1
®
SD-03-818
Bendix
®
E-7
™
Dual Brake Valve
valve closes, the secondary inlet valve is moved off its seat
allowing secondary air pressure to flow out the delivery port.
Because of the small volume of air required to move the
relay piston, action of the secondary circuit portion of the
valve is almost simultaneous with the primary circuit
portion.
APPLYING: LOSS OF AIR IN SECONDARY
CIRCUIT
Should air be lost in the secondary circuit, the primary
circuit portion will continue to function as described above
under Normal Operation: Primary Circuit Portion.
DESCRIPTION
The Bendix
®
E-7
™
dual brake valve is a suspended,
pedal-operated type brake valve with two separate supply
and delivery circuits for service and emergency braking,
which provides the driver with a graduated control for apply-
ing and releasing the vehicle brakes.
The circuits in the E-7
™
dual brake valve are identified as
follows: The primary circuit portion is that portion of the valve
between the spring seat which contacts the plunger and the
relay piston; the secondary circuit portion is that portion
between the relay piston and the exhaust cavity.
The primary circuit portion of the valve is similar in operation
to a standard single-circuit air brake valve, and under nor-
mal operating conditions the secondary circuit portion is
similar in operation to a relay valve.
The primary circuit portion of the valve is part of a removable
cage which also houses the relay piston and the cage which
can be removed without removing the entire brake valve.
Both primary and secondary circuit portions of the E-7
™
dual brake valve use a common exhaust protected by an
exhaust check valve.
OPERATION
APPLYING: NORMAL OPERATION - PRIMARY
CIRCUIT PORTION
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 delivery port.
APPLYING: NORMAL OPERATION -
SECONDARY CIRCUIT PORTION
When the primary inlet valve is moved off its seat, air is
permitted to pass through the bleed passage and enters the
relay cavity. The air pressure moves the relay piston, and
the relay piston, which contains the exhaust seat, closes
the secondary exhaust valve. As the secondary exhaust
SECONDARY
DELIVERY
PRIMARY
DELIVERY
PRIMARY
SUPPLY
SECONDARY
SUPPLY
MOUNTING
PLATE
FIGURE 1 - E-7
™
DUAL BRAKE VALVE
