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| Illustration 1 | g00471812 |
Location of Components for Service Brakes (1) Spindle. (2) Brake discs. (3) Plates. (4) Piston. (5) Chamber. (6) Hub. (7) Guides. (8) Springs. (9) Axle housing. | |
The machine has disc brakes at all four wheels. The brakes are activated by oil. The heat from friction of the brakes is removed by the oil in the axle housing.
Spindle (1) is attached to axle housing (9), which does not turn. There are slots on the inside of spindle (1). Tabs on the outside circumference of plates (3) fit in the slots in spindle (1). Hub (6) has splines on the outside circumference which fit in the splines on the inside circumference of brake discs (2). Both a wheel assembly, which is attached to spindle (1), and brake discs (2) turn together.
When the operator applies the service brakes, pressurized oil flows from the brake control valve and into chamber (5), which is located behind piston (4). Oil in chamber (5) pushes piston (4) against plates (3) and brake discs (2). This causes friction between plates (3). The plates are held stationary by spindle (1), and brake discs (2), which turn with the rotation of the wheels. The friction from brake discs (2) causes wheel rotation to slow down. When the friction is great enough, the wheels will stop rotating. The amount of brake application is determined by the position of the brake pedal.
Grooves are cut in the faces of brake discs (2). These grooves permit the passage of cooling oil between plates (3) and brake discs (2). When the service brakes are in the engaged position or in the disengaged position, cooling oil passes between plates (3) and brake discs (2). When brake discs (2) have adequate groove depth, cooling oil will continuously flow between brake discs (2) and plates (3) .
When the brake pedal is released, oil from chamber (5) flows back through the brake control valve and to the tank. Guides (7) and springs (8) pull piston (4) away from plates (3). The flow of oil between plates (3) and brake discs (2) helps to separate the stack as the service brakes are released.
The service brakes can be actuated by either the left brake pedal or by the right brake pedal. When the transmission neutralizer override switch is moved to the UNLOCKED position, both of the brake pedals apply the service brakes. However, only the left pedal may be used to neutralize the transmission. This allows the full engine power to be used in the hydraulic system.
Reference: For more information on the function of the transmission neutralizer, refer to Systems Operation, "Limit Switch (Transmission Neutralizer)".
If the machine loses power, or if the hydraulic pump fails, the service brakes can still be applied. The pressure in the nitrogen charged accumulators for the service brakes allows several applications of the brake pedals. This is for stopping the machine or for slowing the machine enough to engage the parking brake.