854K Wheel Dozer Caterpillar

Illustration 1	g06235620
(A) Front Service Brake Accumulator (B) Rear Service Brake Accumulator

Illustration 2	g00428660
Brake accumulator (1) Nitrogen charging valve (2) Accumulator (3) Chamber (4) Piston (5) Pressure oil chamber (6) Outlet to the service brake control valve

Piston (4) moves up and down inside the bore of each accumulator (2). Chamber (3) has a charge of approximately 5516 kPa (800 psi) of dry nitrogen gas. Each accumulator is charged with nitrogen through charging valve (1).

Oil enters pressure oil chamber (5) from the brake pump. The oil reaches the pressure oil chamber through outlet port (6). The oil pushes piston (4) upward. The pressure of the oil compresses the nitrogen gas.

When the pressure in the accumulators reaches approximately 13790 ± 345 kPa (2000 ± 50 psi), the supply of oil is stopped. When either brake pedal is pushed, oil from pressure oil chamber (5) flows out of port (6) to the service brake control valve. This action applies the service brakes.