Bendix Commercial Vehicle Systems E10P User Manual

Bendix® E-8P™ & E-10P™ Dual Brake Valves

TREADLE

SD-03-830

TREADLE

MOUNTING

PLATE

SUPPLY

DELIVERY

VALVE

AUXILIARY

EXHAUST

FIGURE 1 - E-8P™ DUAL BRAKE VALVE

SUPPLY

(4)

DESCRIPTION

Refer to Figures 4, 5 and 6 for item numbers referenced in parenthesis.

The Bendix dual brake valves are ﬂ oor mounted, treadle operated type brake valves with two separate supply and delivery circuits for service (primary and secondary) braking, which provides the driver with a graduated control for applying and releasing the vehicle brakes.

The E-10P E-8P™ dual brake valve except that a metal coil spring (5) housed in an upper body assembly replaces the rubber spring (27) used in the E-8P™ valve. The use of a metal coil spring (and the upper body assembly) provides greater treadle travel and, therefore, provides the driver with a less sensitive “feel” when making a brake application. The E-10P™ dual brake

E-8P™ (Figure 1) and E-10P™ (Figure 2)

™

dual brake valve (Figure 2) is similar to the

MOUNTING

PLATE

VALVE

SUPPLY

(4)

FIGURE 2 - E-10P

EXHAUST

™

DUAL BRAKE VALVE

DELIVERY

(4)

valve is generally used on buses, where smooth brake applications contribute to passenger comfort.

The circuits in the E-8P™/E-10P™ dual brake valves are identiﬁ ed as follows: The No. 1 or primary circuit is that portion of the valve between the spring seat which contacts the plunger and the relay piston; the No. 2 or secondary circuit is that portion between the relay piston and the exhaust cavity.

The primary circuit of the valve is similar in operation to a standard single circuit air brake valve and under normal operating conditions the secondary circuit is similar in operation to a relay valve.

Both primary and secondary circuits of the brake valve use a common exhaust protected by an exhaust diaphragm.

SLACK

ADJUSTER

GOVERNOR

TRAILER

CONTROL

VALVE

BRAKE

CHAMBER

(E-8P™ OR E-10P™)

DUAL BRAKE

VALVE

AIR DRYER

COMPRESSOR

™

MV-3

MANIFOLD

VALVE

SUPPLY

RESERVOIR

(WET T ANK)

PROTECTION VALVE

#1 SERVICE RESERVOIR

TP-5

™

TRACTOR

DOUBLE

CHECK

VALVE

#2 SERVICE RESERVOIR

SLACK

ADJUSTER

SPRING

BRAKES

QUICK

RELEASE

VALVE

™

BP-R1

BOBTAIL

PROPORTIONING

VALVE

FIGURE 3 - TYPICAL PIPING SCHEMATIC

SUP - 1

SUP - 2

UPPER BODY

DEL - 1

21 14

LOWER BODY

BODY A TT ACHING

SCREWS

DEL - 2

FIGURE 4 - E-8P

™

DUAL BRAKE VALVE SECTIONAL VIEW

EXHAUST COVER

ATTACHING SCREWS

OPERATION - Refer to Figure 3

BALANCED: NO. 2 OR SECONDARY CIRCUIT

APPLYING: NORMAL OPERATION - NO. 1 OR PRIMARY CIRCUIT PORTION

When the brake treadle is depressed, the plunger exerts force on the spring seat (26), graduating spring (23), and primary piston (22). 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 to ﬂ ow out the No. 1 or primary delivery port.

APPLYING: NORMAL OPERATION - NO. 2 OR SECONDARY CIRCUIT

When the primary inlet valve (33) is moved off its seat, air is permitted to pass through the bleed passage and enters the relay piston cavity. The air pressure moves the relay piston (20), which contains the exhaust seat, and closes the secondary exhaust valve. As the secondary exhaust valve closes, the inlet valve (13) is moved off its seat allowing the secondary air to ﬂ ow out the delivery of the same circuit. Because of the small volume of air required to move the relay piston (20), action of the secondary circuit of the valve is almost simultaneous with the primary circuit portion.

APPLYING: LOSS OF AIR IN THE NO. 2 OR SECONDARY CIRCUIT

Should air be lost in the No. 2 or secondary circuit, the No. 1 or primary circuit will continue to function as described above under Normal Operation: No. 1 or Primary Circuit Portion.

APPLYING: LOSS OF AIR IN THE NO. 1 OR PRIMARY CIRCUIT

Should air be lost in the primary circuit, the function will be as follows: As the brake treadle is depressed and no air pressure is present in the primary circuit supply and delivery ports, the primary piston (22) will mechanically move the relay piston (20), allowing the piston to close the secondary exhaust valve and open the secondary inlet valve and allow air to ﬂ ow out the secondary delivery port.

When the air pressure on the delivery side of the relay piston (20) 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 from the supply line through the valve. The exhaust remains closed as the secondary delivery pressure balances the primary delivery pressure.

When applications in the graduating range are made, a balanced position in the primary circuit is reached as the air pressure on the delivery side of the primary piston (22) equals the effort exerted by the driver’s foot on the treadle. A balanced position in the secondary portion is reached when air pressure on the secondary side of the relay piston (20) closely approaches the air pressure on the primary side of the relay piston.

When the brake treadle is fully depressed, both the primary and secondary inlet valves remain open and full reservoir pressure is delivered to the actuators.

RELEASING: NO. 1 OR PRIMARY CIRCUIT

With the brake treadle released, mechanical force is removed from the spring seat (26), graduating spring (23), and primary piston (22). 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: NO. 2 OR SECONDARY CIRCUIT

With the brake treadle released, air is exhausted from the primary circuit side of the relay piston (20). 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: NO. 1 OR PRIMARY CIRCUIT

When the primary delivery pressure acting on the primary piston (22) equals the mechanical force of the brake pedal application, the primary piston (22) will move and the primary inlet valve (33) will close, stopping 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.

No two vehicles operate under identical conditions, as a result, maintenance intervals may vary. Experience is a valuable guide in determining the best maintenance interval for air brake system components. At a minimum, the E-8P™ or E-10P™ valve should be inspected every 6 months or 1500 operating hours, whichever comes ﬁ rst, for proper operation. Should the E-8P™ or E-10P™ valve not meet the elements of the operational tests noted in this document, further investigation and service of the valve may be required.

Visually check for physical damage to the brake valve such as broken air lines and broken or missing parts.

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