Valves are the vital
controlling mechanisms of air brake systems. Over the decades, Bendix has developed a wide
range of valves to distribute and apply pressurized air throughout the braking system.
From this page of the AlliedSignal Truck Brake Systems Web site you can find the
following information:
E-6 and E-10 Brake Valves
The E-6 and E-10 Dual Brake Valves are floor mounted, treadle operated brake valves
with two separate supply and delivery circuits. These brake valves provide the driver with
graduated control for applying and releasing the vehicle brakes.
E-10 and E-6 brake valves differ in the spring configuration in the upper body. A metal
coil spring is used in the E-10 brake valve for gentler applications in passenger
vehicles. A rubber spring provides the driver with a less sensitive "feel" on
the E-6.
Facts About Dual Circuit Brake Valves
Dual circuit brake valves use two separate supply and delivery circuits, each of which
handle both service and secondary braking. Typically, the service ("number one"
or "primary") brake circuit supplies pressure to the rear brakes, and the
secondary (or "number two") brake circuit supplies the front brakes.
The service circuit is mechanically operated through the action of the treadle/pedal
and plunger. The secondary circuit normally operates similar to a relay valve, with
control air delivered from the number one primary circuit. In the emergency mode (failure
of the primary supply), the secondary inlet valve is mechanically opened by push-through
force from the driver’s foot via the treadle/pedal, plunger and primary piston.
The E-6, E-10, E-12 and E-15 dual brake valves are floor mounted, treadle operated
valves with two separate supply and delivery circuits.
The E-7 and E-14 dual brake valves are designed for mounting on the engine compartment
bulkhead. These suspended pedal valves also feature two separate supply and delivery
circuits, located at the back of the valve. For engine-side firewall connections, an
optional manifold is available.
Some Features:
- Dual brake valves typically have 2-3 psi differential between primary (#1) and secondary
(#2) delivery circuits.
- The E-10, primarily for bus applications, utilizes a metal, instead of rubber, coil
spring to enhance the ability to make gradual brake applications.
- E-7 Brake valve has cartridge maintenance feature.
Push-Pull (PP) Dash Mounted Valves
PP valves are push-pull, hand-operated on-off air control valves with an exhaust
function. Most are pressure sensitive, so that they will automatically move from the
applied to the exhaust position as supply pressure is reduced to a certain minimum.
Sensitivity varies depending on the spring installed.
R-12 and R-14 Relay Valves
Relay valves function as remotely controlled brake valves to speed up the application
and release of the brakes. A relay valve is normally mounted near the chambers it serves.
The R-14 is similar to the R-12 but incorporates a quick release and anti-compounding
feature located above its horizontal service port. Anti-compounding is a safety feature
which prevents both the service and spring brakes from being applied at the same time,
which could create high enough pressures to damage the braking mechanism.
Other specialized
relay valves include the BP-R1 bobtail proportioning valve which improves braking
performance for unloaded tractors, and the R-12P (above) which reinforces and equalizes
the control signal on long non-towing trailers, towing trailers and dollies. Our newest
relay valve is the R-12DC (right), which is used on straight trucks and buses and has a
built-in biased double-check valve.
