554 and 574 Forwarders Power Train Caterpillar

The parking brake and the service brake are engaged or disengaged with the brake cylinder. Each axle has two brake cylinders. The parking brake is applied with spring pressure and released with pressure oil. The service brake is engaged with pressure oil.

The parking brake and the service brake may not engage correctly if the stroke of the brake cylinder is set incorrectly. Be sure to set the stroke of the brake cylinder when the brake cylinder is replaced.

Illustration 1	g00923728
(1) Plug (oil filler). (2) Power train oil dipstick. (3) Plug (brake wear). (4) Plug (breather and brake wear). (5) Brake cylinders.

Test Procedure

Illustration 2	g00524342
Brake Cylinder (6) Cap. (7) Bolt (parking brake release). (8) O-ring seal. (9) Upper housing. (10) Piston. (11) Bolt. (12) Adjusting bolt. (13) Adjusting nut. (14) O-ring seal. (15) Parking brake cylinder. (16) Lower housing. (17) Pressure piston. (18) Service brake cylinder.

The stroke of the brake cylinder can be tested on a bench or on the machine.

1. Place wheel chocks in front of the tires and behind the tires in order to ensure that the machine will not move.

2. Remove cap (6) and remove bolt (7) .

3. Engage the parking brake.

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Illustration 3	g00581121
Brake Cylinder

4. Measure distance (A) through the threaded hole of piston (10) and then record distance (A). Use a depth gauge or dial indicator to measure distance (A) .

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Illustration 4	g00524518
Brake Cylinder (19) Bolt. (20) Purge valve (parking brake). (21) Port (parking brake). (22) Purge valve (service brake). (23) Port (service brake).

5. Release the parking brake.

   If you are performing this test with the brake cylinder in the axle, release the parking brake. The parking brake can be released by placing the parking brake switch in the ON position and slowly depressing the accelerator pedal until the machine barely starts to move.

   When the brake cylinder is removed from the axle and you are performing this test, release the parking brake with air pressure at port (21) .

6. Measure distance (B) through the threaded hole of piston (10) and record distance (B) .

   A - B = Cylinder stroke

   Cylinder stroke ... 5.0 to 6.0 mm (.197 to .236 inch)

7. If the stroke of the brake cylinder is out-of-range perform the following adjustment procedures.

Adjustment Procedure

Note: Adjust the cylinder stroke of the left brake and the right brake separately.

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Illustration 5	g00683537
Brake Cylinder (7) Bolt (parking brake release). (19) Bolts.

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Illustration 6	g00683488
Brake Cylinder (no upper housing) (12) Adjusting bolt. (13) Adjusting nut.

1. Use bolt (7) to release the parking brake.

2. Loosen four bolts (19) and remove the upper housing (9) .

   Note: Do not loosen two bolts (11) .

3. Loosen adjusting nut (13). In order to loosen adjusting nut (13), pressure piston (17) must be secured.

4. Remove bolt (12). Be sure to clean all the dirt and the oil from the threads of bolt (12) and adjusting nut (13) .

5. Screw on adjusting nut (13) up to the head of bolt (12) .

6. Apply 9S-3263 Thread Lock Compound to the threaded portion of bolt (12) .

7. Screw bolt (12) into pressure piston (17) .

   Torque for bolt (12) ... 8 to 15 N·m (6 to 11 lb ft)

   The brake disc and the ball and ramp mechanism are now next to each other without an air gap.

8. Turn back bolt (12) about 3 1/2 revolutions (approximately 5.25 mm (.200 inch)) and lock bolt (12) into position with locking nut (13) .

   While you are adjusting bolt (12), secure pressure piston (17) .

   An air gap of 2.4 mm (.095 inch) results from this adjustment.

   Torque for bolt (12) ... 8 to 15 N·m (6 to 11 lb ft)

   Note: Remove any residue of the thread lock compound that is on cylinder (16) (bottom portion) or pressure piston (17) .

9. Measure the stroke of pressure piston (17) while the brake is activated and deactivated. The stroke of pressure piston (17) determines the air gap between the brake discs. If the stroke of pressure piston (17) exceeds 5.25 mm (.200 inch) repeat Steps 1 through 9.

10. Insert O-ring (14) into the groove of cylinder (16) .

11. Install cylinder (15) onto brake cylinder (18) with four bolts (19) .

    Torque for four bolts (19) ... 45 N·m (33 lb ft)

    Note: When spring loaded cylinder (15) is fastened to brake cylinder (18) and bolt (7) is removed, the brake is in the brake position.

12. Insert O-ring (8) into spring loaded cylinder (15). Place bolt (7) into cap (6) and tighten cap (6) onto spring loaded cylinder (15) .