Bendix Commercial Vehicle Systems TC-2 TRAILER CONTROL BRAKE VALVE - Manual (Page 2)

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The exhaust seat, which is in the center of the piston,
contacts the exhaust valve and closes the exhaust passage
in the piston. The continued downward movement of the
piston moves the inlet valve off its seat. Reservoir air
pressure fl ows by the open inlet valve and out the delivery
port.
HOLDING
The air pressure that fl ows by the open inlet valve also
becomes effective on the bottom area of the piston. As
the force of the air pressure beneath the piston balances
the force of the depressed graduating spring above, the
piston lifts slightly and the inlet valve returns to its seat.
The exhaust valve remains seated so that the fl ow of air
through the valve is stopped and air pressure in the service
line is held.
RELEASING
When the handle (or operating lever) is moved in a
counterclockwise direction, the force above the piston is
decreased. The air pressure beneath will then lift the piston,
moving it away from the exhaust valve. With the exhaust
passage open, air pressure in the service line will exhaust
out the exhaust port of the valve.
PREVENTIVE MAINTENANCE
Important: Review the warranty policy before performing
any intrusive maintenance procedures. An extended
warranty may be voided if intrusive maintenance is
performed during this period.
Because no two vehicles operate under identical
conditions, maintenance and maintenance intervals will
vary. Experience is a valuable guide in determining the
best maintenance interval for any one particular operation.
Visually check for physical damage to the brake valve such
as broken air lines and broken or missing parts.
Every three (3) months, 25,000 miles, or 900 operating
hours, perform Operating and Leakage Tests.
SERVICE CHECKS
OPERATING TEST
Connect an accurate test gauge to a delivery port. When
the Bendix
® TC-2 ™ valve handle is moved to the fully
applied position, the gauge should register full reservoir
pressure. NOTE: Some valves may be preset to deliver
lower than reservoir pressure; however, the standard valves
generally used on tractors are set to deliver full reservoir
pressure. Intermediate positions should deliver proportional
intermediate pressures. Upon release, the gauge should
immediately register zero.
LEAKAGE TEST
Locate the exhaust port or exhaust line and apply a soap
solution. (It is common practice to connect a line from
the valve exhaust port to a location remote from the
immediate driver’s area.) With the valve in the released
position, exhaust leakage should not exceed a 1" bubble
in 5 seconds (100 sccm).
With the valve fully applied, leakage at the exhaust
should not exceed a 1" bubble in 3 seconds (175 sccm).
If the valve does not function as described, or leakage is
excessive, it is recommended that it be replaced with a
new or remanufactured unit, or repaired with genuine parts
available at an authorized Bendix outlet.
REMOVING AND INSTALLING
REMOVING
1. Block and hold the vehicle by means other than the air
brakes.
2. Drain the air brake system.
3. If the valve is a remote-operated type, disconnect the
operating mechanism.
4. Disconnect the air lines from the valve.
5. Remove the mounting clamp bolts, clamp, and then the
valve.
INSTALLING
1. Check and clean the air lines to the valve.
2. The operating mechanism for the remote-type valve
should be checked for functionally and for proper
adjustment.
3. Mount the valve with the clamp and mounting bolts.
4. Tighten the mounting bolts evenly to approximately 200
inch pounds torque (3/8-16 bolt torque 180-220 inch
pounds.)
5. If the valve is a remote-operated type, re-connect the
operating mechanism.
DISASSEMBLY
HANDLE OPERATED VALVE
1. Drive out the spiral pin and remove the handle, head,
and head seal o-ring.
2. Remove the handle o-ring.
3. For remote-operated type valve: Remove the set screw,
head and head seal o-ring.
4. Remove the adjusting ring lock washer.
5. Remove the cap screws that hold the body and cover
together; separate the cover from the body.
6. Remove the gasket and graduating spring.
7. Remove the cam and cam follower from the cover.
8. Unscrew and remove the adjusting ring.