Bendix Commercial Vehicle Systems BP-1 BRAKE PROPORTIONING VALVES - Manual (Page 3)

3
FIGURE 4 BP-1 ™ REAR BRAKE PROPORTIONING VALVE
CUTAWAY VIEW
delivers 50% of the service application to the actuators.
Service pressures above 40 psi begin to displace the upper
piston and the differential between the supply and delivery
diminishes until at 60 psi the spring force under the upper
piston is totally overcome and the valve delivers a one-to-one
ratio. See Figure 3, limiting mode.
With the trailer supply valve released, air pressure to the
trailer is exhausted to atmosphere. At the same time the air
pressure to the control port of the TR-3
™ inversion valve is
also exhausted. This sequence causes full reservoir
pressure to be delivered to the control port of the BP-1
™
valves. The air entering the control port of the BP-1 ™ front
valve acts upon the lower piston, closing the exhaust and
holding the inlet open. In this position when a service brake
application is made, 100% of the pressure received at the
supply port of the BP-1
™ front valve is delivered to the
actuators on the front axle. See Figure 3, full delivery mode.
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO AVOID
PERSONAL INJURY OR 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
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
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 certain to drain the air pressure from
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
recommended procedures, deactivate the electrical
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.
4
3/8 P.T.
SUPPLY
3/8 P.T.
DELIVERY
BODY
6
5
1
2
3
7
8
UPPER
PISTON
1/8 P.T.
CONTROL
EXHAUST
LOWER
PISTON
INNER
PISTON
COVER
2.78
4.34
Key Description Qty.
1
O-Ring 2 5 Inlet/Exhaust Valve 1
2 O-Ring 1 6 Spring 1
3 O-Ring 1 7 Sealing Ring 1
4 O-Ring 1 8 Spring 1
FIGURE 5 BP-1 ™ FRONT BRAKE PROPORTIONING VALVE
CUTAWAY VIEW
4
3/8 P.T.
SUPPLY
3/8 P.T.
DELIVERY
BODY
6
5 1
2
3
7
UPPER
PISTON
1/8 P.T.
CONTROL
EXHAUST
LOWER
PISTON
COVER
2.78
4.34
Key Description Qty. 4 Spring 1
1 O-Ring 1 5 Inlet/Exhaust Valve 1
2 O-Ring 1 6 Spring 1
3 O-Ring 1 7 Sealing Ring 1