Troubleshooting guide

36
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Section 5: Converter Dolly Brakes
Typical components found in a converter dolly
brake system are shown in this section.
See section 12 for other system schematics.
Trailer/Converter Dolly Brakes
WS Sensor
“SR”
WS Sensor
“SL”
Bendix
®
DC-4
®
Double
Check
Valve
Bendix
®
TR-3
™
Parking
Brake
Control
Valve
Bendix
®
TABS-6
™
ABS
Module
MOD1
Bendix
®
PR-3
™
Pressure
Protection
Valve
Bendix
®
SV-4
™
Synchronizing
Valve
Single Check Valve
Bendix
®
R-12P
™
Relay Valve
Coupling -
Control
A - Brake Light Power
B - Ignition Power
C - NC
D - Indicator Lamp
E - Ground
5-Pin
Connector
Trailer Chassis
Harness
7-Pin
Connector
Control
Line
2S/1M -
Dolly Axle
Control
Dolly
ABS
Indicator
Lamp
Coupling -
Supply
Brake Light
Power
Ignition
Power
Supply
Line
Ground
Typical Converter Dolly Components
The Bendix
®
R-12P
™
pilot relay valve is a special purpose
relay valve designed specifi cally for use on trailers and
converter dollies. This 0 psi crack and differential relay
speeds up brake application signals to provide an equal,
or balanced, pressure signal to all trailer and dolly brakes
on double and triple trailer combinations. By maintaining
the same application signal across the entire train of
trailers, these pilot-operated relay valves aid in achieving
overall vehicle brake balance and stability.
The Bendix
®
SV-4
™
synchronizing (“synchro”) valve
is a remote-mounted, air-operated, on/off control valve.
It is used to control air from a remote supply, has a set
opening and closing pressure and can be used to delay or
sequence the action of other pneumatic devices. Use of
the SV-4 synchro valve in a dolly or towing trailer system
prevents automatic application of the towing (lead) trailer
or dolly emergency brakes in the event a breakaway
occurs with the towed (rear) trailer. The valve is used on
trailer converter dollies to minimize the possibility of false
charging.
Converter Dolly System Schematic (With Bendix
®
TABS- 6
™
ABS)