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BENDIX AH-4 AIR HYD INTENSIFIER Manual
BENDIX AH-4 AIR HYD INTENSIFIER Manual

BENDIX AH-4 AIR HYD INTENSIFIER Manual

Air hydraulic intensifier

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®
®
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.
1

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Summary of Contents for BENDIX AH-4 AIR HYD INTENSIFIER

  • Page 1 ® ® ™ 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;...
  • Page 2: Removal From Vehicle

    3. Observe the stroke warning light. If the master cylinder 2. In the case of remote mounted reservoir, reconnect the piston seal leaks, the master cylinder, under sustained reservoir to the master cylinder. pressure, will slowly stroke until the stroke warning switch ™...
  • Page 3 DISASSEMBLY DISASSEMBLY Rotochamber from Master Cylinder FIGURE 1 Master Cylinder FIGURE 2 1. Clean exterior of master cylinder and drain any 1. Remove four cap screws (1), and remove the master remaining fluid, In the case of remote mounted reservoir, cylinder from the rotochamber.
  • Page 4 3/8 X 18 BOLT 3-1/8 C.R.S. 4-5/8 4-5/8 FIGURE 3 ASSEMBLY FIGURE 4 Rotochamber 1. Position the diaphragm on end in the inner diaphragm clamp (Fig. 1). The smaller diameter end of the diaphragm should be against the diaphragm clamp. 2.
  • Page 5 3. Install the new o-ring (2) on the cap nut after lubricating 7. With piston still depressed, install compensating spring with the fluid to be used in the master cylinder or Dow (11 ) and compensating valve (3). Set adapter block (or Corning 55-M pneumatic grease.
  • Page 6 ™ vehicle. If the vehicle is equipped with an AD-IS air dryer system or a dryer reservoir module, be sure to drain the purge reservoir. BW1455 © 2004 Bendix Commercial Vehicle Systems LLC. All rights reserved. 4/2004 Printed in U.S.A.

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Ah-4