Iveco Daily Euro 4. Manual

The oil coming from the pump through the joint (3) goes into the distributing valve and it is sent to the hydraulic cylinder chamber
(2) causing the movement of the piston. This movement pushes the oil contained into the chamber (1), through the joint (4), into
the tank passing again in the distributing valve.
The movement of the piston in the direction of the arrow shows a left steering.
The drive shaft (A), rotating clockwise with respect to the distributing valve (B), drives the oil under pressure coming from the pump
through the ports (C), to the left chamber along the ports (D) and joins the discharge and the right chamber circuit by means of
the ports (E).

HYDRAULIC POWER STEERING OPERATION DIAGRAM: NEUTRAL POSITION

HYDRAULIC POWER STEERING OPERATION DIAGRAM: LEFT STEERING

24107

19594

Figure 7

Figure 8

POWER STEERING TYPE ZF
Operation

With the steering wheel positioned to straight running, the bush (2) is arranged so that the passage of both feeding and discharge
oil of the operating cylinder is closed.
The oil pressures in the right and left chamber of the operating cylinder are balanced.
The oil under pressure coming from the power steering pump (4) through the piping (5) feeds the distributor (1) central grove, flows
in the bush (2) splines, goes out from it and, through the piping (6) returns in the tank (3).
The neutral position of the hydraulic power steering is obtained and, therefore, the vehicle straight ride.

HIGH PRESSURE

LOW PRESSURE

HIGH PRESSURE

LOW PRESSURE

STEERING GEAR

AILY

URO

The oil under pressure coming from the power steering (4) pump, through the piping (5), feeds the distributor (1) passing in the
central groove.
The rotation of the steering wheel causes a semi-rotation of the bush (2), this one is positioned so that the oil flows in its three splines
and is sent to: the distributor upper groove, in case of right steering (figure 10), or in the distributor lower groove, in case of left steering
(figure 11). The latter sends it to the relevant feeding piping (depending on the steering direction) of the operating cylinder chambers.
Meanwhile, the oil contained in the chamber opposite to the fed one returns in the distributor. From the latter one, it flows in the
discharge grooves of the bush (2) then, through the piping (6), returns in the tank (3).
In this way the hydraulic interlocking is obtained.

19595

19596

Figure 9

Figure 10

HYDRAULIC POWER STEERING OPERATION DIAGRAM: LEFT STEERING

HYDRAULIC POWER STEERING OPERATION DIAGRAM: RIGHT STEERING

HIGH PRESSURE

LOW PRESSURE

HIGH PRESSURE

LOW PRESSURE

STEERING GEAR

AILY

URO

Join a pressure gauge (2) on the oil delivery piping on the
power steering pump (1). Rotate the steering wheel up to the
limit stop, speed up the engine and read on the pressure gauge
the maximum pressure value, which mast be of 80 bar.

Check the oil level in the tank, if necessary top up.
Lift the front part of the vehicle, start the engine and make it
idle for a certain period.
Check that there is no oil leakage from the hydraulic circuit and
check the tank level.
Slowly rotate the steering wheel in the two steering directions
so that the air contained in the hydraulic system goes out.
Check again the oil level in the tank and, in case top up.

Lift the front of the vehicle and put the wheels in the straight
ride position.

Start the engine and fully speed up; if the steering gear put itself
in steering position, the hydraulic steering centre is wrong and
the hydraulic power steering must be changed.

501430

Bleeding the air from the hydraulic
system

The only possible interventions on the power
steering and mechanical steering systems are:
replacement of ball joints, replacement of protective
rubber boots, linkages and rubber bushings. Follow
the instructions provided in the specific paragraphs.
Replace the power steering system if problems
referred to this system only are found.

19598

32875

Figure 11

Figure 12

CHECKS AND OPERATIONS ON THE
VEHICLE
Checking maximum pressure

520636

SWIVEL HEADS

501438

PROTECTION CASINGS

Check that the protection casings of the knuckle heads are in
perfect condition and that their pivots do not present play,
otherwise replace them as described below.
Loosen the nut (3) securing the knuckle head (2) to the tie rod
(4).
Remove the nut fixing the knuckle head to the steering gear
lever and using the extractor (1) 99347074 remove the
knuckle head.
Unscrew knuckle head from the tie rod of the steering box
noting down the number of turns needed to disassemble.
Remove the fixing brackets (5) and extract the protection
casing (6).
In order to re-fit the assembly, perform the above operation
in reversed order, sticking to the following instructions:
- carefully clean the steering gear tie rod knuckle;

- lubricate the protective boot seats on the power steering

box to facilitate assembly;

- screw up the knuckle head with the same number of turns

used to disassemble it;

- fit a new o-ring on the power steering box;

- tighten the nuts of the prescribed torque;

- Adjust toe-in as shown in the respective section.

Checking hydraulic steering centre (for ”ZF”
power steering only)

501410

STEERING GEAR CONTROL

Vehicles equipped with an Air-Bag

Before doing any work on steering gear control
components:

- steering wheel;

- steering control lever system;

- steering gear shaft
Strictly observe the safety standards described in the following
paragraphs for Air-Bag system components.

NOTE

STEERING GEAR

AILY

URO

System components are designed to operate just on vehicles
of the specified make and type. Air-Bags must therefore not be
adapted, reused or installed on other vehicles.
Mount and use them only on the vehicles for which they have
been designed and produced.

The following Standards shall be strictly observed
when performing any type of repair or maintenance
operations on vehicles equipped with Air-Bag safety
system.

Air-Bag modules shall be handled with the utmost care.
Use, transport and storage of these components are
governed by the handling procedures described in the
following paragraphs.

Component removal and refitting shall be performed
EXCLUSIVELY by skilled and authorised personnel.
Failure to comply with the following procedure can
result in unintentional activation of the system, severe
injury or repairs not required. IT IS ABSOLUTELY
FORBIDDEN TO DISASSEMBLE Air-Bag MODULE
COMPONENTS.

Any reuse, adaptation or installation on a different
type of vehicle can result in sever injury or death for
passengers in case of collision.

Repairs and inspections required after an
accident

Any safety system component damaged after an
accident must be replaced.
Do not attempt to repair the control unit, the coil
cable or the Air-Bag modules.

Accidents with or without Air-Bag module
activation

Certain system components must be inspected after any crash,
whether the Air-Bag deployed or not. These components are
the following:

- steering column;

- steering column support;

- electronic control unit anchoring area and modules;

- coil cable;

- dashboard (in the area of the passenger Air-Bag).

If any faulty condition is found, replace the faulty component.

Accidents with Air-Bag module activation

In case of front impact with total system activation, the
following components must be replaced:

- Air-Bag modules;

- pretensioners;

- electronic control unit;

- coil cable.

STEERING GEAR

AILY

URO

SAFETY STANDARDS TO BE OBSERVED
DURING REPAIR OR MAINTENANCE OPE-
RATIONS ON VEHICLES EQUIPPED WITH
AIR-BAG SYSTEM PROVIDED BY SUPPLIER

Preliminary Standards

Before starting any bodywork repair operation, welding or
whatever work requiring to remove the Air-Bags or the control
unit, proceed as follows:
- set ignition key to ”STOP” and take it out;

- always disconnect the battery, i.e.: disconnect the two

terminals from the relevant pole and insulate them
properly by tape;

- wait for at least 10 minutes before proceeding;

- disconnect control unit connector.

Store modules with the cover set upwards, inside a metallic
key-locked cabinet that must be used just with this purpose and
that must not contain other type of materials, especially if
flammables.

Adopted connectors wired to Air-Bag modules are provided
with short-circuit clip. It is impossible to activate units
accidentally until Air-Bag modules are connected to a power
source with suitable properties.

A system component not activated in case of collision is to be
considered still ”live” (active).

Live components that shall be removed from vehicles (due to
defects, warranty expiry or other reasons) shall be returned to
the suitable Centre using the following procedure.

Content .. 194 195 196 197 ..

Iveco Daily Euro 4. Manual - part 196