BUSHING-PIVOT 1077894 - Caterpillar

Illustration 1 g01041139
(1) Ride control accumulators (2) Ride control solenoid valve (3) Lift cylinders (4) Tilt cylinder (5) Lines to auxiliary cylinders (6) Valve to lower attachment or bucket with dead engine (7) Main relief valve (8) Bank valve (9) Line to the steering system (10) Gear pump (11) Pilot oil accumulator (12) Pilot valves (13) Hydraulic oil filters and tank (14) Hydraulic oil cooler (15) Pilot supply line from hydrostatic pump (16) Hydraulic lockout valve (17) Return line from the hydrostatic pump (18) Hydrostatic pump (19) Tilt pilot valve (20) Main control valve for tilt (21) Tilt control lever (22) Lines to hydrostatic systemNote: The pilot control system for tilt in the 914G and 914G2 operates in the same manner as the other pilot control systems on the machine. Only the tilt pilot control valve will be discussed in this pilot hydraulic system.Note: The pilot control system in the 914G and 914G2 operates in the same manner as the pilot control system in the IT14G and IT14G2. The pilot system uses low-pressure oil to operate the bank valve (8). The main components of the pilot system include the following components: hydrostatic pump (18), lockout valve (16) and pilot valves (12) .With a running engine, oil flows from hydraulic tank (13) to the hydrostatic pump (18). The oil continues to flow through accumulator (11). Before the oil reaches the pilot valve (12), the oil must flow through hydraulic lockout valve (16). Refer to Specifications, RENR6491, "Piston Pump (Hydrostatic)" for the pressure of the pilot system.Note: For more information on hydrostatic pump (18), refer to System Operations, RENR6491, "Piston Pump (Hydrostatic)".After the oil arrives at the hydraulic lockout valve (16), the oil flows into pilot valve (12). The tilt pilot valve (19) is a closed center valve that has the following three positions: TILT, HOLD and DUMP. In the HOLD position, oil cannot flow through tilt pilot valve (19), because tilt pilot valve (19) is a closed center valve.Oil lines connect the output of the tilt pilot valve (19) to the pilot inlets on the main control valve for tilt (20) .When the tilt control lever (21) is moved to the DUMP position, oil flows to the main control valve for tilt (20). This position causes the spool for the bank valve for tilt (20) to move. Movement of the spool in the main control valve (20) opens passages. The passages send pressure oil for the implement to the rod end of tilt cylinder (4) .The movement of the spool (20) also opens a passage for return oil from the head end of the tilt cylinder (4). This passage allows flow back to hydraulic tank (13). Pressure oil for the implement acts on the rod end of tilt cylinder (4). This pressure causes the head end of tilt cylinder (4) to be vented to tank. This sequence of events causes the bucket to dump.When the tilt control lever (21) is moved to the TILT position, oil flows to the