Bendix Bw1455 Users Manual Sd111357

Bendix-Sd-11-1357-Users-Manual-682580 bendix-sd-11-1357-users-manual-682580

2015-03-12

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Bendix® AH-4™ Air Hydraulic Intensifier

SD-11-1357

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.

OUTER DIAPHRAGM

CLAMP

FIGURE 1

DIAPHRAGM

GUIDE

STROKE WARNING SWITCH

FILTER

3. Observe the stroke warning light. If the master cylinder

piston seal leaks, the master cylinder, under sustained

pressure, will slowly stroke until the stroke warning switch

is activated.

REMOVAL FROM VEHICLE

1. Disconnect the hydraulic line from the delivery port of

the master cylinder and allow the hydraulic fluid to drain

into a suitable receptacle. The drainage may be

expedited by removing the reservoir cover and gasket.

2. Disconnect the air line from the rotochamber, the fluid

supply line from the master cylinder (in the case of

remote mounted reservoirs), and the electrical

connections from the stroke warning switch mounted in

the head of the rotochamber.

3. Remove the nuts from the studs which hold the mounting

brackets and remove the AH-4™ intensifier from the

vehicle.

INSTALLING ON VEHICLE

1. Remount the AH-4™ intensifier, reconnect the air delivery

line to the rotochamber and the electrical connections

to the stroke warning switch.

2. In the case of remote mounted reservoir, reconnect the

reservoir to the master cylinder.

3. Before adding hydraulic fluid, cycle the AH-4™ intensifier

very carefully by making a very light brake application.

The rotochamber should extend to full stroke and operate

the stroke warning switch, causing the warning light to

come on in the cab. This will test the stroke warning

system. Release the application and reset the stroke

warning switch.

4. Remove plugs, reconnect the fluid lines and bleed the

master cylinder. The master cylinder itself may be bled

by gravity by filling the reservoir and opening the bleeder

fitting opposite the discharge port. When clear fluid flows

from the bleeder fitting, it may be closed. If the rest of

the system needs bleeding, it may be done by opening

the appropriate bleed fitting and cycling the AH-4™

intensifier. Hydraulic brake fluid equivalent to DOT 3

specifications should always be used. Some AH-4™

intensifier units are designed to be used with mineral

oil, in which case, the reservoir cover will clearly so

designate. Rubber parts for use with mineral oil are color

coded. Reservoir gasket diaphragm is green, seals and

o-rings are brown.

TERMINAL PER SAE

1858 2 - PLACES PUSH TO RESET

2.45

PUSH PLATE

PUSH ROD

INNER

DIAPHRAGM

CLAMP

DIAPHRAGM

FIGURE 2

3.19 MAX

.60

.74

3.12 REF

STROKE

DISASSEMBLY

Rotochamber from Master Cylinder FIGURE 1

1. Remove four cap screws (1), and remove the master

cylinder from the rotochamber.

Rotochamber

1. Remove the Gap screws (2) which hold the rotochamber

head in the shell and remove the head (6), return spring

(7), and spring guide (8).

2. Remove the nuts (3) from the body which secure the

outer clamp (4) to the body. On some units, one of the

mounting brackets is also retained by three of these

nuts.

3. Place body, open end down on bench and tap the ends

of the studs (5) with a brass drift, lead or plastic hammer.

The studs should be tapped on one side of the air inlet

and then the other alternately, to free the outer clamp.

4. Grasp the push rod and, by pulling and wiggling the

entire assembly consisting of push rod and plate,

diaphragm guide, diaphragm, inner and outer clamps

should ease out of the body.

5. Remove the outer clamp.

6. Remove nuts from inside of diaphragm guide.

7. Disassemble the inner diaphragm clamp, diaphragm,

push plate rod assembly, and diaphragm guide.

8. Remove the stroke warning switch from the rotochamber

head and bench test for electrical integrity. If OK, replace

in head.

DISASSEMBLY

Master Cylinder FIGURE 2

1. Clean exterior of master cylinder and drain any

remaining fluid, In the case of remote mounted reservoir,

drain and clean the reservoir.

2. Secure master cylinder in a vise. Depress piston (1)

Fig. 2, at least 1/2 in. and hold. This may be done with

a simple tool as shown in Figs. 3 and 4. Remove the

four self-threading bolts (9) securing the adapter block

or the reservoir to the master cylinder. Remove the

adapter block or reservoir and the compensating valve

(3) and spring (11).

CAUTION The compensating valve must be removed

before any attempt is made to remove the hydraulic

piston assembly (see Fig. 5).

3. Remove retaining ring (8) and stop washer (7).

4. Remove piston holding tool and remove piston (1) and

spring (4).

5. Remove cap nut (10) from adapter block. Remove o-ring

(2) from cap nut and compensating valve seal (5) from

adapter block or reservoir.

FIGURE 3

FIGURE 4

FIGURE 5

ASSEMBLY

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. Place and install the diaphragm guide within the

diaphragm and over the inner diaphragm clamp studs.

3. Install the push plate push rod assembly within the

diaphragm guide and over the inner diaphragm clamp

studs.

4. Install nuts on the inner diaphragm clamp studs and

tighten securely (55-70 inch pounds)

5. Place the assembly consisting of the push rod, push

plate, diaphragm guide, diaphragm, and inner clamp

inside of the outer clamp.

6. Roll the free end of the diaphragm back and over the

end of the outer diaphragm clamp.

7. Lubricate the inside wall of the body and the rolled

surface of the diaphragm with BW652M Type 2.

8. Slide the above assembly into the body. The end of the

diaphragm should fit snugly against the shoulder in the

body. Position the outer diaphragm clamp studs through

the holes at the end of the body, install nuts and tighten

securely. Torque to 100-125 inch pounds.

9. Install spring guide, and install spring over push rod.

10. Install cover over push rod and into body. Attach cover

to body with cap screws, tightening securely. Torque to

110-150 inch pounds.

ASSEMBLY

Master Cylinder

1. Wash the cap nut, adapter block, and cylinder castings

with alcohol or mineral spirits and dry thoroughly.

2. Carefully clean the filter screen. (6)

Continued on Page 5.

3/8 X 18 BOLT

3-1/8

4-5/8

C.R.S.

FIGURE 7

FIGURE 6

FIGURE 8

FIGURE 9

3. Install the new o-ring (2) on the cap nut after lubricating

with the fluid to be used in the master cylinder or Dow

Corning 55-M pneumatic grease. Thread the cap nut in

the adapter block and torque to 300 inch pounds.

4. Coat the new compensating seal (5) with fluid or Dow

Corning 55-M pneumatic grease and install in mating

grooves in bottom of adapter block or reservoir.

5. Coat bore in master cylinder with fluid to be used, place

spring (4) in piston assembly (1 ) and slide both into

bore of master cylinder (fig. 6).

6. Place the stop washer (7) and retaining ring (8) over the

center post of the retaining tool, depress the piston (1)

(see Fig. 7). Make certain the retaining ring is properly

seated in its corresponding groove in the master cylinder

casting (see Fig. 8). CAUTION - Keep retaining tool

in place until step 8 is completed!!

7. With piston still depressed, install compensating spring

(11 ) and compensating valve (3). Set adapter block (or

reservoir) in place. The master cylinder casting should

preferably be held in a horizontal position for this

operation. Start the four self-threading bolts (9) by hand

to prevent cross threading and torque to 150- 200 inch

pounds. Care should be taken that the compensating

valve is properly located before the adapter block

or reservoir is located and snugged down (Fig. 9).

The piston may now be released by removing the

retaining tool.

8. A simple check may be made to determine that the

compensating valve is properly installed. Apply air

pressure on the discharge port of the master cylinder.

With the piston released, air should back flow through

the compensating valve and out the adapter fitting or

reservoir. Depress the piston at least 1/4 in. Air pressure

should now be trapped in the master cylinder and there

should be no evidence of back flow out the adapter

block or reservoir.

CAUTION - 50 psi air pressure will create approximately

100 pounds of additional reactive force on the piston.

The piston retaining tool should, therefore, be used for

this test.

9. Install the master cylinder on the rotochamber with four

3/8 in. cap screws torqued to 300 inch pounds.

WARNING! PLEASE READ AND FOLLOW THESE

INSTRUCTIONS TO AVOID PERSONAL INJURY

OR DEATH:

When working on or around a vehicle, the following

general precautions should be observed at all times.

1. Park the vehicle on a level surface, apply the

parking brakes, and always block the wheels.

Always wear safety glasses.

2. Stop the engine and remove ignition key when

working under or around the vehicle. When

working in the engine compartment, the engine

should be shut off and the ignition key should be

removed. Where circumstances require that the

engine be in operation, EXTREME CAUTION should

be used to prevent personal injury resulting from

contact with moving, rotating, leaking, heated or

electrically charged components.

3. Do not attempt to install, remove, disassemble or

assemble a component until you have read and

thoroughly understand the recommended

procedures. Use only the proper tools and observe

all precautions pertaining to use of those tools.

4. If the work is being performed on the vehicle’s air

brake system, or any auxiliary pressurized air

systems, make certain to drain the air pressure from

all reservoirs before beginning ANY work on the

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.

5. Following the vehicle manufacturer’s

recommended procedures, deactivate the electrical

system in a manner that safely removes all

electrical power from the vehicle.

6. Never exceed manufacturer’s recommended

pressures.

7. Never connect or disconnect a hose or line

containing pressure; it may whip. Never remove a

component or plug unless you are certain all

system pressure has been depleted.

8. Use only genuine Bendix® replacement parts,

components and kits. Replacement hardware,

tubing, hose, fittings, etc. must be of equivalent

size, type and strength as original equipment and

be designed specifically for such applications and

systems.

9. Components with stripped threads or damaged

parts should be replaced rather than repaired. Do

not attempt repairs requiring machining or welding

unless specifically stated and approved by the

vehicle and component manufacturer.

10. Prior to returning the vehicle to service, make

certain all components and systems are restored to

their proper operating condition.

Bendix Bw1455 Users Manual Sd111357

Bendix-Sd-11-1357-Users-Manual-682580 bendix-sd-11-1357-users-manual-682580

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