BENDIX AH-4 Manual

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Bendix

AH-4

Air Hydraulic Intensifier

DESCRIPTION

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The AH-4

is an air-over-hydraulic intensifier available with

pressure ratios of 13.5 to 1, 17 to 1 and 23.5 to 1. The air

chamber is a rotochamber, either type 30, 36 or 50. The

master cylinder design is identical in all units; however, the

master cylinder is available with seals for hydraulic brake

fluid, or for mineral oil. The master cylinder displaces 6 cubic

inches with the type 36 or type 50 actuator and 4.6 cubic

inches with the type 30.

The type 30 unit is designed for dusty operation, as in off-

highway, with the non-pressure cavity protected by a tight

fitting head and a filter for breathing non-pressure air.

The master cylinder may have a remote or direct mounted

reservoir. Fig. 1 shows a 23.5 to 1 unit with integral reservoir.

OPERATION

The AH-4

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intensifier is normally used to provide hydraulic

pressure to hydraulic disc brakes on an air braked vehicle.

It may be used in any application where it is desired to

"intensify" available air pressure to a higher hydraulic

pressure. 100 psi air pressure introduced to the center port

at the rear of the rotochamber will produce approximately

1,350 psi hydraulic pressure at the master cylinder delivery

port with a type 30 rotochamber, 1,700 psi with a type 36

rotochamber, and approximately 2,350 psi with a type 50

rotochamber.

PREVENTIVE MAINTENANCE

Important: Review the warranty policy before performing

any intrusive maintenance procedures. An extended warranty

may be voided if intrusive maintenance is performed during

this period.

Because no two vehicles operate under identical conditions,

maintenance intervals will vary. Experience is a valuable guide

in determining the best maintenance interval for a vehicle.

Every Month, After 8,000 Miles, or 300 Operating Hours

1. Remove the cover and gasket from the brake fluid

reservoir, taking extreme care to first remove all dirt and

foreign material so that no foreign material is permitted

to get into the hydraulic fluid. If the fluid lever is low,

proper fluid should be added. CAUTION - The cover and

gasket will each indicate whether hydraulic brake fluid

or mineral oil should be added. The gasket for brake

fluid is black and the gasket for mineral oil is green.

2. Check the stroke warning switch by grasping the switch

extension rod underneath the rubber boot and pulling

firmly. With the ignition turned on, the warning light in

the cab should light. NOTE: If the warning light comes

on during a service application, the vehicle should be

brought in for service immediately.

3. Check tightness of mounting nuts, air and hydraulic

fittings.

Every 12 Months, 100,000 Miles, or 3,600 Operating Hours

1. Disassemble and clean all parts.

2. Install new rotochamber diaphragm, reservoir gasket,

seals or any parts worn or damaged.

OPERATING AND LEAKAGE TESTS

Operating Test

1. With the air system built up to governor cut-out pressure,

make and hold a full brake application. Hold for at least

5 minutes. Check the rear of the rotochamber and the

rotochamber head vents for air leakage by coating with

a soap solution.

2. While still holding the brake application, check for

hydraulic fluid leaks at all fitting connections and at the

disc brake calipers.