SD-03-813

Bendix® TC-2™ Trailer Control Brake Valve

TC-2™ BRAKE
VALVE

CONTROL VALVE

TRACTOR
BRAKE PROTECTION EMERGENCY HOSE
VALVE VALVE
RESERVOIR

COMBINATION STOP LIGHT SWITCH

AND DOUBLE CHECK VALVE SERVICE HOSE

FIGURE 1 TC-2™ TRAILER CONTROL BRAKE VALVE TYPICAL PIPING DIAGRAM

DESCRIPTION
The TC-2™ brake valve is a hand operated control valve
which features a graduated control of air pressure. The
most common application is the control of trailer brakes
independent of tractor brakes; however, the valve may be
remotely operated type valve is connected to the operating
handle by a linkage rod.

The TC-2™ brake valve is not intended for use as a parking

control valve and should not be used for that purpose.

OPERATION
FIGURE 2 EXTERIOR VIEW
APPLYING
When the handle or actuating lever is moved in a clockwise
direction from the released position, force is exerted on the HOLDING
pressure graduating spring through the action of the cam The air pressure that flows by the open inlet valve also
and cam follower. The force of the spring on the piston becomes effective on the bottom area of the piston. As
causes it to move down. the force of the air pressure beneath the piston balances
the force of the depressed graduating spring above, the
The exhaust seat, which is in the center of the piston,
piston lifts slightly and the inlet valve returns to its seat. The
contacts the exhaust valve and closes the exhaust passage
exhaust valve remains seated so the flow of air through
in the piston. The continued downward movement of the
the valve is stopped and air pressure in the service line
piston moves the inlet valve off its seat. Reservoir air
is held.
pressure flows by the open inlet valve and out the delivery
port.
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RELEASING 3. If remote-operated type valve, disconnect the operating
mechanism.
When the handle or operating lever is moved in a
counterclockwise direction the force above the piston is 4. Disconnect air lines from valve.
decreased. The air pressure beneath will then lift the piston, 5. Remove mounting clamp bolts, clamp, and then valve.
moving it away from the exhaust valve. With the exhaust
passage open, air pressure in the service line will exhaust INSTALLING
out the exhaust port of the valve. 1. Check and clean air lines to valve.
2. Operating mechanism for remote type should be
PREVENTIVE MAINTENANCE checked functionally and for proper adjustment.
Important: Review the warranty policy before performing 3. Mount valve with clamp and mounting bolts.
any intrusive maintenance procedures. An extended
4. Tighten mounting bolts evenly to approximately 200
warranty may be voided if intrusive maintenance is
inch pounds torque (3/8-16 bolt torque 180-220 inch
performed during this period.
pounds.)
Because no two vehicles operate under identical 5. If remote type valve, connect operating mechanism.
conditions, maintenance and maintenance intervals will
vary. Experience is a valuable guide in determining the best DISASSEMBLY
maintenance interval for any one particular operation.
Visually check for physical damage to the brake valve such
HANDLE OPERATED VALVE
as broken air lines and broken or missing parts. 1. Drive out the spirol pin and remove the handle, head,
and head seal o-ring.
Every 3 months, 25,000 miles or 900 operating hours
2. Remove handle o-ring.
perform Operating and Leakage Tests.
3. Remote Operated Type Valve: Remove set screw, head
and head seal o-ring.
SERVICE CHECKS
4. Remove adjusting ring lock washer.
OPERATING TEST 5. Remove cap screws that hold body and cover together;
Connect an accurate test gauge to a delivery port. When separate cover from body.
the handle is moved to the fully applied position, the gauge 6. Remove gasket and graduating spring.
should register full reservoir pressure. NOTE: Some valves 7. Remove cam and cam follower from cover.
may be preset to deliver lower than reservoir pressure;
8. Unscrew and remove adjusting ring.
however, the standard valves generally used on tractors are
set to deliver full reservoir pressure. Intermediate positions 9. Remove piston and piston return spring from body.
should deliver proportional intermediate pressures. Upon 10. Remove piston o-ring.
release, the gauge should immediately register zero. 11. Remove inlet and exhaust insert screws and lock
washers, then insert and o-ring seal.
LEAKAGE TEST
12. The inlet and exhaust valve insert can be disassembled
Locate the exhaust port or exhaust line and apply a soap if desired or necessary.
solution. (It is common practice to connect a line from
13. Insert some object such as a cap screw in the supply
the valve exhaust port to a location remote from the
port to hold the inlet valve on its seat.
immediate driver’s area.) With the valve in the released
position, exhaust leakage should not exceed a 1" bubble 14. Depress the exhaust valve guide and spring; remove
in 5 seconds (100 sccm). the exhaust valve.
15. Remove stem with inlet valve from inlet seat and
With the valve fully applied, leakage at the exhaust
remove inlet valve from stem.
should not exceed a 1" bubble in 3 seconds (175 sccm).
If the valve does not function as described or leakage is CLEANING AND INSPECTION OF PARTS
excessive, it is recommended that it be replaced with a
1. Clean all metal parts in mineral spirits.
new or remanufactured unit, or repaired with genuine parts
available at Bendix outlets. 2. Wipe rubber parts clean.
3. Inspect valve seats for nicks or burrs.
REMOVING AND INSTALLING 4. Check all springs for distortion, cracks, and
corrosion.
REMOVING
5. All rubber parts should be inspected for wear or
1. Block and hold vehicle by means other than air deterioration.
brakes.
6. Replace all parts not considered serviceable during
2. Drain air brake system. their inspection with genuine Bendix replacement
parts.
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 Adjusting Ring
Lock Washer
Head
O-Ring
Adjusting Ring
Cam Follower
Cam Body
Spirol Pin Knob
Gasket O-Ring
Graduating Spring
Piston
O-Ring
Exhaust Valve
Piston
Return Spring Spring
Handle

Cover Stem TC-2™ Brake Head

Valve Insert
Inlet Valve
Seat
O-Ring Inlet Valve
Delivery Port Supply Port Exhaust Port

Head Seal
O-Ring

FIGURE 3 - SECTIONAL VIEW

ASSEMBLY 11. Connect body to cover; tighten cap screws evenly and
torque to 75-95 inch pounds.
Prior to assembly, lubricate the body and cover bores, cam
and cam follower, piston o-ring, and cover top with Dow 12. Install adjusting ring lock washer, head seal o-ring, and
Corning 55-M pneumatic grease (Bendix piece number head.
291126). 13. Install set screw in head of remote-operated type
1. Press inlet valve on stem. A little water in the boot valve valves. At this stage, before installing handle and
or some soap on the stem will make it easier to press spirol pin of handle-operated type valve, if facilities
on the inlet valve. are available the rebuilt valve should be tested and
adjusted. If facilities are not available, the valve can
2. PIace stem with inlet valve installed in inlet seat. Insert
be tested on the vehicle.
some object such as a cap screw to hold the inlet valve
up against its seat. TESTING REBUILT TC-2™ BRAKE VALVE
3. Position spring and exhaust valve guide. Perform “Operating and Leakage Tests” as outlined in
4. Depress guide and spring, then press exhaust valve “Service Checks” section.
on stem.
ADJUSTMENT
5. Place seal o-ring over insert seat and with cap screws
and lock washers install inlet and exhaust insert in body. Generally, the TC-2 ™ brake valve should deliver full
Recommended torque on insert cap screws is 60 to 80 reservoir pressure; however, there are a few exceptions
inch pounds. in special applications.
6. Install piston return spring. 1. If the delivered pressure is below specified final delivery
7. Install piston o-ring on piston and install piston in pressure, it can be adjusted by removing the head and
body. adjusting ring lock washer and rotating the adjusting
ring clockwise to raise the delivery pressure.
8. Install adjusting ring in cover and screw it down until it
is flush with top of cover. 2. If the delivery pressure is above specified final delivery
pressure, it can be lowered by rotating the adjusting
9. Place cam follower and cam in cover.
ring counterclockwise.
10. Position graduating spring and gasket in body.
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A spanner wrench can be used to rotate the adjusting ring, from all reservoirs before beginning ANY work
but if such a wrench is not available, the adjusting ring on the vehicle. If the vehicle is equipped with an
can be turned with a small screwdriver inserted in one of AD-IS® air dryer system or a dryer reservoir module,
the inner notches of the ring. Turning the adjusting ring be sure to drain the purge reservoir.
one notch will raise the delivered pressure approximately 5. Following the vehicle manufacturer’s recommended
5 psi. procedures, deactivate the electrical system in a
manner that safely removes all electrical power
WARNING! PLEASE READ AND FOLLOW from the vehicle.
THESE INSTRUCTIONS TO AVOID PERSONAL 6. Never exceed manufacturer’s recommended
pressures.
INJURY OR DEATH:
7. Never connect or disconnect a hose or line
When working on or around a vehicle, the following containing pressure; it may whip. Never remove
general precautions should be observed at all times. a component or plug unless you are certain all
1. Park the vehicle on a level surface, apply the system pressure has been depleted.
parking brakes, and always block the wheels. 8. Use only genuine Bendix® replacement parts,
Always wear safety glasses. components and kits. Replacement hardware,
2. Stop the engine and remove ignition key when tubing, hose, fittings, etc. must be of equivalent
working under or around the vehicle. When size, type and strength as original equipment and
working in the engine compartment, the engine be designed specifically for such applications and
should be shut off and the ignition key should be systems.
removed. Where circumstances require that the 9. Components with stripped threads or damaged
engine be in operation, EXTREME CAUTION should parts should be replaced rather than repaired. Do
be used to prevent personal injury resulting from not attempt repairs requiring machining or welding
contact with moving, rotating, leaking, heated or unless specifically stated and approved by the
electrically charged components. vehicle and component manufacturer.
3. Do not attempt to install, remove, disassemble 10. Prior to returning the vehicle to service, make
or assemble a component until you have read certain all components and systems are restored
and thoroughly understand the recommended to their proper operating condition.
procedures. Use only the proper tools and observe 11. For vehicles with Antilock Traction Control (ATC),
all precautions pertaining to use of those tools. the ATC function must be disabled (ATC indicator
4. If the work is being performed on the vehicle’s lamp should be ON) prior to performing any vehicle
air brake system, or any auxiliary pressurized air maintenance where one or more wheels on a drive
systems, make certain to drain the air pressure axle are lifted off the ground and moving.

BW1430 © 2007 Bendix Commercial Vehicle Systems LLC. All rights reserved. 6/2007 Printed in U.S.A.
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