Description

The L70D features hydrostatic articulated frame steering consisting of one of the two variable
displacement hydraulic pumps connected in parallel, central valve, steering valve and two
cylinders. The outlet ports of the steering valve are connected to the plus and minus sides of the
steering cylinders.
Two variable hydraulic pumps (P1 and P2) are connected in parallel and common to the brake
system, servo system and working hydraulics. Pump 1, located closest to the transmission, also
supplies the steering system with fluid and gives it priority over the brake system, servo system,
and working hydraulics.
The fluid is drawn from the hydraulic fluid tank.
The purpose of the central valve is to distribute hydraulic fluid to the working hydraulics and the
brake, steering and servo systems.
For a description of the central valve, see [Invalid linktarget].

Figure 1
Steering system
1. Steering valve
2. Hydraulic oil tank
3. Steering cylinders
4. Hydraulic fluid pumps P1 and P2.
5. Central valve
6. Hydraulic diagram, steering
7.
8.

9. Figure 1
Hydraulic diagram, steering system
A Hydraulic oil
pump
B Hydraulic fluid
pump, cooling
fan
motor/brakes
C Hydraulic oil
tank
D Central valve
E Return fluid
block
H Steering valve
II Steering
cylinders
J Secondary
steering
K CDC valve
QQ Return oil filter

Specifications, general
Type Hydrostatic
Steering angle ± 40°
Number of 3.7 turns
steering wheel
turns, total
Specifications, general
Hydraulic pump (common to
other hydraulic equipment)
Type Nine-cylinder
axial piston
pump, variable
displacement
Max. steering 21.0 ±0.5 MPa
pressure (210 ±5 bar)
(low idling) (3045 ±72.5
psi)
Hold (stand-by) 2.8 ±0.4 MPa
pressure (28 ±4 bar)
(406 ±58 psi)
Steering valve
Type "Closed centre"
Shock valves
Number of 2 pcs
valves
Shock valve, 28 ±0.5 MPa
opening (280 ±5 bar)
pressure, idling (4060 72.5 psi)
Steering
cylinder
Type Double-acting
Weight 14 kg (31 lbs)
Inside diameter 63 mm (2.48 in)
Piston rod 40 mm (1.57 in)
diameter
Stroke 370 mm (14.57
in)

Specifications, tightening torques

Steering Tightening torques
system
Pin retainers - (M8) 24 Nm 2.4 kgf m (5.3
steering (17.7 lbf ft) lbs)
cylinders (M12) 85 Nm 8.5 kgf m (18.7
(62.7 lbf ft) lbs)
Connecting rod 200 Nm 20 kgf m (44.0
- piston (147.5 lbf ft) lbs)
Connecting rod 200 Nm 20 kgf m (44.0
guide - cylinder (147.5 lbf ft) lbs)
jacket
Steering valve 30–35 Nm 3.0–3.5 kgf m
cover (22.1–25.8 lbf (6.6–7.7 lbs)
ft)
Hydraulic pump, description
The pump is a nine-cylinder axial piston pump with variable flow.
As the drive shaft (9) rotates, the cylinder block (6), pistons (7) and swash plate (8) also rotate
with it.
The stroke of the pistons is then dependent on the angle of the swash plate (10).
The angle is determined by the difference between the pressure from the control piston and the
spring.
When the piston is in its innermost position and on its way out it passes a bow-shaped groove (4)
in the distribution plate (5). The fluid is sucked (or more accurately, forced by atmospheric
pressure) from the inlet port (3) via the inlet groove (4) into the cylinder.
When the piston has passed its outermost position and is on its way back into the cylinder, the
fluid is forced out through the outlet groove (2) and on to the outlet port (1).

Figure 1
Hydraulic pump
Outlet port
Outlet groove in distribution plate
Inlet port
Inlet groove in distribution plate
Distribution plate
Cylinder block
Piston
Swash plate
Drive shaft
Yoke
Pressure/flow compensator
The purpose of the flow compensator is to control the pump via the control piston (8) and spring
(7) at all times so that it will always supply a flow of fluid, the pressure drop of which in the system
corresponds to a preset pressure difference between the pump outlet and the load-sensing port
on the governor.
The purpose of the pressure compensator is to control the pump via the control piston (8) and
spring (7) so that the maximum pressure for the working hydraulics is limited.

Figure 2
Hydraulic pumps 1 and 2
A Pump 1
B Pump 2
1 Bearing 6 Drive shaft
2 Distribution 7 Spring
plate
3 Pump unit 8 Control piston
(With cylinder
block and
piston)
4 Housing 9 Flow
compensator
(hold/standby
pressure)
5 Yoke 10 Pressure
compensator
(Main pressure)

Steering cylinder, cutaway view

Figure 1
Steering cylinder
1. Piston seal
2. Bakelite bushings
3. O-ring with back-up ring
4. O-ring
5. Seal
6. Scraper seal

Steering cylinder, reconditioning

Op nbr 64506
999 3725 Draw bolt
999 3722 Support
999 3712 Socket
999 3714 Draw bolt
999 3717 Speed nut
999 3686 Plate
11 667 060 Plate
11 667 050 Plate

Hook spanner diam. 76 mm (2.99 in)

Removing
1. Steer the machine at full lock from the side on which the steering cylinder is to be
reconditioned.
Remove the cover plate between the cab and frame.
NOTE!
Use a long 12 mm (0.47 in) socket with max. 17 mm (0.67 in) outside diameter on the
rear steering cylinder pin.
 Figure 1
Removing the rear pin
2. Remove the retaining ring from the front steering cylinder pin.
Thoroughly clean that part of the pin protruding from the piston rod fork.
Remove the pin using 999 3725 draw bolt and 999 3722 support.

Figure 2
Removing the front pin
3. Remove the steering cylinder hose connections.
Compress the steering cylinder. Drain the fluid into a suitable receptacle.
Plug all connections.
4. Remove the retaining ring from the rear steering cylinder pin. Withdraw the pin, using
999 3725 draw bolt and 999 3722 support. Twist the steering cylinder and lift it out of the
frame.

Figure 3
Removing the rear pin
5. Clamp the steering cylinder in a vice. Use soft protective jaws to avoid deforming the
cylinder.
6. Remove the piston rod guide using a hook spanner diam. 76 mm and withdraw the piston
rod from the cylinder. Collect the oil that runs out of the cylinder in a suitable receptacle.
 Figure 4
Removing the piston rod guide
7. Clamp the piston rod in a vice, drive out the lock pin and undo the nut.

Figure 5
Driving out the lock pin
8. Remove piston and piston rod guide. Clean and inspect for damage and wear. Change
seals.
9. Remove the retaining rings and withdraw the link bearing with socket 999 3712, draw bolt
999 3714, nut 999 3717 and drift plate 11 667 060.
Assembling
10. Fit the link bearing and retaining rings, using socket 999 3712, draw bolt 999 3714, nut
999 3717 and drift plate 11 667 060.

Figure 6
Fitting link bearing and retaining rings
11. Fit the piston rod guide on the piston rod and fit the piston.
Tighten the nut.
 Tightening torque: 200 ±25 Nm (148 ±18 lbf ft)
Secure the piston with spring pins.
NOTE!
If the existing piston - piston rod hole does not fall within the prescribed torque, the piston
must not be turned back. A new hole should be drilled for securing the piston with spring
pins.
12. Fit the piston rod in the cylinder and tighten the piston rod guide.
Tightening torque: 200 ±25 Nm (148 ±18 lbf ft)
Changing the steering piston rod link bearing in the front frame
13. Withdraw the link bearing, using draw bolt 999 3714, socket 999 3712, drift plate  11 667
050 and speed nut 999 3717.

Figure 7
Changing the link bearing
14. Pull in the new link bearing using the same tools as when withdrawing the old one.
NOTE!
The bearing must be centred in the frame.
Installing
15. Lift the steering cylinder into the frame, fit the link bearing seals and line up the cylinder
with the hole in the frame.
16. Fit the pin. Use plate 999 3686 and draw bolts 999 3714, 999 3725.
 Figure 8
Fitting the rear pin
17. Pull out the piston rod and line it up with the hole in the frame. Fit the shims.
18. Insert the locating screw in the fork and fit the pin in place.
NOTE!
Fitting will be easier if the pin is chilled.

Figure 9
Fitting the front pin
19. Fit the grease nipple in the pin.
20. Attach the hydraulic hoses to the steering cylinder. Attach the lubrication pipe to the rear
steering cylinder pin. Lubricate the pins.
21. Start the engine and drive the machine back and forth a few times, steering at full left and
full right lock in order to bleed the steering cylinder.
22. Check that no leakage occurs and refit the cover plate.

Steering pressure and holding pressure, checking and

adjusting
Op nbr 64515
11 666 020 Pressure gauge 0 –25 MPa (0–3625 psi)
11 666 037 Hose

The following applies when

checking:
Temperature: Normal
operating
temperature.
[T1]
Engine speed: Low idle
speed
Steering 21.0 ±0.5 MPa
pressure: (3045 ±72.5
psi)
Holding (stand- 2.8 ±0.4 MPa
by) pressure: (406 ±58 psi)
[T1]Achieved in about 15 minutes on a haulage run.

Do not work under the machine when the engine is running.

Checking the steering pressure
1. Connect the frame joint lock.
 Figure 1

2. Connect a pressure gauge to the pressure outlet on the steering valve.

Figure 2
Checking the steering pressure
1. Hose 11 666 037 with pressure gauge 11 666 020
3. Start the engine and let it run at low idle.
4. Steer to frame joint locking and check the maximum steering pressure.
Adjusting
5. Any necessary adjustment should be carried out on the central valve.
 Figure 3
Central valve
2. Adjusting steering pressure
Checking holding pressure
6. Connect a pressure gauge to the pressure outlet on the control valve.
7. Start the engine and let it run at low idle.

Figure 4
Checking hold (stand-by) pressure
1. Hose 11 666 037 with pressure gauge 11 666 020
8. Read off the holding pressure.
NOTE!
Use pressure gauge 0-25 MPa (0-3625 ps). If the brake system starts charging, the
pressure in the outlet will rise to approx. 16.5 MPa (2392.5 psi). Wait then while the
pressure in the brake system builds up, following which the holding pressure can be
checked (see Section 5 for further information).
Adjusting
9. Carry out adjustment with the adjusting screws on the relevant pump’s flow compensator,
as follows.

Figure 5
Hydraulic pump
3. Adjusting holding pressure
10. Unscrew the protective caps from the adjusting screws. Slacken the lock nuts and back
off both adjusting screws about one turn so that a lower pressure than the specified
holding pressure is obtained.
11. Observe the pressure gauge and adjust to the correct pressure on the first pump. Lock
the adjusting screw.
Adjust the other pump until the pressure starts to increase. Then adjust it further so that
the pressure drops to that attained by the first pump. Lock the adjusting screw.
Steering valve, description
The steering valve is of non-reaction type with closed centre. "400" in the designation indicate
that it delivers 400 cm3 (24.4 in3) of oil per steering wheel turn. The steering valve has a load-
sensing outlet (LS) from which a steering pressure is obtained for the central valve’s LSS
connection. This steering pressure goes from the central valve LS connection to the flow
compensator on pumps 1 and 2.
Function
When the steering wheel is held stationary, the steering valve is in the neutral position and
holding pressure (stand-by pressure) is obtained from pump P1 by means of the flow
compensator. P1 is angled down and supplies no fluid to the steering system. P2 is also angled
down and supplies no fluid to the brake and servo systems nor to the working hydraulics. P2 also
maintains holding pressure which is as high as P1.

Figure 1
Steering valve
Punched marking, week/year, e.g. 416 (week 41 year 1996)
When the steering wheel is turned in any direction, it causes turning of the inner and outer spools.
When this turning amounts to 1.5°, the ducts to the metering unit (rotor and rotor ring) and the
load-sensing port (LS) begin to open.
At 6° turning the channels to the metering unit and load-sensing port are fully open. Turning of the
inner and outer spools is limited to ± 8–9°.
Figure 2
Steering valve
1 Valve housing 13 Distribution
plate
2 Inner valve 14 Rotor and rotor
spool ring
3 Outer valve 15 Cover
spool
4 Seal 16 Screw with
guide pin
5 Ball (non-return 17 Screw
valve)
6 O-ring 18 Washer
7 Sealing ring 19 O-ring
8 Thrust bearing 20 Distribution
plate
9 Ring (retainer) 21 O-ring
10 Cross-pin 22 Type plate
11 Leaf springs 23 Blind rivet
12 Rotor shaft A Seal
Steering
Neutral position
The steering valve (7) is in the neutral position. The LS-line (8) then has only increased tank
pressure. Pressure builds up in the outlet line (10) and pressure line (11). The pressure goes past
the pressure reducing spool (5). Approx. 0.3 MPa (43.5 psi) is required to overcome the spring
force and the spool closes. Owing to the permitted internal leakage across the slide (5), the
pressure arriving at the steering valve (7) will be much higher, although not the same as holding
pressure.
NOTE!
The holding pressure cannot be measured on the steering valve’s pressure check connection,
see [Invalid linktarget].
The pressure compensator (2) for working hydraulics is held in its lower position by the spring
(13). The spring (15) balances the flow compensator valve spool (14) so that fluid can flow out to
the control piston (16), which reduces the angle of the swash plate. The spring (17) acts on the
swash plate in the opposite direction to the control piston but with less force. The pressure from
the pump is regulated to a pressure which is dependent on the force of the spring (15) plus the
pressure in the LS-line (8), which in neutral is equal to the increased pressure in the tank (0.6
MPa (87 psi)). A pressure difference is thus created between the lines (8 and 10) which is the
same as the holding pressure. Adjustment of the holding pressure is performed on the adjusting
screw (18).
Figure 3
Steering system
1 Flow 11 Pressure line
compensator
2 Pressure 12 Pressure
compensator, compensator
working spool
hydraulics
3 Pump 1 13 Spring
4 Central valve, 14 Flow
simplified compensator
spool
5 Pilot-controlled 15 Spring (2)
pressure
reducing spool
6 Pressure- 16 Control piston
reducing valve
for max.
steering
pressure
7 Steering valve 17 Spring
8 Load-sensing 18 Adjusting
line LS screw, holding
pressure
9 Pressure back- 19 Adjusting
up valve screw, max.
working
hydraulics
pressure
10 Outlet line
Green Return, no
pressure
Violet Trapped fluid

Orange Hold (stand-by)

pressure
Steering
The LS line obtains communication with one of the motor ports (the pressure port) on the steering
valve (7). The LS pressure goes in at the rear of the priority valve and, together with the spring
force, presses the spool down and redirects the fluid to the steering system. The steering system
thus takes priority over the brake, servo and working hydraulics systems.
Simultaneously, the LS pressure goes in at the rear of the pressure-reducing spool (5) and,
together with the spring force, presses it down and opens the connection to the steering valve.
The LS pressure then continues to the top of the flow compensator spool (14) and, together with
the spring force, presses it to a balanced position against the pressure in the outlet line (10). By
draining the fluid to the control piston (16), the flow compensator spool controls the angle of the
pump’s swash plate so that the pump delivers a volume of fluid that is proportional to steering
movement and steering speed.
The increase in fluid flow is balanced via the balancer piston and spring (17), which act on the
swash plate in the opposite direction to the control piston.
Figure 4
Steering, normal
3 Pump 1 Red Pressurized
fluid
5 Pilot-controlled Blue Increased
pressure return pressure
reducing spool
7 Steering valve Green Return, no
pressure
10 Outlet line
14 Flow
compensator
spool
17 Spring
Steering against lock (end) position
When the pressure in the LS line rises to maximum steering pressure, the pressure-limiting valve
(6) opens. When this happens the pressure-reducing spool (5) closes and cuts off the flow up to
the steering valve (7). The pump pressure opens the priority valve.
The LS pressure also goes in to the top of the flow compensator spool (14). The output pump
pressure acts on the underside of the spool (14) and overcomes the LS pressure plus spring
force owing to the difference in pressure between the output pump pressure and the LS pressure.
The fluid is directed to the control piston (16). The angle of the swash plate is reduced and with it
the flow, but maximum steering pressure is retained.
Adjustment of maximum steering pressure is carried out on the pressure- limiting valve (6).
Figure 5
Steering against lock (end) position
3 Pump 1 Red Pressurized
fluid
5 Pilot-controlled Pink LS pressure
pressure
reducing spool
6 Pressure- Blue Increased
reducing valve return pressure
for max.
steering
pressure
7 Steering valve Green Return, no
pressure
14 Flow
compensator
spool
16 Control piston

Steering valve, reconditioning

Op nbr 64581
6999 007 Handle
6999 025 Plate
6999 034 Plate
Dismantling
1. Mark the steering valve parts in relation to each other in order to facilitate assembling.
Secure the steering valve in a vice. Use soft protective jaws.
Remove the cover.

Figure 1

2. Remove the metering unit, rotor shaft and distribution plate.

Remove the O-ring.

Figure 2

3. Remove the steering valve from the vice and remove the ball.
 Figure 3
Removing ball
4. Remove the inner and outer spools.

Figure 4

5. Remove the axial disc, needle bearing, bearing race and the ring.

Figure 5

6. Remove the cross-pin.

 7. Remove the outer and inner seals.
8. Carefully press the inner spool out of the outer one.
Remove the leaf springs.
Clean and check all parts with regards to wear and any damage.
Change worn and damaged parts.
Change all seals and washers.
Remove any minor burrs using a fine-grain whetstone.

On no account should lapping paste be used.

Assembling

Lubricate all parts with hydraulic fluid before assembly.

10. Fit the outer seal ring.

Figure 6
Installing seal ring
4. 6999 007
5. 6999 025
6. 6999 034
10. Secure the valve housing in a vice. Use soft protective jaws.
11. Place the assembled seal on the drift plate and press the seal into the housing.
NOTE!
Location of the seal. O-ring  
 Figure 7
Fitting the seal
7. 6999 007
8. 6999 025
9. 6999 034
12. Assemble the inner and outer spools so that the leaf spring grooves line up and the three
T-shaped grooves "A" in the inner spool line up with the small holes "E" in the outer
spool. Check that the punch marks on the top of the spools line up.

Figure 8
Assembling the outer and inner spools
1. T-shaped groove (inner spool)
2. Hole (outer spool)
3. Punch marks
13. Fit the leaf springs. Make sure that they are positioned correctly.

Figure 9
Position of leaf springs
14. Fit the axial disc, needle bearing, bearing race and the ring on the inner and outer spools.
NOTE!
Fit the bearing race with the chamfer facing the inner spool.
 Figure 10
Positioning the axial disc, needle bearing, bearing race and ring on the valve spool
10. Ring
11. Bearing race
12. Needle bearing
13. Axial disc
15. Fit the cross-pin on the inner and outer spools.
16. Fit the inner and outer spools in the valve housing. Rotate the inner and outer spools so
that their cross-pin is at an angle of 90º to plane A.

If the inner and outer spools are not fitted correctly in relation to each other the steering
valve could act as a motor and the machine will then steer uncontrollably the first time it
is steered.

Figure 11
Inner and outer spools and position of cross-pin in valve housing
17. Fit the O-ring.
Fit the distribution plate so that the channel holes line up with corresponding holes in the
valve housing.
 Figure 12

14. Distribution plate on valve housing

18. Fit the rotor shaft.
Fit the O-ring and metering unit so that the tops of two rotor teeth are parallel with plane
"A".
NOTE!
Make sure that the marks made earlier are in line with each other.

Figure 13

4. Position of metering unit relative to the valve housing

19. Fit the cover (make sure that the marks made earlier are in line with each other) and the
bolts.
Fit the ball and the bolt fitted with locking pin.
Tighten the screws crosswise.
Tightening torque: 30–35 Nm (4350–5075 psi)
 Figure 14
Fitting the ball in the valve housing

Hydraulic diagram, steering, incl. CDC and secondary

steering
A Hydraulic oil
pump
B Hydraulic fluid
pump, cooling
fan
motor/brakes
C Hydraulic oil
tank
D Central valve
E Return fluid
block
H Steering valve
II Steering
cylinders
J Secondary
steering
K CDC valve
QQ Return oil filter
AA Motor,
secondary
steering
AB Valve,
secondary
steering

Figure 1
Hydraulic diagram, steering system

Secondary steering, description

The system incorporates an electrically operated hydraulic pump, MO601, which is controlled by
the V-ECU via RE601.
Figure 1
Secondary steering pump
1. MO601
2. RE601
The I-ECU receives signals from test switch SW601, two sensors, SE601 and SE602, and the
machine’s travel speed sensor, SE403.
The flow and differential pressure sensor SE601 senses the flow from the primary steering pump
as well as the difference between the main pressure and the LS-pressure.
Pressure sensor SE602 senses the main pressure.

Figure 2
Flow and differential pressure sensor
1. SE601 Differential pressure sensor
2. SE602 Flow sensor
Before starting the engine
If test switch SW601, flow and differential pressure sensor SE601 or pressure sensor SE602 are
connected, the ECU will consider the equipment to be installed.
The V-ECU checks the sensor circuits. With the engine switched off and the ignition switch in the
drive position, the warning lamp for a primary steering system (1) fault or an open circuit in any of
the sensors circuits will start flashing.
While operating
If the flow and differential pressure sensor SE601 is activated, sensor closed, the secondary
steering pump will start if travel speed is above 5 km/h (3.1 mph).
The lamp indicating that the secondary steering pump has started (2) comes on and the pump
continues to run as long as the sensor remains closed.
In case of a primary steering system pressure loss, flow and differential pressure sensor SE601
and primary steering pressure sensor SE602 will close. This causes the secondary steering pump
to start if travel speed exceeds 5 km/h (3.1 mph). The indicator lamps (1 and 2) light up at the
same time as the central warning lamp starts to flash. In this case, the pump will continue to run
as long as travel speed exceeds 5 km/h (3.1 mph).

Figure 3
Instrument display unit
1. Warning lamp for primary steering system malfunction
2. Control light, indicates that secondary steering pump starts
Description, electrical functions
The V-ECU is supplied with current via fuse FU30, sensors SE601 and SE602. The I-ECU is
supplied with current via switch SW601, causing the warning lamp for a primary steering system
malfunction to come on.
The coil of relay RE601 now receives current from the V-ECU and is activated.
Secondary steering pump MO601, and the lamp indicating that the secondary steering pump has
started, are now supplied with current via relay RE601. The secondary steering pump starts and
the lamp comes on.
Function test
A functionality test of the secondary steering system is carried out with the machine stationary
and the engine switched off. The ignition switch should be in position 1.

Figure 4
SW601
When switch SW601 is depressed, the connection to the I-ECU is broken. Since sensors SE602
and SE601 are closed, the secondary steering pump will start and the lamp indicating this will
come on. The pump will continue to run as long as the switch is held down.
Secondary steering, electrical functions
Valve and function diagram, shows the situation before starting.
Prior to start, the peg (1) is held in the closed position by the spring (5) via the guide (4) and the
piston (2). At the same time, the guide keeps the pin (3) in, which results in sensor SE601 being
closed. Pressure sensor SE602 is also closed.
After starting, sensor SE602 is open as long as the steering pressure in connection PP exceeds
0.4 MPa (58 psi).
Sensor SE601 opens when the pin (3) is pressed outward toward SE601. The pin can be
actuated in two ways, by the flow or the pressure.
When the engine starts the peg (1) is pressed outward (toward SE601) and the PP – PU
connection opens. When the steering pump flow through connection PU exceeds 10 dm3/min
(2.6 US gal/min), the peg (1) is kept in the open position and thus the pin (3) is pushed outward
(toward SE601) via the piston (2). This function is independent of the pressure difference
between steering pressure and LS-pressure.
In connection PU there is either holding pressure or steering pressure. The pressure acts on the
piston (2) which is pressed against the guide (4), the pin (3) and the spring (5). The LS-pressure
enters the valve through the LS connection and attempts to press the piston in the opposite
direction. When the pressure difference between the steering pressure and the LS-pressure is
greater than 0.7 MPa (7 bar) (101.5 psi), the spring will be compressed and the pin opens sensor
SE601.
The LS-pressure also acts directly on the pin (3) and when the LS-pressure exceeds 7 MPa (70
bar) (1015 psi) the pin will compress the spring via the guide regardless of the steering pressure,
and the sensor will open. This occurs, for example, when steering reaches the full lock position
when steering pressure and LS-pressure attain the same value.
Secondary steering will engage if the travel speed of the machine exceeds 5 km/h (3.1 mph) and
the oil flow from the primary steering pump is below 10 dm3/min (2.6 US gal/min) at the same
time as the difference between steering pressure and LS-pressure is less than 0.7 MPa (7 bar)
(101.5 psi) (and LS pressure is below 7 MPa (70 bar) (1015 psi).
NOTE!
When LS pressure decreases, the need for differential pressure increases so that the secondary
steering system will not start.

During forced operation, the secondary steering system is disconnected and 3rd and 4th gears
are blocked.
Figure 5
Valve with flow and pressure diagram as well as function diagram
A. Steering valve
1. Peg
2. Piston
3. Pin
4. Steering
5. Spring
Secondary steering, wiring diagram

Figure 6
Wiring diagram, secondary steering system
Control lever SE603, checking input/output voltage
Op nbr 
–

Figure 1
Adjusting lever movement in direction B
1. Lower the armrest and remove the plastic cover and aluminium casing.
2. Turn the ignition switch to position 1 and engage lever steering with SW408.
3. The input power supply to steering lever SE603 and to MA601 should be approx. 24 V.
Take a reading on terminal 11 of electronic unit CU601 and terminal 1 of MA601.
4. Checking output power supply on the green/black lead. Take readings on terminal 3 of
electronic unit CU601.
15. Steering lever SE603 in neutral, approx. 12 V.
16. Move the steering lever to the right. The output voltage on the green/black lead
should gradually increase when the steering lever is moved to the end position.
The voltage at the end position should be 15 –18 V, depending on how steering
speed is adjusted with adjusting screw B, see [Invalid linktarget].
17. Move the steering lever to the left. The output voltage on the green/black lead
should then gradually decrease as the lever is moved to the end position. The
voltage at the end position should be 9 –6 V, depending on how steering speed
is adjusted with adjusting screw A, see [Invalid linktarget].
6. Check the chassis (earth) connection for MA601 and electronic unit CU601.
18. Turn the ignition switch to position 0.
19. Unplug the connector from MA601 on the control valve and use an ohmmeter to
check that a connection exists between the connector and chassis (earth)
terminal 31C (under the circuit board in the cab).
20. Also check that there is a connection between terminal 2 on electronic unit
CU601 and chassis (earth) terminal 31C.
21. Plug the connector into MA601.

Hydraulic diagram, steering, incl. CDC and secondary

steering
A Hydraulic oil
pump
B Hydraulic fluid
pump, cooling
fan
motor/brakes
C Hydraulic oil
tank
D Central valve
E Return fluid
block
H Steering valve
II Steering
cylinders
J Secondary
steering
K CDC valve
QQ Return oil filter
AA Motor,
secondary
steering
AB Valve,
secondary
steering
Figure 1
Hydraulic diagram, steering system

Lever steering (CDC), electrical functions

Functional description
The equipment is connected to the circuit board via the CDC connector.
With the ignition key in position 1, switch SW408 is supplied with current via fuse FU30.
When switch SW408 is activated and the armrest is lowered and closes SW407, current is sent to
the V-ECU on pins EA18 and EA4 (SW408 is spring-loaded). The coil of relay RE602 is then
supplied with current via V-ECU terminal EC6. Relay RE602 is activated and receives holding
current via the V-ECU.
Relay RE602 (30 - 87) also supplies current via electronic unit CU601 to switch SW410 for kick-
down, to CDC control valve MA601 and to the control lever for steering SE603.
When SE603 is activated, solenoid valve MA601 is supplied with current and the steering function
is engaged.
If the armrest is raised, SW407 interrupts the supply of current to V-ECU connection EA18. Relay
RE602 is deactivated by the V-ECU and interrupts the current supplied to SW410 for kick-down,
and lever steering is disengaged
If primary gear selector SW402 is moved to the forward or reverse position, the I-ECU will be
supplied with current on terminals P2.22 and P2.9. Relay RE602 is deactivated by the V-ECU
and lever steering is disengaged.
Example: Gear selector SW402 is moved to the F position (forward). The I-ECU is supplied with
current on terminal P2.22 via fuse FU14 and switch SW402 (GA1 - GA7). Relay RE602 is
deactivated by the V-ECU and lever steering is disengaged.
Lever steering must be engaged again by means of switch SW408, with the armrest lowered and
the gear selector in neutral. Otherwise, relay RE602 will not be supplied with current from the V-
ECU.
Electronic unit CU601
Smoother steering is obtained by means of the electronic unit in that the signal to MA601 is
damped when steering is started and finished. Damping (the ramp) duration is approx.
0.2 seconds.
Wiring diagram 17, Lever steering (CDC)
Figure 1
Wiring diagram, lever steering
Shifting, forward or reverse
See also [Invalid linktarget].
With the ignition key in position 1, switch SW408 is supplied with voltage via fuse FU30.
When switch SW408 is activated and the armrest is lowered and closes SW407, current is sent to
the V-ECU on pins EA18 and EA4 (SW408 is spring-loaded). The coil of relay RE602 is then
supplied with current via V-ECU terminal EC6. Relay RE602 is activated and receives holding
current via the V-ECU.
Relay RE602 (30 - 87) also supplies current via electronic unit CU601 to switch SW410 for kick-
down, to CDC control valve MA601 and to the control lever for steering SE603.
Forward shift
If switch SW409 is moved to position F (forward), the V-ECU will be supplied with current on
terminal EA32.
Reverse shift
If switch SW409 is moved to position R (reverse), the V-ECU will be supplied with current on
terminal EA5.
Kick-down
When either of the switches SW405 or SW410 is activated, V-ECU terminal EA19 will be supplied
with current. Also see description in Section 3.

Lever steering (CDC), general description

The equipment allows that steering, forward-reverse shifting, as well as engaging Kick-down can
be controlled through controls located in the left armrest.
When operating on a public road, the steering wheel must be used and lever steering must be
disengaged.

Figure 1
Armrest. CDC
SE603 Steering lever
SW408 Activation, CDC
SW409 Shifting,
forward -
reverse
SW410 Kick-down
SW407 Activation, CDC
in armrest
CU601 Electronic unit
The steering lever has two adjusting screws for adjusting steering speed. Electronic unit CU601 is
not adjustable but has fixed dampening to left and right.
The CDC steering control valve is located under the cab on the right-hand side.
The control valve is connected in parallel with the primary steering valve.
The shuttle valve for LS pressure is located by the primary steering valve.
The primary gear selector has priority in relation to the forward-reverse switch on the armrest.
This means that lever steering is disengaged if the gear selector is moved to the forward or
reverse positions.

Figure 2
Control valve, CDC
MA601
A control light on the centre instrument panel is lit when lever steering is engaged.

Figure 3

Control light, CDC

Function
Engaging, operating and disengaging
In order to engage lever steering, the armrest must first be lowered, which causes switch SW407
to close. Check that the primary gear selector is in neutral and, at the same time, turn its handle
to the desired gear position, normally 4 (automatic).
NOTE!
Fourth gear can be blocked via the service display unit when lever steering is in use.
Now engage lever steering with switch SW408 on the armrest. The indicator lamp on the centre
instrument panel should light up.
Move the steering lever to the desired steering position. The steering speed will increase
proportionally according to the lever deflection. Move the lever distinctly toward the neutral
position when the steering movement is to be interrupted.
Select forward, neutral and reverse gear with switch SW409. The Kick-down function is engaged
with switch SW410 on the side of the armrest.
CDC lever steering can be disengaged by lifting up the armrest or by moving the primary gear
selector to the forward or reverse position.
Lever steering must be engaged again by means of switch SW408.
Figure 4
Armrest (CDC)
SE 603 Steering lever
SW407 Activation, CDC
in armrest
SW 408 Activation, CDC
SW 409 Shifting,
forward –
reverse
SW 410 Kick-down
CU 601 Electronic unit

Lever steering (CDC), hydraulic system, description

Control valve
When steering lever SE603 is actuated an electric signal goes via electronic unit CU601 to
control unit 25 on the control valve (11 V or lower for steering to the left and 13 V or higher for
steering to the right).

Figure 1
Control valve with control unit
15 Control spool 24 Solenoid valve
21 Solenoid valve 25 Control unit,
CU601
22 Solenoid valve 27 Position sensor
23 Solenoid valve 28 Light-emitting
diode
Two of the solenoid valves (21-22 or 23-24) in the control unit are activated with the result that oil
is admitted on one side of control spool 15 which is moved and opens for a controlled flow of oil
to one of the steering cylinders. Position sensor 27 sends signals back to the control unit and
indicates the position of the spool. Oil is admitted until control spool 15 has been moved by an
amount corresponding to the lever movement and the desired steering speed has been achieved.
When the spool has moved to a position corresponding to the signal sent to the control unit, the
control unit cuts off the supply of current to solenoid valve 21 or 23, depending on the steering
direction.
The control valve’s control unit incorporates LED 28 which shines green during steering. If the
control valve spool fastens in the actuated position when the lever is returned to the neutral
position, the LED shines red. If such a fault should occur the machine will continue to turn even
though the lever is not actuated.
Pump pressure builds up for the steering valve and control valve. Pressure to valve spool  15 is
reduced by the pressure-reducing valve to approx. 2 MPa (290 psi).
When holding pressure has been built up the pumps angle down to "0 flow". When the steering
lever is actuated an electric signal goes via electronic unit CU601 to control unit MA601 on the
control valve. Oil is admitted to valve spool 15 which opens for a controlled flow of oil to the
steering cylinders.
The position sensor sends signals back to the control unit and indicates the position of the spool.
Fluid is admitted until the valve spool has been moved by an amount corresponding to the lever
movement.
The flow compensators of the pumps are activated by the LS pressure and adapt the flow and
pressure of the pumps to the current requirement.

Lever steering, adjusting steering speed

Op nbr 

1. The basic steering speed setting is 3.5–4.0 seconds between full left and full right lock (at
1500 rpm).
Steering speed is adjusted by turning the adjusting screws clockwise (increases speed)
or counter-clockwise (reduces speed).
The steering speed to the left and right should be as equal as possible, and the steering
lever must be fully deflected (maximum steering stroke) when the adjustment is
performed.
 Figure 1
Adjusting screws for steering speed
1. Steering, left
2. Steering, right

Lever steering, checking and adjusting control valve

Op nbr 
Lever for mechanical activation of control valve spool or suitable wrench
Checking
Connect the frame joint lock.
Apply the parking brake.

Figure 1

Fit the lever (wrench) for mechanical activation on the CDC valve, located under the cab on
the right side of the machine.
Start the engine and engage CDC lever steering with SW408.
Check to make sure that lever for mechanical activation does not move back and forth
(oscillate).
If the lever moves in any direction, the electronic and the hydraulic neutral positions are
not the same, and the lever will move back and forth.
Max. clearance: 2 mm (0.08 in)
 Figure 2

x Max. 2 mm
(0.08 in)
A Steering, left
B Steering, right
Adjusting
Any adjustment is performed on the adjusting screw (1). Turn the adjusting screw
anticlockwise or clockwise depending on whether the lever moves in direction A or B.
1/2 turn of the adjusting screw corresponds to a lever movement of 3 mm (0.12 in).

Figure 3
Adjusting lever movement in direction A