FUSE 2I5185 - Caterpillar

Illustration 2 g01912498
Axle Housing (44) Brake disc pack (45) Differential (46) Brake cylindersThe braking system is composed of the following components:
Parking brake pressure switches (1) and (30)
Parking brake control valves (3) and (27)
Service brake control valves (5) and (25)
Brake accumulators (2) and (43)
Service brake pressure switches (7) and (23)
Load sensing valves (6) and (22)
Four brake disc packs (44)
Four brake cylinders (46)
Differential (45)
Differential locks (4) and (26) The implement pump supplies the hydraulic oil that is required to operate the braking system.Accumulator Charging System
The accumulator charging valve controls the amount of pressure oil that flows to brake accumulators (2) and (43). The accumulator charging valve contains an inverse shuttle section, a check valve, and an orifice.The orifice reduces the oil flow that enters the accumulator charging valve.The check valve prevents oil from flowing back through the accumulator charging valve to the implement pump.The inverse shuttle section of the accumulator charging valve will sense the pressure in the brake accumulators. When the oil pressure drops below 10500 kPa (1520 psi), the spool in the accumulator charging valve shifts so oil can flow to the brake accumulators. This oil pressure is the cut-in pressure.When the oil pressure reaches 20000 kPa (2900 psi), the spool in the accumulator charging valve shifts so oil flow is blocked to the brake accumulators. This oil pressure is the cutoff pressure.The brake accumulator charging valve contains a pressure switch. The pressure switch alerts the operator when inadequate pressure is available to charge brake accumulators (2) and (43). When the oil pressure drops below 8300 kPa (1200 psi), the pressure switch alerts the operator. "Brake Failure" will be displayed on the IQAN screen.Pressurized oil flows from the brake accumulator charging valve to the oil end of brake accumulators (2) and (43). Accumulators (2) and (43) contain a precharge of dry nitrogen. The precharge is approximately 6200 kPa (900 psi). The oil flows from accumulators (2) and (43) to brake control valve (5) and (25) .When the load sensing spool in the brake accumulator charging valve opens, a load signal flows through the brake valve. Then, the load signal flows from the brake valve to the implement pump. The signal upstrokes the pump in order to charge the brake accumulators.The implement pump is prevented from upstroking until the pilot switch is released. This action decreases the load on the engine. Thus, the engine is easier to start.When the operator releases the key, current is cut off in order to allow the load signal oil to flow to the implement pump from the brake accumulator charging valves.Working Brakes
Each brake application removes some of the oil from brake accumulators (2) and (43). The piston in each accumulator moves toward the oil end of the accumulator until there is a decrease in oil pressure. The brake accumulator charging valve permits oil from the hydraulic pump to flow to brake accumulators (2) and (43) until the pressure again rises.Brake control valve (5) or (25) controls front service brakes and the rear service