Iveco EuroCargo (12 to 26 t). Manual — part 161
PISTON RIGHTWARDS DISPLACEMENT (open steering limiting valves, very reduced oil pressure)
HYDRAULIC STEERING LIMITING (both steering limiting valves are closed)
T. Right steering limiting valve — U. Left steering limiting valve — V. Right cylinder chamber — W. Left cylinder chamber —
X. Left adjustment screw — B. Piston — Y. Right adjustment screw.
Hydraulic steering limiting
Two valves (T and U) are axially arranged in the piston (B,
Figure 6) for steering limiting. They are equipped with small
spring-loaded pistons, whose stems project from right and left
front piston surfaces.
If the piston is rightwards or leftwards displaced along limit
stop direction, the stems can reach the adjustment screws (X
and Y) in the case and cover, and move. Both limiting valves
remain closed till one of the stems touches the adjustment
screw. If for example the piston is rightward displaced
(Figure 7), the right steering limiting valve (T) is opened by
screw (X) before the piston reaches the limit stop.
In such a way, the pressurised oil being present in the left
operating cylinder chamber can penetrate into its right
chamber, flowing around the displaced valve piston (U) and
through the open right valve (T), and then reach the return
circuit. If the piston is leftwards displaced, the valve (U) is
opened after the pre-established stroke and the pressurised
oil in the right cylinder chamber can flow into the return
cylinder, thereby reducing the pressure into the circuit
chamber.
When the steering limiting valve is open, hydraulic
servoassistance is strongly reduced and the steering wheel can
be rotated only with a higher effort till wheel or drive stop.
27202
27203
Figure 6
Figure 7
E
URO
C
ARGO
T
ECTOR
12-26 t
STEERING
13
Base - February 2003
33687
Remove split pin (1) and unscrew nut (2).
33688
Through extractor 99347068 (2) detach tie-rod (1) from
lever (3).
Figure 8
Figure 9
Figure 10
Figure 11
Disconnection
Place a vessel under the hydraulic power steering and remove
cover from tank.
Unscrew fittings (1 and 2) and detach oil delivery and return
pipings from hydraulic power steering.
33686
33689
Unscrew screw (1) and disconnect connection joint. Unscrew
screws (2) securing hydraulic power steering to support.
E
URO
C
ARGO
T
ECTOR
12-26 t
14
STEERING
Base - February 2003
HYDRAULIC POWER STEERING
DISCONNECTION AND
RECONNECTION (ZF 8095-8098)
Figure 12
33691
33693
33692
- Check angular lever excursion that must be equal to 47
°
in both directions;
- lock lever securing nut (2) through a dynamometric
wrench (1) at the required torque.
- through a suitable punch, press nut collar (1).
Lubricate with oil all screws securing hydraulic power
steering to support.
33690
Reconnection
Suitably reverse the operations carried out for the
disconnection; tighten the screws at the required
tightening torques.
- secure the hydraulic power steering into a vice;
- assemble steering lever (3) making notches (1) align
etched on drive shaft (2) and on lever (3);
Having to replace the hydraulic power steering with
a new one, before its assembling on the support, carry
out the following operations.
Figure 13
Figure 14
Figure 15
!
!
E
URO
C
ARGO
T
ECTOR
12-26 t
STEERING
15
Base - February 2003
Figure 16
1. Pump — 2. Tank — 3. Delivery piping — 4. Suction piping —
5. Reflow piping — 6. Manometers
X = Hydraulic steering limiting adjustment screw for
rotating steering control arm along “A” direction.
Y = Hydraulic steering limiting adjustment screw for
rotating steering control arm along “B” direction.
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19587
f. Dimension (see table) for the spacer to be interposed
between stops — 7. Stop
With the pair of manometers 99374393 already connected
on hydraulic power steering delivery piping fitting, abut the
front wheels onto rotating plates.
Place a spacer (f, Figure 16) of the shown thickness, see table
enclosed below, between wheel stop parts (7).
f SPACER THICKNESS, WITHOUT CODE
Front mechanical suspension
Left wheel
Right wheel
No-loaded vehicle
3 mm
6 mm
Full-loaded vehicle
3 mm
3 mm
Front pneumatic suspension
No-loaded or
3 mm
3 mm
full-loaded vehicle
Always with front wheels on rotating plates, start the engine
up and keep it at a speed
≤ 1550 revs/min.
Steer till the wheel stops against the spacer; then, go on
steering the steering wheel for a few seconds exceeding in
such a way the steering valve reaction force till the fixed stop
is reached.
In such position the manometer will have to point out an oil
pressure equal to 35
÷ 50 bar.
In order to correct different values, the lock nut is unscrewed
and the screw of the corresponding valve (X or Y, Figure 17)
is screwed or unscrewed.
During such phase, it is necessary to let the steering wheel free
in order to avoid undesired pressure increases.
Then close the lock nut at a torque of 30
± 5 Nm (3 ± 0.5 kgm);
to adjust the second wheel stop, proceed in a similar way.
When the hydraulic power steering moves to A (Figure 17),
adjust valve (X), when it moves to B (Figure 17), adjust valve
(Y).
When the shown pressure is greater than 50 bar, it is
necessary to (clockwise) screw the corresponding steering
limiting valve.
When the shown pressure is lower than 35 bar, it is necessary
to (counterclockwise) unscrew the corresponding steering
limiting valve. At the end of the adjustment, check again the
pressure drops along the two steering directions.
Figure 17
E
URO
C
ARGO
T
ECTOR
12-26 t
16
STEERING
Base - February 2003
HYDRAULIC STEERING LIMITER
ADJUSTMENT
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