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| Illustration 1 | g00834179 |
(A-B) Pressure taps for the service brakes. (C) Pressure taps for the accumulators. (1) Rear service brakes. (2) Front service brakes. (3) Position sensor (torque converter impeller clutch). (4) Stop light limit switch. (5) Service brake control valve. (7) Hydraulic oil filter. (8) Accumulators. (9) Parking brake. (10) Pilot relief valve. (11) Accumulator charging valve. (12) Pressure switch (brake accumulator). (13) Pump. (14) Breaker relief valve. (15) Parking brake control valve. (16) Pressure switch (parking brake oil). (18) Hydraulic tank. | |
Note: The 836G Landfill Compactor is not equipped with rear service brakes.
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| Illustration 2 | g00843539 |
836G Landfill Compactor Hydraulic Schematic (B) Pressure tap for the front service brakes. (C) Pressure tap for the accumulator. (1) Front service brakes. (3) Position sensor (torque converter impeller clutch). (4) Stop light limit switch. (5) Service brake control valve. (7) Hydraulic oil filter. (8) Accumulator. (9) Parking brake. (10) Pilot relief valve. (11) Accumulator charging valve. (12) Pressure switch (brake accumulator). (13) Pump. (14) Breaker relief valve. (15) Parking brake control valve. (16) Pressure switch (parking brake oil). (18) Hydraulic tank. | |
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| Illustration 3 | g00843560 |
834G Hydraulic Schematic (A) Pressure tap for the rear brakes. (B) Pressure tap for the front brakes. (C) Pressure taps for the accumulators. (1) Front service brakes. (2) Rear service brakes. (3) Position sensor (torque converter impeller clutch). (4) Stoplight switch. (5) Service brake control valve. (6) Temperature sensor. (7) Hydraulic oil filter. (8) Accumulators. (9) Parking brake. (10) Pilot relief valve. (11) Accumulator charging valve. (12) Pressure switch (brake accumulator). (13) Pump. (14) Breaker relief valve. (15) Parking brake control valve. (16) Pressure switch (parking brake oil). (18) Hydraulic tank. | |
Oil is sent from pump (13) through accumulator charging valve (11) into the oil end of the accumulators (8). A piston in the accumulator is held by dry nitrogen gas at a pressure of 5520 ± 350 kPa (800 ± 50 psi).
Oil flows into the accumulator in order to move the piston against the dry nitrogen. This compresses the dry nitrogen until the oil pressure reaches 1448 ± 345 kPa (2100 ± 50 psi). The oil also flows to the brake control valve (5) and to the pressure switch (12). The pressure switch will remain in the normally closed position. The low brake pressure indicator will remain illuminated until the oil reaches a pressure of 8960 ± 537 kPa (1300 ± 78 psi). This pressure is also sensed in accumulator charging valve (11) which stops the flow of oil to the accumulator.
A check valve in the accumulator charging valve prevents oil from flowing back through the charging valve. The flow control valve in the accumulator charging valve controls maximum oil pressure to the accumulator if the charging valve spool does not work correctly.
Brake control valve (5) is for the service brakes. Brake control valve (5) is in the circuit from the accumulator to the service brakes. When either brake pedal is pushed, oil from the accumulator flows to the brakes.
After the brakes have been applied several times, there is a smaller volume of oil in the accumulator. The piston in the accumulator moves toward the oil end until there is a decrease in oil pressure of approximately 2760 kPa (400 psi). The accumulator charging valve then permits oil from pump (13) to flow to accumulators (7) until the pressure again rises to 14500 ± 350 kPa (2100 ± 50 psi).
When either brake pedal is pushed, a spool in brake control valve (5) is moved. Oil from accumulators (8) flows to the service brakes. The heat from the friction of the brakes is removed by the oil in the final drive housing.
Parking brake (9) is spring applied and pressure released.
Control valve (15) is for the parking brake. When the parking brake is applied, oil from the accumulator is prevented from flowing to parking brake (9). This will allow the internal springs in parking brake (9) to apply the parking brake.
When parking brake control valve (15) is moved to the release position, oil from the accumulator flows through parking brake control valve (15) to parking brake (9) in order to release the parking brake.
Note: The 834G has two accumulators. Oil from the accumulator for the rear axle brakes flows through parking brake control valve (15) to parking brake (9) in order to release the parking brake.
Pressure switch (16) will illuminate the parking brake indicator when the pressure falls below 6890 kPa (1000 psi). Pressure switch (16) will not illuminate the parking brake indicator when the oil pressure rises above 8270 kPa (1200 psi).
Accumulator charging valve (11) provides pilot oil to the steering system. The pilot oil for the steering system also flows through hydraulic oil filter (7).