6
Description of components
DESCRIPTION OF BRAKE COMPONENTS
1-5
1.5 SERVICE-BREAK VALVE
Differential pressure between circuits 1 and 2
approx. 0.25 - 0.35 bar.
Purpose
The purpose of the service-brake valve is to
enable very precise bleeding and venting of air
to and from the service-brake circuits,
independently of each other.
Connection points
The circuit distribution is as follows:
Circuit 1: rear axle
Circuit 2: front axle
Connection 11
Circuit 1 supply
Connection 12
Circuit 2 supply
Connection 21
Circuit 1 braking
pressure
Connection 22
Circuit 2 braking
pressure
Operation
The service-brake valve consists of an
upper part (circuit 1) and a lower part (circuit 2);
both parts are provided with a connection
for the supply line (11 or 12) and the brake
line (21 or 22).
If the pedal is depressed, push rod (1), spring
retainer (2) and rubber regulating spring (3) will
exert force on regulating piston (4). The
regulating piston moves downwards, closes off
exhaust (5) and opens inlet (10). The reservoir
pressure at port 11 flows via chamber (A) and
port 21 to the brake chambers of circuit 1.
At the same time, compressed air flows via bore
(D) into chamber (B) above regulating piston (7),
which is forced downwards as a result. Exhaust
(9) is closed and inlet (8) opened. Via chamber
(C) and port 22, the reservoir pressure at port
12 flows to the brake chambers in circuit 2.
R600103
22
12
11
21
21
22
12
A
B
D
C
10
9
7
8
6
5
4
3
2
1
11
W604033
Fig.2
3
ǹ 0006