Iveco EuroCargo (12 to 26 t). Manual

Recharge phase:
The compressed air coming from the compressor through
the supply fitting ”11” is arranged on the safety valve ”a”
(calibrated at 13+4 bar) and through the suitable channel it
reaches the drier filter.

Compressed air gives off, as it passes through the filter, its
own moisture and feeds the timer ”b” chamber through the
calibrated hole. At the same time, it opens the unidirectional
maintain valve ”c”, thus feeding the outlet 24 pressure intake,
pressure regulator ”d”, pneumatic suspension circuit feed
outlet 25 and, through outlet 21, the four-way protection
valve.

This

valve

will

convey

the

air

below

the

controlled-pressure valves of brake system outlets 21 and 22.

When

pressure of

≤ 7,5 bar is reached, the

controlled-pressure valves will open, thus making it possible
to feed the systems connected.

Simultaneously, through the two unidirectional valves ”e”, air
can reach the controlled-pressure valve of the secondary
sections.

The further pressure increase and reaching a pressure > 8 bar
allow opening the controlled-pressure valves in the
secondary sections and consequently supplying the outlets
23 and 24

(continues)

62629

Figure 33

URO

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12-26 t

PNEUMATIC SYSTEM - BRAKES

Base - February 2003

When reaching the regulator calibration pressure of 10.3

+0.2

bar, there occurs the opening thereof and the consequent

opening of discharge valve ”h” that generates a pressure drop
inside the drier and the unidirectional keeping valve ”c”
closure and the activation of the drier filter regeneration step.
The slow pressure drop of the timer supply chamber allows
the pressure return from systems for a time of about 20
seconds. The compressed air returning from systems, when
passing through the filter, will guarantee its regeneration and
will discharge itself in the atmosphere through vent 3.

Failure phase of duct 21
In case there is a failure to main four-way protection valve
circuit, the component will behave as follows:

The pressure drop that affects outlet 21 creates a general
pressure drop in the whole component till the closure
pressure is reached (6.5 bar) for the controlled-pressure valve
in the faulty section.
This pressure decrease also goes to the regulator ”d” that by
moving itself goes back to its recharge condition.
The pressure drop in duct 21 creates the displacement and
discharge opening of the safety valve ”f” for the parking duct,
that discharges the protection valve duct 23. With moving
vehicle, the parking cylinders supply will be guaranteed either
by the manual self-limited distributor (single vehicles) or by
closing the unidirectional valve (vehicles adapted for towing)
avoiding the vehicle self-braking.

With any protection valve failure, the system supply
is ensured at pressure levels that guarantee brake
functionality but filter regeneration will not be
ensured any more since this function is only
activated when reaching the regulator triggering
pressure.

Under this failure condition, the possible connected trailer will
instead be automatically braked.

The system recharge, ensured by the regulator intervention,
will take back the pressure at the opening levels of the
controlled-pressure valve of the faulty section (about 7.5 bar),
guaranteeing this pressure in all other component outlets.

The possible failure of all other sections will guarantee that the
faulty valve opening pressure is kept for the healthy sections.

Diagnostics

INCONVENIENCE

POSSIBLE REASON

REMEDY

Excessive amount of
condensate in the cir-
cuit

The calibration pres-
sure is not reached in
the tank

Exhaust air leakage

Air leakage next to
plugs

Air leakage in case of
section failure

Clogged filtering cartridge.

Air leakage from safety valve.

Worn sealing gaskets.

Insufficient piston seal.

Valve leakages in the four sections.

Faulty non-return valve operation.

Replace the cartridge

Revise the device replacing the worn parts

Revise the device replacing the worn parts.

Revise the device replacing the worn parts, if necessary,
or replace the device.

URO

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12-26 t

PNEUMATIC SYSTEM - BRAKES

Base - February 2003

It is an on/off solenoid valve of the N.C. type placed on the
chassis.
This solenoid valve, driven by the unit, suitably supplies the
engine brake control operating cylinder. A luminous signaller,
placed on the dashboard, signals the engine brake insertion.

62382

793336

ENGINE BRAKE SOLENOID VAL-
VE

ENGINE BRAKE SWITCH

It is a N.O. switch assembled on cabin floor. It provides a
negative signal to the electronic unit for inserting the engine
brake.

62372

Figure 34

Figure 35

543730

ENGINE BRAKE CONTROL
OPERATING CYLINDER

Figure 36

Figure 37

MANUAL DISCHARGE VALVE

The operating cylinder actuates the throttle valve clogging
the engine exhaust gases duct.

72658

71957

This valve is assembled in tanks and its function is manually
removing the possible condensate accumulated in the
system tanks.

URO

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12-26 t

PNEUMATIC SYSTEM - BRAKES

Base - February 2003

The device is divided into two independent sections whose
adjustment members are controlled in parallel by a push rod
that operates on an equalizer.

It takes air from tanks and delivers it to braking elements.

It is self-limited, that is, it limits air delivery at a maximum
established pressure and therefore there occurs a higher
energy availability and a constant maximum braking pressure
independently from pressure oscillations in tanks.
Pneumatic connections
11 -

From rear axle air tank

12 -

From front axle air tank

21 -

To rear axle

22 -

To front axle

3 -

Discharge

793110

DUPLEX DISTRIBUTOR

SAFETY VALVE (Optional)

It ensures the system limiting at a safety pressure in case of
lack of pressure regulator operation.

71959

Figure 38

Figure 39

Figure 40

Electric connections
1 -

Free

2 -

Positive for STOP lights/Body Controller

3 -

Input positive

4 -

EDC positive

71951

The diagram shows the characteristic distributor curve and
the self-limitation value at 7.6

± 0.3 bar.

62579

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12-26 t

PNEUMATIC SYSTEM - BRAKES

Base - February 2003

Content .. 178 179 180 181 ..

Iveco EuroCargo (12 to 26 t). Manual - part 180