BENDIX SD-03-818 User Manual
Bendix® E-7™ Dual Brake Valve
SD-03-818
SECONDARY
DELIVERY
SECONDARY
SUPPLY
PRIMARY
SUPPLY
PRIMARY
DELIVERY
MOUNTING
PLATE
SECONDARY
DELIVERY
SECONDARY
SUPPLY
SECONDARY
DELIVERY
PRIMARY
DELIVERY
PRIMARY
SUPPLY
FIGURE 1 - E-7
™
DUAL BRAKE VALVE
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
applying and re leasing the vehicle brakes.
™
The circuits in the E-7
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.
dual brake valve are identifi ed as
The primary circuit portion of the valve 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 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.
1
OPERATION
BALANCED: SECONDARY CIRCUIT PORTION
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 fl ow 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
valve closes, the secondary inlet valve is moved off its seat
allowing secondary air pressure to fl ow 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.
APPLYING: LOSS OF AIR IN PRIMARY CIRCUIT
Should air be lost in the primary circuit, the function will
be as follows: As the brake pedal is depressed and no air
pressure is present in the primary circuit supply and delivery
ports, the primary piston will mechanically move the relay
piston allowing the piston to close the secondary exhaust
valve and open the secondary inlet valve and allow air
pressure to fl ow out the delivery port.
When the air pressure on the secondary side of the relay
piston approaches that being delivered on the primary
side of the relay piston, the relay piston moves closing
the secondary inlet valve and stopping further fl ow of
air pressure from the supply line through the valve. The
exhaust remains closed as the pressures balance.
When applications in the graduating range are made, a
balanced position in the primary portion is reached as
the air pressure on the delivery side of the primary piston
equals the effort exerted by the driver’s foot on the pedal.
A balanced position in the secondary portion is reached
when air pressure on the secondary side of the relay piston
closely approaches the air pressure on the primary side
of the relay piston.
When the brake pedal is fully depressed, both primary
and secondary inlet valves remain open and full reservoir
pressure is delivered out the delivery ports.
RELEASING: PRIMARY CIRCUIT PORTION
With the brake pedal released, mechanical force is
removed from the spring seat, rubber graduating spring,
and primary piston. Air pressure and spring load moves the
primary piston, opening the primary exhaust valve allowing
air pressure in the primary delivery line to exhaust out the
exhaust port.
RELEASING: SECONDARY CIRCUIT PORTION
With the brake pedal released, air is exhausted from the
primary side of the relay piston. Air pressure and spring
load move the relay piston, opening the secondary exhaust
valve allowing air pressure in the secondary delivery line
to exhaust out the exhaust port.
PREVENTIVE MAINTENANCE
Important: Review the Bendix Warranty Policy before
performing any intrusive maintenance procedures. A
warranty may be voided if intrusive maintenance is
performed during the warranty period.
BALANCED: PRIMARY CIRCUIT PORTION
When air pressure delivered to the brake actuators and air
pressure in the cavity on the delivery side of the primary
piston equals the mechanical force of the brake pedal
application, the primary piston will move and the primary
inlet valve will close, stopping the further fl ow of air from
the primary supply line through the valve. The exhaust
valve remains closed preventing any escape of air through
the exhaust port.
2
No two vehicles operate under identical conditions, as a
result, maintenance intervals may vary . Vehicles operating
in extreme duty commercial vocations, such as refuse and
transit, may experience accelerated wear of brake pedal
components when the recommended routine maintenance
is not performed. The wear may be compounded with the
use of high-offset brake pedals that increase the side-load
forces into the pedal assembly. Experience is a valuable
guide to determining the best maintenance interval for air
brake components. At a minimum, the E-7™ valve should
be inspected every 6 months or 1500 operating hours,
whichever comes fi rst, for proper operation. Should the
EXHAUST CHECK
VALVE
INLET-EXHAUST
ASSEMBLY (1)
RETAINER (17)
SCREW (21)
WASHER (22)
DIAPHRAGM (13)
PISTON SPRING (8)
RETAINER (20)
O-RING (7)
O-RING (6)
RETAINER (18)
RUBBER SPRING (10)
RUBBER SPRING SEAT (19)
O-RING (2)
O-RING (3)
RELAY SPRING (5)
INLET-EXHAUST
ASSEMBLY (4)
O-RING (11)
O-RING (9)
O-RING (12)
SPRING SEAT NUT (16)
STEM SPRING (23)
SPRING SEAT (15)
LOCK NUT (14)
MANIFOLD*
*OPTIONAL MANIFOLD FOR INSTALLATIONS
REQUIRING SUPPLY & DELIVERY LINE
CONNECTIONS ON ENGINE SIDE OF ENGINE
COMPARTMENT BULKHEAD.
PLUNGER FULCRUM PIN
ROLLER
SEALING
RINGS
STOP BUTTON
PEDAL
FIGURE 2 - E-7™ DUAL BRAKE VALVE
3
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