This document provides instructions for disassembly and assembly of a steering unit. It details removing components such as the end cover, gearwheel set, cardan shaft, distributor plate and O-rings. It also describes disassembling the pressure relief valve. The assembly section outlines installing parts like the spool, sleeve, cross pin, bearings, seals and O-rings using various tools. Precise positions and torque specifications are given for correct reassembly.

1. CONTENTS
SECTION 1 GENERAL
Group 1 Safety Hints 1-1
Group 2 Specifications 1-5
Group 3 Periodic Replacement 1-13
SECTION 2 REMOVAL AND INSTALLATION OF UNIT
Group 1 Major Components 2-1
Group 2 Removal and Installation of Unit 2-2
SECTION 3 POWER TRAIN SYSTEM
Group 1 Structure and Operation 3-1
Group 2 Troubleshooting 3-16
Group 3 Tests and Adjustments 3-20
Group 4 Disassembly and Assembly 3-22
SECTION 4 BRAKE SYSTEM
Group 1 Structure and Function 4-1
Group 2 Operational Checks and Troubleshooting 4-9
Group 3 Tests and Adjustments 4-12
SECTION 5 STEERING SYSTEM
Group 1 Structure and Function 5-1
Group 2 Operational Checks and Troubleshooting 5-11
Group 3 Disassembly and Assembly 5-13
SECTION 6 HYDRAULIC SYSTEM
Group 1 Structure and Function 6-1
Group 2 Operational Checks and Troubleshooting 6-16
Group 3 Disassembly and Assembly 6-20
SECTION 7 ELECTRICAL SYSTEM
Group 1 Component Location 7-1
Group 2 Electrical Circuit 7-2
Group 3 Component Specification 7-11
Group 4 Connector Destination 7-12
Group 5 Troubleshooting 7-14

2. SECTION 8 MAST
Group 1 Structure 8-1
Group 2 Operational Checks and Troubleshooting 8-4
Group 3 Adjustment 8-7
Group 4 Removal and Installation 8-10

3. 5-13
GROUP 3 DISASSEMBLY AND ASSEMBLY
1. STEERING UNIT
STRUCTURE1)
3
4
14
6
21
1
5
8
16
7
10
19
13
10
17
9
15
20
18
22
23
11
2
12
14
24
26
25
D353SE05
1 Dust seal
2 Retaining ring
3 Cap seal
4 Thrust bearing
5 Ball
6 Pin
7 Spacer
8 Center spring
9 Washer
10 O-ring
11 O-ring seal
12 Rolled screw
13 Gerotor set
14 Bearing race
15 Bore screw
16 Drive shaft
17 End cap
18 Bushing
19 Plate
20 Cap screw
21 Housing
22 Spool
23 Sleeve
24 Relief valve
25 Check valve
26 Suction valve

4. TOOLS
Holding tool.
5-14
2)
(1)
Assembly tool for O-ring and kin-ring.(2)
Assembly tool for lip seal.(3)
Assembly tool for cardan shaft.(4)
5-69(1)
5-69(2)
5-69(3)
5-69(4)

5. 5-15
Assembly tool for dust seal.(5)
Torque wrench 0~7.1kgf・m
(0~54.4lbf・ft)
13mm socket spanner
6, 8mm and 12mm hexagon sockets
12mm screwdriver
2mm screwdriver
13mm ring spanner
6, 8 and 12mm hexagon socket spanners
Plastic hammer
Tweezers
(6)
5-70(1)
5-70(2)
D353SE23
TIGHTENING TORQUE
L : Left port
R : Right port
T : Tank
P : Pump
3)
Port
L
R
T
P
Mounting bolt
Size
3/4 UNF - 16
3/4 UNF - 16
3/4 UNF - 16
3/4 UNF - 16
M10×1.5
Torque [kgf・m(lbf・ft)]
13 (94)
13 (94)
13 (94)
13 (94)
5.0 ±1.0 (36±7.2)

6. 5-16
DISASSEMBLY
Disassemble steering column from
steering unit and place the steering unit in
the holding tool.
Screw out the screws in the end cover(6-
off plus one special screw).
4)
(1)
Remove the end cover, sideways.(2)
Lift the gearwheel set(With spacer if fitted)
off the unit.
Take out the two O-rings.
(3)
Remove cardan shaft.(4)
5-72(1)
5-72(2)
5-72(3)
5-72(4)

7. 5-17
Remove distributor plate.(5)
Screw out the threaded bush over the
check valve.
(6)
Remove O-ring.(7)
Shake out the check valve ball and suction
valve pins and balls.
(8)
5-73(1)
5-73(2)
5-73(3)
D353SE09

8. 5-18
Take ring, bearing races and thrust
bearing from sleeve and spool. The outer
(Thin) bearing race can sometimes "stick"
in the housing, therefore check that it has
come out.
(10)
Press out the cross pin. Use the special
screw from the end cover.
(11)
A small mark has been made with a
pumice stone on both spool and sleeve
close to one of the slots for the neutral
position springs(See drawing).
If the mark is not visible, remember to
leave a mark of your own on sleeve and
spool before the neutral position springs
are disassembled.
※
Take care to keep the cross pin in the
sleeve and spool horizontal. The pin can
be seen through the open end of the
spool. Press the spool inwards and the
sleeve, ring, bearing races and thrust
bearing will be pushed out of the housing
together.
(9)
5-73(4)
5-74(1)
5-74(2)
5-74(3)

9. 5-19
Press the neutral position springs out of
their slots in the spool.
(13)
Remove dust seal and O-ring.(14)
Disassembling the pressure relief valve
Screw out the plug using an 8mm hexagon
socket spanner.
Remove seal washers.
(14)
Carefully press the spool out of the sleeve.(12)
5-74(4)
5-75(1)
5-75(2)
D353SE10

10. 5-20
Unscrew the setting screw using an 8mm
hexagon socket spanner.
(15)
Shake out spring and piston. The valve
seat is bonded into the housing and cannot
be removed.
(16)
The pressure relief valve is now disassem-
bled.
(17)
D353SE11
D353SE12
D353SE13

11. 5-21
ASSEMBLY
Assemble spool and sleeve.
When assembling spool and sleeve only
one of two possible ways of positioning
the spring slots is correct. There are
three slots in the spool and three holes in
the sleeve in the end of the spool / sleeve
opposite to the end with spring slots.
Place the slots and holes opposite each
other so that parts of the holes in the
sleeve are visible through the slots in the
spool.
5)
(1)
※
Place the two flat neutral position springs
in the slot.
Place the curved springs between the flat
ones and press them into place (see
assembly pattern).
(2)
Line up the spring set.(3)
5-76(1)
5-76(2)
5-76(4)
Guide the spool into the sleeve. Make
sure that spool and sleeve are placed
correctly in relation to each other.
(4)
5-77(1)

12. 5-22
Press the springs together and push the
neutral position springs into place in the
sleeve.
(5)
Line up the springs and center them.(6)
Guide the ring down over the sleeve.
The ring should be able to rotate free of
the springs.
(7)
※
5-77(2)
5-77(3)
5-77(4)
Fit the cross pin into the spool / sleeve.(8)
5-78(1)

13. 5-23
5
4
3
2
1
Fit bearing races and needle bearing as
shown on below drawing.
(9)
Assembly pattern for standard bearings
1 Outer bearing race
2 Thrust bearing
3 Inner bearing race
4 Spool
5 Sleeve
※
Installation instruction for O-ring
Turn the steering unit until the bore is
horizontal. Guide the outer part of the
assembly tool into the bore for the spool /
sleeve.
(10)
5-78(2)
5-78(3)
5-78(4)

14. 5-24
Grease O-ring with hydraulic oil and place
them on the tool.
(11)
Hold the outer part of the assembly tool in
the bottom of the steering unit housing
and guide the inner part of the tool right to
the bottom.
(12)
Press and turn the O-ring into position in
the housing.
(13)
5-79(1)
5-79(2)
5-79(3)
5-79(4)

15. 5-25
Installation instructions for lip seal
Lubricate the lip seal with hydraulic oil and
place it on the assembly tool.
(15)
Guide the assembly tool right to the
bottom.
(16)
Draw the inner and outer parts of the
assembly tool out of the steering unit bore,
leaving the guide from the inner part in the
bore.
(14)
5-80(1)
5-80(2)
5-80(3)
5-80(4)

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17. 5-26
The spool set will push out the assembly
tool guide. The O-ring are now in
position.
(19)
Turn the steering unit until the bore is
vertical again. Put the check valve ball
into the hole indicated by the arrow.
(20)
Press and turn the lip seal into place in the
housing.
(17)
With a light turning movement, guide the
spool and sleeve into the bore.
Fit the spool set holding the cross pin
horizontal.
(18)
※
5-81(1)
5-81(2)
5-81(3)
5-81(4)

18. 5-27
Place the distributor plate so that the
channel holes match the holes in the
housing.
(23)
Guide the cardan shaft down into the bore
so that the slot is parallel with the
connection flange.
(24)
Screw the threaded bush lightly into the
check valve bore. The top of the bush
must lie just below the surface of the
housing.
(21)
Grease the O-ring with mineral oil approx.
viscosity 500 cSt at 20°C.
(22)
5-82(1)
5-82(2)
5-82(3)
5-82(4)