnion bearing difficult to Centering ring separated, allowing Torque capscrews holding centering
turn, binds, or exceeds max- dirt to penetrate into bearing. ring to MDU.
imum clearance.

Cage segments are damaged. Replace cage segments.

Deformation of the balls or ball Replace balls and ball races.

races.

Bearing not properly lubricated. Lubricate as needed.

16
630 SRM 1022 GK Master Drive Unit

GK Master Drive Unit

GENERAL Some of the hardware used on the MDU and
traction motor is metric. Use the correct tool
This section contains a description, repair, and ad- to avoid damage.
justment procedures for the parts of the GK master
drive unit (MDU) used on the narrow aisle lift trucks. The GK MDU is vertically installed in the truck and
The traction motor, steering, and brake repair infor- allows an effective utilization of space. The com-
mation are in separate manuals. pact, one-piece housing is made of high-duty nodular
iron; thus having a high rigidity and optimum guid-
DESCRIPTION ing precision. This allows a fully integrated bearing
of the helical spur gear stage with a very high run-
CAUTION ning smoothness; i.e., no drive pinion on the motor
shaft of the electric motor. See Figure 17.
Certain specifications and procedures differ
depending upon the type of master drive unit. The MDU consists of two ratio steps. Gear ratio 1 is
Verify the type of MDU by inspecting the hous- designed as helical spur gear stage and permanently
ing. integrated in the housing. Gear ratio 2 is designed as
Gleason bevel gearing of the hypoid type with offset
bevel pinion shaft.

1. MDU HOUSING 6. WHEEL SHAFT

2. VENT HOLE 7. INPUT PINION
3. GEAR RIM 8. HOUSING COVER
4. STEERING PINION 9. OIL FILLER PLUG
5. STEERING BEARING 10. OIL DRAIN PLUG

Figure 17. GK Master Drive Unit

17
GK Master Drive Unit 630 SRM 1022

MAINTENANCE AND REPAIR

WARNING
The lift truck and components are heavy. All
lifting devices (hoists, cables, chains, slings,
etc.) must be suitable and of adequate capac-
ity to lift the lift truck or component. The lift
truck can weigh up to approximately 3541 kg
(7800 lb) empty.

1. Move the steering control so the drive wheel is in

a position for straight travel.

WARNING
Disconnect the battery and separate the con-
nector before opening the drive unit compart-
ment door and before inspecting or repairing
the electrical system. If a tool causes a short
circuit, the high-current flow from the battery
can cause injury or parts damage.

2. Disconnect and remove the battery. Use the

battery removal procedure described in either 1. TRACTION MOTOR 6. WHEEL NUT
the Operating Manual or the section Peri- 2. CAPSCREW 7. WHEEL
odic Maintenance 8000 SRM 970 or Periodic 3. LOCKWASHER 8. DRIVE UNIT
4. CAPSCREW 9. ARTICULATING
Maintenance 8000 SRM 1197.
5. LOCKWASHER AXLE
3. Remove the electrical compartment cover for ac-
Figure 18. Drive Unit Assembly
cess to the traction motor controller. Remove the
capscrews retaining the cover to the frame. See
Figure 18.

WARNING
The capacitor in the traction motor controller
can hold an electrical charge after the battery
is disconnected. To prevent electrical shock or
injury, discharge the capacitor before inspect-
ing or repairing any component. Wear safety
glasses. Make certain the battery has been dis-
connected.

4. Discharge the capacitor in the controller by

connecting a 200-ohm, 2-watt resistor across
the controller’s a load across the B+ and B
terminals of the motor controller for 10 seconds.
Remove the resistor after discharging the capac-
itor See Figure 19.

5. Open the drive unit compartment door and fas- 1. POSITIVE CONNECTION (B+)
2. NEGATIVE CONNECTION (B )
ten the door so that it is fully open. Put a pan 3. INSULATED JUMPER WIRES
under the MDU drain plug and remove the plug. 4. 200-OHM, 2-WATT RESISTOR
After the oil has completely drained, reinstall the
drain plug. Tighten to 22 N•m (16 lbf ft). Figure 19. Discharging the Capacitors

18
630 SRM 1022 GK Master Drive Unit

1. Use a crane and chain or sling with appropri-

WARNING ate capacity to lift the frame. Lift the frame for
The motor is heavy. Use appropriate lifting enough clearance to slide the MDU under the
equipment to avoid personal injury. frame or steer axle. Temporarily install blocks
under the frame to prevent lowering. Lay the
6. Remove the capscrews and lockwashers that fas- MDU under the drive chassis.
ten the traction motor to the adapter ring on the
MDU. Carefully lift and sit the motor out of the 2. Move the MDU into approximate alignment un-
way. Use rope to fasten the motor to prevent it der the frame or axle plate.
from falling.
3. Align both the MDU with the screw holes and
the steer gear with the axle pilot hole. Carefully
WARNING raise the frame and remove the blocks. Lower the
There are close clearances between the MDU, frame and align the capscrew holes in the large
drive chassis, and base arm that can cause se- ball bearing, adapter ring, and the frame or axle
rious injury. NEVER put hands, arms, head, plate.
or legs between these parts unless there are
blocks in place to prevent movement. If the 4. Install the capscrews and lockwashers that fas-
MDU falls, it can cause an injury. Support the ten the adapter ring and MDU to the frame or
MDU vertically to prevent it from falling. axle plate. Use cross pattern to tighten the cap-
screws to the appropriate torque. Make sure the
7. Place a sling under the lift truck frame on the large ball bearing and adapter ring are in the cor-
mast side of the MDU. Make sure the lifting de- rect position around the complete circumference.
vice and sling have the ability to lift approxi-
mately 3541 kg (7800 lb). ASSEMBLE
8. Remove capscrews and lockwashers that fasten
the adapter ring and MDU to the articulating CAUTION
axle or truck frame. The MDU is only allowed to be lifted with
soft ropes or belts, never with steel cables or
WARNING chains. Care must be taken during transport
The MDU is heavy. It can weigh approximately to avoid shocks. This is especially important
52 kg (114.6 lb). Use appropriate lifting equip- pertaining to wheel bolts, the electric motor,
ment to avoid personal injury. and accessories.

9. Hold the MDU and raise the truck frame so that The corrosion protection can only be removed
the MDU is free. Move the MDU from under the from the connecting points using a suitable
lift truck. Lower the lift truck frame on blocks. cleaner. Never use benzene, solvents, or other
combustible substances for cleaning. Use
INSTALL only nontoxic, noncombustible, and commer-
cially permissible cleaning agents. Wear safety
gloves and goggles!
WARNING
The lift truck and components are heavy. DO NOT drain cleaners into the soil. DO NOT al-
Be sure that all lifting devices (hoists, ca- low cleaners to contact rubber parts, electrical con-
bles, chains, slings, etc.) are suitable and of nections of accessories, or the motor ventilation.
adequate capacity to lift the lift truck or com-
ponent to avoid personal injury.

19
GK Master Drive Unit 630 SRM 1022

Mounting Electric Motor DISASSEMBLE

1. Apply a thin coat of lubrication grease onto the To disassemble, reverse the assembly process ex-
splined shaft-hub connection. plained in previous section.

2. Assemble the electric motor into the centering

seat of the steering bearing and cautiously join
it with the splined hub connection of the drive
pinion.

3. Turn the hole pattern of the steering bearing so

that it is aligned with the electric motor.

4. Install the six capscrews and lockwashers that

fasten the electric motor and tighten to appropri-
ate torque.

Pivoted Connection - Geared Steering

1. Make sure that the gear rim is clean and pay
attention that no foreign substances or cleaning
agents get through the threaded boreholes of the
connecting structure into the transmission inte-
rior. See Figure 20.

2. Align the gear rim and bolt holes with the

threaded boreholes of the connecting structure.
Install the steering bearing on the correct side
and turn it so the bolt holes are aligned with the
hole pattern of the gear rim and the housing.

3. Install capscrews to 34 N•m (25 lbf ft) to fasten

the steering bearing and the gear rim onto the
connecting structure.
1. BOREHOLES 3. STEERING
NOTE: Use Loctite® adhesive as needed. During dis- 2. GEAR RIM BEARING
assembly and later reuse of the screws, the adhesive 4. CAPSCREWS
remaining on the thread must be removed and new
screws must be used. Figure 20. Geared Steering

The fixing bolts should be checked at fixed inter-

vals or operating hours, especially in case of high
breakdown torque load or suspended axial load.

20
630 SRM 1022 GK Master Drive Unit

TROUBLESHOOTING

PROBLEM POSSIBLE CAUSE PROCEDURE OR ACTION

Lift truck will not move. Traction motor not operating. Repair or replace traction motor.

Damaged gears or bearings. Replace drive unit.

Master drive unit makes Insufficient lubricant or incorrect lu- Lubricate as needed.
noise. bricant.

Dry, damaged, or incorrect bearings. Lubricate as needed.

Worn or damaged gears. Replace drive unit.

Oil leaks at the wheel shaft. Shaft seal incorrectly mounted or Replace drive unit.
damaged.

Surface of axle shaft damaged. Replace drive unit.

Oil leaks at the filler plug or Dirt between sealing ring and hous- Clean sealing ring and housing.
drain plug. ing.

Plugs not tightened to specified Tighten to appropriate torque.

torque.

Oil leaks in motor compart- Too much oil in MDU. Drain excess oil.
ment.

Breather defective. Clean or replace breather.

Trunnion bearing difficult to Centering ring separated, allowing Torque capscrews holding centering
turn, binds, or exceeds max- dirt to penetrate into bearing. ring to MDU.
imum clearance.

Cage segments are damaged. Replace trunnion bearing.

Deformation of the balls or ball Replace trunnion bearing.

races.

Bearing not properly lubricated. Replace trunnion bearing.

21
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 TECHNICAL PUBLICATIONS

630 SRM 1022 11/06 (10/06)(8/04)(9/03) Printed in U.S.A.