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| Illustration 1 | g06111154 |
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(1) Hydraulic tank & filters
(2) Foot brake control group (3) Service brake control valve (4) Parking brake actuator (5) Front service brake (6) Rear Service Brake (7) Parking brake (8) Brake charge pilot gear pump (9) Hydraulic oil cooler (10) Cooler bypass valve (11) Piston accumulator (12) Brake charge valve (13) Brake charge pressure sensor (14) Parking brake valve | |
Service brakes "RELEASED" with parking brake "ENGAGED"
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| Illustration 2 | g06265719 |
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Service brakes "RELEASED" with parking brake "ENGAGED" (1) Hydraulic tank & filters (2) Foot brake control group (3) Service brake control valve (4) Parking brake actuator (5) Front service brake (6) Rear Service Brake (7) Parking brake (8) Brake charge pilot gear pump (9) Hydraulic oil cooler (10) Cooler bypass valve (11) Piston accumulator (12) Brake charge valve (13) Brake charge pressure sensor (14) Parking brake valve (15) Main Relief valve (16) Accumulator (17) Pilot valve (18) Pressure reducing valve | |
This schematic shows the 814K brake hydraulic system with the service brakes "RELEASED" and the parking brake "ENGAGED". The brake charge / pilot pump sends oil through the brake oil filter to brake charge valve (12). Inside brake charge valve (12), oil flows to main relief valve (15) and pilot pressure reducing valve (18). The relief valve limits the maximum pressure for the brake system. The pressure reducing valve decreases the brake oil pressure, which is used as the pilot oil supply for the implement and steering systems. Piston accumulators (11) are charged to maintain pressure while the engine is running. The accumulators will continue to charge until the oil pressure increases to
If the machine loses power or if the hydraulic pump fails, the service brakes can still be "ENGAGED". The accumulator pressure permits a minimum of nine applications to the service brakes to stop the machine or slow the machine enough to engage parking brake (7). When the right brake pedal is depressed, the stop lamp switch is closed, which illuminates the brake lights on the back of the machine. When the right brake pedal is depressed, the right brake pedal switch signals the Engine ECM to disable the throttle lock function. The Engine ECM sends the switch position data over the Cat Data Link to the Power Train ECM.
When the parking brake switch in the cab is in the ON position, the Power Train ECM de-energizes the parking brake solenoid in the parking brake control valve (14). Parking brake oil is directed to the tank, and spring force causes the parking brake actuator to engage parking brake.
Service Brakes "ENGAGED" with the parking brake "RELEASED"
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| Illustration 3 | g06265721 |
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Service Brakes "ENGAGED" with the parking brake "RELEASED" (1) Hydraulic tank & filters (2) Foot brake control group (3) Service brake control valve (4) Parking brake actuator (5) Front service brake (6) Rear Service Brake (7) Parking brake (8) Brake charge pilot gear pump (9) Hydraulic oil cooler (10) Cooler bypass valve (11) Piston accumulator (12) Brake charge valve (13) Brake charge pressure sensor (14) Parking brake valve (15) Accumulator (16) Pilot Valve | |
When the parking brake switch in the cab is in the"OFF" position, the Power Train ECM energizes the parking brake control valve solenoid in the parking brake control valve (14). The parking brake solenoid directs oil from piston accumulators (11) to the parking brake spool inside the parking brake control valve. Brake accumulator oil is directed to parking brake actuator (4), which releases parking brake (7).
When the right brake pedal or the left brake pedal is depressed, movement of the brake pedal is mechanically transmitted to the service brake control valve (3). The service brake valve moves down and directs brake system oil to engage front service brake (5) and rear service brake (6).