Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.
Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.
Dispose of all fluids according to local regulations and mandates.
Do not engage the parking brake while the machine is moving unless the primary service brake fails. The use of the parking brake as a service brake in regular operation will cause severe damage to the parking brake system.
View of Output Side of Transmission
(1) Parking brake
(2) Air inlet to parking brake
(3) Outer plug
Parking brake (1) is located on the transmission output shaft. The parking brake is engaged by spring pressure. Pressure air releases the parking brake. The parking brake includes outer plug (3) , which can be removed in order to access the inner plug (not shown). When the outer plug is removed, the small amount of oil should be drained into a suitable container. Remove the inner plug in order to drain moisture from the machine air system.
View of the console to the right of the seat
Air from the air control valve for the service brakes flows through the check valve for the parking brake. Depress the transmission control (lever) (4) and move the transmission control (lever) backward. This procedure allows pressure air to flow through the air control valve for the parking brake.
Then, air flows through a junction block and into parking brake (1) at air inlet (2) , which is on the transmission flange. This flow of air disengages the parking brake.
Section View of Parking Brake
(5) Brake housing
(7) Transmission output shaft
(10) Air chamber
(12) Transmission cover
The parking brake consists of several components. Hub (14) is connected to transmission output shaft (7) . Discs (6) are splined to hub (14) . Plates (11) are held stationary by dowels (13) , which are inserted into transmission cover (12) and into brake housing (5) . Brake housing (5) is bolted to transmission cover (12) . Piston (15) provides a passage for the flow of air to air chamber (10) in order to activate piston (8) . This activation releases the parking brake when lever (4) is moved from the PARKING BRAKE ENGAGED position. Springs (9) provide clamping force across the brake pack in order to engage the parking brake when air chamber (10) is depressurized.
When transmission control (lever) (4) is in the PARKING BRAKE ENGAGED position, pressure air is not available to air chamber (10) . Springs (9) force piston (8) so that the piston contacts plates (11) and discs (6) . Piston (8) forces the plates and the discs against transmission cover (12) . Springs (9) generate enough force in order to create sufficient friction between plates (11) and discs (6) so that the discs stop spinning. Since the discs are splined to hub (14) and the hub is connected to transmission output shaft (7) , the transmission output shaft does not turn. When transmission control (lever) (4) is in the PARKING BRAKE ENGAGED position or air chamber (10) is depressurized, the machine cannot move.
When the machine is stopped and transmission control (lever) (4) is pushed into the PARKING BRAKE ENGAGED position, the transmission remains in the NEUTRAL position.
When transmission control (lever) (4) is in any of the following positions: the NEUTRAL position, any of the FORWARD positions and any of the REVERSE positions, then the parking brake is in the OFF position, and air is pressurized within air chamber (10) . Pressure air then forces piston (8) against springs (9) . The clamping force across the brake pack is eliminated. Discs (6) are allowed to rotate freely with hub (14) and with transmission output shaft (7) .