6
Inspection and adjustment
BRAKE COMPONENTS
1-23
1.13 INSPECTION AND ADJUSTMENT, BRAKING-PRESSURE ADVANCE IN
(SEMI-)TRAILER REACTION VALVE
WABCO design
Inspection braking-pressure advance in
(semi-)trailer reaction valve
Note:
The pressure ratio between prime mover and
(semi-)trailer is 10 : 8 (10 bar system pressure
for prime mover and 8 bar system pressure for
(semi-)trailer).
This means that if no braking-pressure advance
is applied, at an input pressure of 3 bar at port
(41), the output pressure at port (2) is equal to
(3 x 8) : 10 = 2.4 bar If a braking-pressure
advance of 0.6 bar is now applied, the output
pressure at port (2) should be: 2.4 + 0.6 =
3.0 bar.
1.
Connect a pressure gauge (1) to the test
connection for the load-sensing valve and a
pressure gauge (2) to the service coupling
head.
2.
Depress the brake pedal until the input
pressure (measured at pressure gauge 1) is
3 bar.
The reading at pressure gauge (2) should
now be 3.0 bar. This equals 0.6 bar
braking-pressure advance.
3.
If the braking performance of the
(semi-)trailer (provided it is in good
condition) is poorer than that of the tractor,
the braking-pressure advance may be
increased by several tenths of a bar.
Braking-pressure advance adjustment in
(semi-)trailer reaction valve
Note:
The pressure at which the readings are taken
must always be built up. If the specified
pressure is exceeded, bleed off some air, and
once again let the air pressure build up.
1.
Slacken the 4 screws of the exhaust (3) and
remove the silencer.
2.
Using a philips-head screw driver, turn
adjusting screw (9) counter-clockwise.
R600123
3
9
5b
5a
2
4
5
6
7
42
22
12
43
11
41
4
ǹ 0006