Iveco EuroCargo (12 to 26 t). Manual — part 179
(continues)
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12-26 t
PNEUMATIC SYSTEM - BRAKES
61
Base - February 2003
DENOMINATION
INTERVENTIONS
Parking brake distributor
Parking brake distributor
(with control position)
Actuate the parking brake distributor till it snaps; the manometer
inserted on the control plug must mark the pressure discharge down
to 0 bar in 1 sec.
Simultaneously at the automatic coupling joint duct, the manometer
must show a pressure of 7.5 bar.
Quick discharge valve
Check functionality and seal.
Actuate the parking brake distributor, verify that the compressed air
is quickly discharged from the circuit.
Trailer braking triple-control
servodistributor
Fill-in the tank. Connect a manometer to the automatic coupling
head, and one to the moderate coupling head.
At a pressure of 1 bar, sent by Duplex distributor, in the moderate
coupling head a pressure from 0.8 to 1.5 bar must correspond. Carry
out a total braking (unmoving vehicle).
At the coupling head, the required braking pressure must be
available or a pressure decreased by 0.5 bar. Insert the parking brake;
at the moderate coupling head, the pressure must remain
unchanged or decreased by 0.5 bar.
Coupling heads
Check that there are no dirt or damages in coupling guides.
At the end of the coupling, actuate the brake pedal and check seal
and stability between coupling heads by inserting air at 7.5 bar.
Check that there is no air leakage from coupling gaskets.
Hydraulic or pneumatic pressure
control plugs
Make sure that protection plugs are inserted, check that they are
completely screwed.
Membrane cylinder
Check securing, integrity and seal.
The drain hole must be downwards oriented and must not be
clogged.
Combined cylinder
Check securing, integrity and seal.
The drain hole must be downwards oriented and must not be
clogged.
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DENOMINATION
INTERVENTIONS
Disc brake caliper
Brake disc
Braking gaskets
Check braking gaskets wear status, brake disc scorings and wear,
pistons efficiency, dust-guarding casing wear conditions.
Drum brakes
When ceasing the pressure on the pedal, the jaws must quickly and
smoothly go back on all wheels to their rest position.
Check clearance between jaws and drum.
Check braking gaskets thickness.
Pipings and fittings
Make sure that metal pipings are in a perfect condition, without
dents nor cracks; polyamide pipings must not show fissures, cuts or
nickings. Make further sure that they are far from body and chassis
cutting edges that could damage them. Check that all piping
anchoring brackets are well secured; their loosening in fact causes
vibrations with following danger of breakages. Verify that rubber and
cloth pipes have not come in contact with oil or mineral grease, that
are rubber solvents. Strongly press the brake pedal and check that
pipes do not show swellings, that signals leakages from internal pipe.
Check that there are no brake fluid leakages from various fittings,
otherwise it will be necessary to completely tighten them, with the
warning not to generate, during their closure, anomalous pipe
torsions. In all mentioned cases, it is necessary to replace the related
parts when there is even a minimum doubt about their efficiency.
Apart from their conditions, it is advisable to replace the hoses after
many kilometers or after a long period of vehicle use: this to avoid
a sudden breakage due to ageing and fatigue.
Pneumatic system seal with off
engine under the disconnection
pressure
This check is carried out on threaded fittings, inserting an air pressure
not less than 5 bar into the system, laying rather dense soapy water
on joints and fittings with a soft brush and observing that there are
no leakages. An air loss is tolerated corresponding to a
∅ 25 mm
soap bubble in 5 seconds, or anyway a max pressure drop within 10
min of 2% of disconnection pressure = 0.22 + 0.02 bar.
Pneumatic system seal in the
partial braking range with 3 bar
For 3 min the pressure must be kept stabilised in the pneumatic
system. The check must be carried out with disconnected parking
brake.
30411
It produces the necessary compressed air for braking system
and auxiliary services.
790510
COMPRESSOR
- Knorr
Figure 30
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12-26 t
PNEUMATIC SYSTEM - BRAKES
63
Base - February 2003
Diagnostics
INCONVENIENCE
POSSIBLE REASON
REMEDY
Oil leakages from flange, ex-
ternal side
Incorrect tightening torque.
Lock the screws according to the required values.
Not perfectly plane flange body sealing surfaces. Check sealing surfaces, replace faulty parts or take them
back on a plane.
Broken gasket.
Replace gasket.
Damaged shaft gasket.
Replace gasket.
Oil leakage from the head
Worn scraper ring (it is noted because all the
sealing seat is shining).
Replace the whole piston
Faulty scraper ring assembling.
It must be assembled with the writing TOP toward the
compressor head
Scraper ring and elastic bands all on the same
vertical line.
Assemble piston rings at 120º one form the other
Scored or ovalised cylinder.
Grind the cylinder and assemble a greater piston
Total lack of compression
Deteriorated compression or suction valve.
Replace the worn parts.
Elastic bands all on the same vertical line.
Assemble the bands at 120
° one to the other.
Holed piston or breakage of piston-related
members.
Replace the complete piston.
Damaged gaskets.
Replace the gaskets.
Scarce efficiency
Worn elastic bands.
Replace the piston (completed with elastic bands)
Air leakage between cylinder and head.
Replace the gasket and lock the screws at the required
tightening torque.
Excessive
clearance
between
piston
and
cylinder.
Grind the cylinder and assemble an increased piston.
Carbonised oil particles between suction and
compression valves.
Clean the valves.
Mechanical noise
Excessive clearance between connecting rod foot
and pin, between pin and piston hole, between
shaft and connecting rod head, between shaft and
bushings and between flanges and shaft.
Check affected couplings tolerance.
Excessive clearance between piston and cylinder.
Grind the cylinder and assemble an increased piston.
Excessive fouling between piston and cylinder
head caused by burnt oil.
Clean fouled parts and replace the valves.
Water blow-by
Scored and irregular head gasket or coupling
planes.
Replace the faulty parts.
Pneumatic connections
Electric connections
Drier
1 -
From compressor
3 -
Exhaust
24 -
To services
25 -
To pneumatic suspension
4-way valve
21 -
To rear axle air tank
22 -
To front axle air tank
23 -
To parking plus trailer air tank
24 -
To services
6.1 - Negative for thermostatic resistance
6.2 - Positive for thermostatic resistance
Its task is keeping cleanness and correct humidity of air in the
distribution system and keeping the necessary output
pressure for operating the connected systems.
This component integrates the functions of four-way pressure
regulator, pressure reducer for parking, services and trailer.
62628
Figure 31
Figure 32
E
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12-26 t
64
PNEUMATIC SYSTEM - BRAKES
Base - February 2003
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