Open drain cocks and exhaust air pressure from
Every 7,200 Operating Hours or Every Two Years:
both upper and lower brake circuits.
D i s a s s e m b l e brake valve, clean and inspect all
Disconnect the air lines from E-4 brake valve.
parts. Install new parts where they are found to be
worn or damaged.
Remove mounting bolts, then valve.
SERVICE CHECKS
INSTALLING
OPERATING
Clean air lines to the brake valve.
Check the delivery pressure of both upper and
Mount the valve and tighten mounting bolts.
lower circuits using a test gauge known to be accu-
rate. Depress the pedal or treadle to several posi-
Connect air lines to brake valve.
tions between the fully released and fully applied
positions and check the delivered pressure on the
Test valve for serviceability as outlined in "Ser-
test gauges to see that it varies proportionately with
vice Checks" section.
the movement of the pedal or treadle. When the
treadle is fully applied the reading on the test gauge
should fall off to zero when the application is re-
DISASSEMBLY
leased. It should be noted that the upper circuit
Refer to Figure 4.
delivery pressure will be about 2.5 psi (.175 kg/cm2)
Complete E-4 Brake Valve
greater than the lower circuit delivery pressure with
u p p e r and lower circuit supply reservoirs at the
Remove three (3) mounting bolts.
same pressure. This is normal in this valve.
Remove and disassemble treadle or lever actu-
Build up air pressure in the system to approxi-
ating mechanism including roller, roller pin, ful-
mately 100 psi (7 kg/cm2). Drain the reservoir sup-
crum, pin, boot and plunger.
plying the upper circuit to the brake valve. Make
several full brake applications, and note pedal or
t r e a d l e force required to make application is ap-
Basic E-4 Brake Valve
proximately the same as with both circuits oper-
a t i n g . An increase in stopping distance, longer
D e p r e s s piston assembly (40) and hold down
treadle or pedal travel, or the low pressure warning
while removing piston retainer (1).
system indicates a malfunction in one or the other
circuits.
Remove piston assembly (40) and return spring
(8) from body (9).
LEAKAGE CHECK
Remove O-ring (7) from piston (6).
Make and hold a high pressure application. Coat
the exhaust port and top of the valve with soap
Remove cap screw (2) from top of piston assem-
suds. No leakage permitted.
bly (40).
If the brake valve does not function as described
Remove washer (3), rubber spring seat (4), and
above or leakage is excessive, it is recommended
rubber spring (5).
that it be returned to the nearest Bendix-Westing-
house authorized distributor for a factory recondi-
Using tru-arc pliers, remove retaining ring (39)
tioned valve under the exchange plan. If this is not
in exhaust port.
possible, the valve can be repaired with genuine
Bendix-Westinghouse parts in which the following
Remove exhaust check (38).
should prove helpful.
Remove lower inlet and exhaust valve assembly
REMOVING AND INSTALLING
(42).
REMOVING
Lower inlet and Exhaust Valve Assembly
Block or hold vehicle by means other than air
Remove lower valve guide O-ring (34).
brakes.
[11]
