Section 12: BRAKE AND AIR SYSTEM
PA1562
13
1. Replace the linkage, loosen threaded rod
lock nuts and screw or unscrew the
threaded adjustment rod in order to obtain a
45
o
brake pedal inclination (Fig. 14).
2. Tighten threaded rod lock nuts.
14.1.1 Maintenance
Maintenance and repair information on the E-10P
dual brake application valve is supplied in the
applicable booklet annexed to this section under
reference number SD-03-830.
FIGURE 14: BRAKE PEDAL ADJUSTMENT 12208
15. STOPLIGHT SWITCHES
Two electro-pneumatic stoplight switches are
mounted on the dual brake application valve (E-
12). The upper one is used for the primary air
circuit while the lower one is used for the
secondary air circuit. Both switches are
connected in parallel and have the same
purpose, i.e. completing the electrical circuit and
lighting the stoplights when a brake application
is made. The upper switch (AC Delco) is
designed to close its contact between 2 psi and
4 psi (14 kPa to 28 kPa) (Fig. 15), while the
lower one (Bendix, SL-5) closes its contact at 4
psi (28 kPa) (Fig. 16). The switches are not
serviceable items; if found defective, the
complete unit must be replaced.
FIGURE 15: DELCO SWITCH 12139
FIGURE 16: BENDIX SWITCH 12140
16. PARKING BRAKE ALARM SWITCH
Refer to the appropriate annexed booklet
(Bendix, SL-5 Stop Light Switch; reference no.
SD-06-2501).
The parking brake alarm uses the same switch
as the stoplights. It is mounted on the spring
brake valve and operates in conjunction with a
NC relay to sound a warning alarm by
completing the electrical circuit when the ignition
key is turned OFF with parking brake released.
17. BRAKE RELAY VALVE (R-12 & R-14)
The primary air system includes three brake
relay valves being supplied by the dual brake
valve, and which function is to speed up the
application and release of the service brakes.
One Wabco R-14 valve located in the rear
underframe supplies the drive axle service brake
air line, while the other two R-12 valves supply
independently both the tag axle right and left
service brake air line and act as interlock valves.
These valves are accessible from under the
vehicle at the level of the tag axle. Maintenance
and repair information on these valves is
supplied in the applicable booklet annexed to
this section under reference number
SD-03-1064.
FIGURE 17: R-12 12074
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