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| Illustration 1 | g02688219 |
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| Illustration 2 | g01446756 |
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Components of the service brake (1) Brake anchor (2) Plates (five) (3) Chamber (4) Springs (six) (5) Discs (four) (6) Guides (six) (7) Brake hub (8) Piston (9) Thrust washer | |
The disc brakes are positioned at all four of the interfaces between the spindles and axle housings. The heat from the friction of the brakes is removed by the oil in the compartment for the service brake.
Brake anchor (1) is fastened between the spindle and the axle housing. The brake anchor does not turn. The splines on the outside circumference of plates (2) engage with the splines which are positioned on the inside of the brake anchor.
There are splines on the outside circumference of brake hub (7). These splines engage with the splines on the inside circumference of discs (5). This action causes both the brake hub and the discs to turn together.
Oil pressure flows from the brake control valve into chamber (3) when a brake pedal is pushed. The oil in chamber (3) pushes piston (8) against plates (2) and against discs (5). This causes friction between plates (2). The plates are held stationary by anchor (1) and by discs (5), which turn with the rotation of the axle shafts. This friction causes the wheels to turn at a slower rate or to stop.
The discs have grooves which allow cooling oil to pass between the plates and the discs. These grooves allow the oil to flow in either the activated position or the released position. If the depth of the grooves in the friction discs is adequate, the cooling oil constantly flows between the discs and the plates. This process happens even when the service brakes are applied.
The oil from chamber (3) flows back to the service brake control valve, and to the hydraulic tank when the brake pedal is released. Springs (4) pull piston (8) away from the plates. The flow of oil between the plates and the discs helps to separate the stack as the brake is released.