BENDIX TYPE E6 & E7
Two types of Bendix brake valves are used; they are
treadle type (E6) and suspended type (E7).
The brake valve is the control unit of the air brake
system. It provides the operator of the vehicle a means
of applying or releasing the vehicle brakes. The brake
valve can either be treadle operated or fitted with a
suspended pedal lever.
Both the treadle and suspended brake valves are
equipped with two separate supply and delivery circuits
for service and emergency braking, providing the driver
with a graduated control for applying and releasing the
The primary circuit is that portion of the valve between
the spring seat which contacts the plunger and the relay
piston. The secondary circuit is that portion between the
relay piston and exhaust cavity.
Fig. 1 Treadle Type Brake Valve
The primary circuit is similar in operation to a standard
single circuit air brake valve and under normal operating
conditions the secondary circuit portion is similar in
operation to the relay valve.
Both the primary and secondary circuits of the brake
valve use a common exhaust check valve,
The text and illustrations contained herein actually
pertain to the treadle type brake valve. The treadle and
suspended type valves differ in that the suspended pedal
valve is turned over and the valve body is equipped with
an exhaust port at a 90 degree angle at the top to
exhaust air out the side of the cab.
Applying Normal Operation - Primary Circuit Portion
of Brake Valve (Fig. 3)
When the brake pedal is depressed, the plunger exerts
force on the spring seat, rubber graduating spring and
primary piston. The primary piston which contains the
exhaust valve seat, closes the primary exhaust valve. As
the exhaust valve closes, the primary inlet valve is
moved off its seat allowing primary air pressure to flow
out the primary delivery port.
Fig. 2 Suspended Type Brake Valve
CTS-4079 CHAPTER IV
PRINTED IN UNITED STATES OF AMERICA