Troubleshooting guide

29
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The Control System: Lever Operated Control Valves
Relay Valve
Bendix
®
QR-1C
®
Quick
Release Valve
Bendix
®
QR-1C
®
Quick
Release Valve
Lever-Operated Control Valves
The Bendix
®
TW-2
™
and TH-3
™
valves are identical in
appearance (and similar to the Bendix
®
TW-1
™
, TW-3
™
,
and TW-4
™
valves) except they have two control valves
housed in a single body. These two valves differ by the
internal cammed control lever — which for the TW-2
control valve has two lever positions — while the TH-3
valve has three.
The Bendix TW-1, and TW-3-series control valves are
manually operated, non-modulating (on/off) control
valves used in a wide variety of control functions. The
Bendix TW-1 and TW-3 are dash-mounted, lever-
controlled valves.
The Bendix TW-4 is a manually operated, momentary
non-modulating control valve commonly used in
conjunction with air starter systems.
A momentary push-type control valve, the Bendix
®
TW-5
™
valve will deliver air pressure when the plunger
is pushed in and will exhaust delivered air when the
plunger load is released. A typical application is for
control of a differential lock-out.
The Bendix
®
TW-12
™
control valve is a manually-
operated, non-graduating, on/off valve. It is extensively
used in hydraulic braking systems to control devices
that are responsible for the application and release of
the parking brakes, but is also used in air brake system
applications.
The Bendix
®
TW-11
™
parking brake control valve is
a manually operated valve used in the hydraulic parking
system.
The Bendix
®
SL-4
™
and SL-5
™
stop lamp switches are
pressure-sensitive electro-pneumatic switches installed
in the service application system. They operate the
Bendix
®
TW-1
™
Valve
Bendix
®
TW-2
™
,
TH-3
™
Valve
Bendix
®
TW-3
™
Valve
Bendix
®
SL-5
™
Switch
Bendix
®
TW-11
™
Valve
Bendix
®
TW-12
™
Valve
vehicle stop lamps by completing an electrical circuit and
illuminating the stop lamps each time a brake application
is made.
See page 17 for the DS-2
™
double check valve and stop
light switch.
Dual Function Quick Release Valve
The Bendix
®
QR-1C
®
valve has a dual function. It works
as a quick release valve for rapid park brake actuation and
also provides anti-compounding, since its double check
valve prevents simultaneous service and emergency
spring brake applications.
Example of a
Quick Release
Valve used for
Spring Brakes
Bendix
®
TW-4
™
Valve