Preventive Maintenance, Operating Test | BENDIX SD-11-1357 instruction

SD-11-1357

Bendix® AH-4™Air Hydraulic Intensifier

DESCRIPTION

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™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.