BENDIX TC-7 TRAILER CONTROL BRAKE VALVE User manual

1
®
Bendix®TC-7™Trailer Control Brake Valve
SD-03-824
GRADUATING SPRING
VALVE
FIGURE 1
HANDLE
BRACKET
EXTERIOR VIEW
CAM FOLLOWER
LOCKWASHER
(SPECIAL)
RETAINING RING
ADJUSTING RING
ADJUSTING RING
ADAPTER
PARTIAL VIEW
(VALVE & HANDLE)
CAM
SCREW
DESCRIPTION
TheTC-7™trailercontrolbrakevalveisahandoperatedcontrol
valve that provides graduated control of service brake air
pressure. The most common vehicle application is the
independentcontrolofthetrailer’sservicebrakesonatractor
trailercombination.
Typically, the TC-7™valve is mounted either inside the
steering column or clamped to the exterior of the column.
ThethreebasiccomponentsoftheTC-7™valveareavailable
separately (valve, handle, bracket) to accommodate the
appropriatemounting configuration.
HANDLE
PISTON
O-RING
SPRING
INLET SEAT
O-RING
19
18
17
15
1
11
10
9
8
7
4
6
2
3
5
12
13
14
16
O-RING
FRICTION
WASHER
SEALING
RING
EXHAUST VALVE
BODY
INLET
VALVE
O-RING
SYSTEM
PARK TRACTOR
PARK
TRAILER
PARK
TRACTOR
PARK
BRAKE
CHAMBERS PP-1
SYSTEM
PARK
PP-8
OPTIONAL
T.M.C.
TRACTOR
PARK
LQ-4
RATIO VALVE TRAILER
CONTROL VALVE
E-7
DC-4 DS-2
DOUBLE CHECK
STOPLIGHT SWITCH
TP-3 TRACTOR PROTECTION
DC-4
DOUBLE
CHECK
VALVE
AIR
DRYER
COMPRESSOR
D-2 GOVERNOR
ST-3
SAFETY
VALVE SUPPLY
RESERVOIR LP-3 LOW
PRESSURE
INDICATOR GAUGE
REAR AXLE
SERVICE
RESERVOIR
CHECK
VALVE
FRONT AXLE
SERVICE
RESERVOIR
LP-3GAUGE
SR-1 SPRING
BRAKE VALVE
R-8 RELAY
VALVE
R-12 RELAY
VALVE
SPRING
BRAKES
SUPPLY LINE
SUPPLY LINE
ANTI-
COMPOUND
LINE
FIGURE2 -TYPICALPIPINGDIAGRAM
TRUCK/TRACTOR SYSTEM

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Because of its use as a trailer service brake control valve,
the TC-7™valve should NOT be used in lieu of the vehicle
parkingbrakes.The handleismarkedNOTFORPARKING.
In general the TC-7™valve should not be in use and left
unattended.
OPERATION
APPLYING
Whenthehandleoractuatingleverismoved in a clockwise
directionfromthereleasedposition, force is exerted on the
pressure graduating spring through the action of the cam
andcamfollower.Theforceofthespringonthepistoncauses
ittomove down.
The exhaust seat, which is in the center of the piston,
contactstheexhaust valveandclosestheexhaust passage
in the piston. The continued downward movement of the
piston moves the inlet valve-off its seat. Reservoir air
pressure flows by the open inlet valve and out the delivery
port.
HOLDING
The air pressure that flows by the open inlet valve also
becomeseffective on thebottom area ofthe piston. Asthe
force of the air pressure beneath the piston balances the
forceofthe depressed graduating spring above, the piston
liftsslightlyandtheinletvalvereturnstoitsseat.Theexhaust
valveremains seated so the flow of air through thevalve 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.Theair pressure beneathwillthenlift the piston,
moving it away from the exhaust valve. With the exhaust
passage open, air pressure in the service line will exhaust
outtheexhaust port of the valve.
PREVENTIVEMAINTENANCE
Important: Review the warranty policy before performing
anyintrusivemaintenanceprocedures.Anextendedwarranty
maybevoidedif intrusive maintenance is performed during
thisperiod.
Becauseno twovehiclesoperateunderidenticalconditions,
maintenanceandmaintenanceintervalswillvary.Experience
is a valuable guide in determining the best maintenance
intervalforanyone particular operation.
Visuallycheckforphysicaldamagetothebrakevalvesuch
as broken air lines and broken or missing parts.
Every3 months,25,000miles(40,000km.)or900 operating
hoursperformOperatingandLeakageTests.
SERVICE CHECKS
OPERATING TEST
Parkthe vehicle on a level surface and block the wheels.
Connect an accurate test gauge to the delivery port of the
TC-7™valve or connect the gauge to the service hose
couplingofthetractor.When the gauge is connected to the
service hose coupling, install a dummy hose coupling on
thesupply(emergency) hose coupling andplacethetractor
protectioncontrolin the trailer charging position. When the
TC-7™valve handle is moved to the fully applied position,
thegaugeshouldregisterfull 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
deliverproportional intermediate pressures. Upon
release,thegaugeshouldimmediatelyregisterzero.
LEAKAGETEST
Locate the exhaust port or exhaust line and apply a soap
solution. (It is common practice to connect a line from the
valveexhaustporttoalocation remote from the immediate
driver’sarea.)Withthevalveinthereleasedposition,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,itisrecommended that it be replacedwithanew
or remanufactured unit, or repaired with genuine parts
availableatBendixoutlets.
REMOVAL& INSTALLATION
The removal, disassembly, assembly and installation
proceduresarenumberkeyed to the sectional and exterior
viewsofthe TC-7™valve in Figure1.
REMOVAL
1. Block the wheels or hold the vehicle on a level surface
by means other than air brakes.
2. Drainallairpressurefromallreservoirs.
3. Identify the air lines and connections and remove from
theTC-7™valve.
4. Consult the vehicle manual for instructions on
disassembly of the steering column components.
NOTE: SomeTC-7™valveinstallationswillbeontheexterior
of the steering column, in which case Step 4 can
bedisregarded.

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5. RemovetheTC-7™valvehandle(16)byfirstremovingthe
flat head Phillips machine screw(14) from the center of
thehead/handleassembly.
6. DismounttheTC-7™valvefromthesteeringcolumn.
DISASSEMBLY
The following assembly and disassembly instructions are
written for the use of a Bendix Maintenance Kit 102145.
Ifthevalve is disassembledinavise,be sure thattheviseis
notovertightenedasthebodyandinternalpartswilldistort.
1. Removeanddiscardtheadjustingring lockwasher(3).
2. Removeandretain adjusting ring(6).
NOTE: Aspannerwrenchcanbeusedtorotatetheadjusting
ring, but if such a wrench is not available, the
adjusting ring can be returned with a small
screwdriver inserted in one of the inner notches of
thering.
3. Removeanddiscard retaining ring(2).
4. Removeadjustingringadapter(4),camfollower(5),sealing
ring(15)andfrictionwasher(17).Discardsealingring(15)
and o-rings (18 & 19). Retain all other parts.
NOTE: Note whether friction washer is installed with ribs
againstor away fromsealingring.Must be installed
same-wayduringassembly.
5. Removeandretain cam(7)andgraduatingspring(8).
6. Remove and retain piston(9). Remove and discard
o-ring(10)from piston(9).
7. Removeanddiscard piston return spring(11).
8. Using an 11/16" deep well socket wrench, remove and
discard inlet and exhaust valve assembly(12) and
o-ring(13).
ASSEMBLY
Priorto assembly, wash partsretainedduringdisassembly
inmineralspiritsanddrythoroughly.UsingBendixlubricant
291126 or a silicone lubricant equivalent to Dow Corning
55-M, lubricate the body bores, cam, cam follower and all
o-ringsando-ringgrooves.NOTE:Donotlubricatesealing
ring,frictionwasherorcamfollower serrations.
1. Installo-ring(13)oninletandexhaustvalveassembly(12)
and using an 11/16" deep well socket wrench, install
inletandexhaust valve assembly(12).Torqueto 15 inch
pounds.
2. Installpiston return spring(11).
3. Install o-ring(10) on piston(9) and install piston(9) in
body(1).
4. Installgraduatingspring(8)in body(1).
5. Installcam(7)in body(1)withflatsidetoward graduating
spring.Indexcam“ears”to corresponding slotsinbody.
6. Installrubbersealingring(15) on cam follower(5).
7. Installthefriction washer(17)oncam follower(5)insame
manner as noted in Step 4 of Disassembly.
8. Installcam follower(5)inbody.
NOTE: Stop“ear” on cam follower willnotpermitimproper
assembly of cam follower; however, make certain
that the positioning “ear” of the friction washer fits
in the wide slot in the body.
9. Installo-ring(18)in adjusting ring adapter(4) and install
o-ring(19)inadjusting ring(6).
10. Installadjustingring(6)inadapter(4)until adjustingring
isflush with the undersideof the adapter.
NOTE: There are two indexing lugs on the adapter that fit
into slots in the valve body when the adapter is
installed. Be sure to install the adjusting ring with
its wrench slots accessible (up) after the valve is
assembled.
11. Position the adapter(4) and adjusting ring(6) assembly
overthecamfollower(5),makingcertain theadapterlugs
fit into the body slots.
12. Push down on cam follower(5) and install snap ring(2).
Be certain the snap ring is completely seated in its
groove.
NOTE: Iflugson adapter(4) are not in theirbody slots, the
snap ring cannot be installed completely.
13. Beforeinstalling thelockwasher(3), adjustthe valveas
described.
ADJUSTMENT
Generally,theTC-7™brakevalveshoulddeliver fullreservoir
pressure; however, there are a few exceptions in special
applications.
1. Ifthedelivered pressure is below specifiedfinaldelivery
pressure, it can be adjusted by removing the head and
adjustingringlockwasher and rotatingtheadjustingring
clockwiseto raise the delivery pressure.
Careshouldbe taken not to raisethedelivery pressure
beyond the design limits; exhaust opening could be
restricted.
2. Ifthedelivery pressure is abovespecified final delivery
pressure, it can be lowered by rotating the adjusting
ringcounter-clockwise.
NOTE: Aspannerwrenchcanbeusedtorotatetheadjusting
ring, but if such a wrench is not available, the
adjustingringcanbeturnedwithasmallscrewdriver
inserted in one of the inner notches of the ring.
3. After adjustment is complete, install lockwasher(3) to
holdtheadjustment.

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INSTALLATION
1. Usingtheidentification made duringremoval,reconnect
theairlinestotheTC-7™valve. NOTE:Maximumtorque
for fittings is 10 ft. lbs.
2. Consultthevehiclemanualforinstructionsonremounting
the TC-7™valve in or on the steering column. Do not
overtorquethethree1/4-20mountingscrews.(30-60inch
pounds)(3.39-6.77kPa)
3. Remount the TC-7™valve handle(16) on the hex cam
follower(5) and secure flat head screw(14). Torque to
30-60inchpounds.(3.39-6.77kPa)
NOTE:Handlepositioncannotbeadjusted.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURYOR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
removed. Where circumstances require that the
enginebe in operation, EXTREMECAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
BW1568 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 3/2004 Printed in U.S.A.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Useonly the proper tools andobserve
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems,make certainto draintheair pressurefrom
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS™
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5. Following the vehicle manufacturer’s
recommendedprocedures, deactivate theelectrical
system in a manner that safely removes all
electrical power from the vehicle.
6. Never exceed manufacturer’s recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix®replacement parts,
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
9. Components with stripped threads or damaged
parts should be replaced rather than repaired. Do
not attempt repairs requiring machining or welding
unless specifically stated and approved by the
vehicle and component manufacturer.
10. Prior to returning the vehicle to service, make
certain all components and systems are restored
to their proper operating condition.