STUD 6I0840 - Caterpillar

Illustration 1 g01421436
Right side view of the pilot hydraulic system (1) Hydraulic lockout system (2) Tilt control lever (3) Lift control lever (4) Pilot valve (5) Return line to hydraulic oil tank (6) Pilot line (RAISE) (7) Pilot line (DUMP) (8) Pilot line (LOWER) (9) Pilot line (TILT BACK)The following items are located to the right of the operator's seat: Hydraulic lockout switch (1), tilt control lever (2), lift control lever (3) and pilot valve (4). Tilt control lever (2) and lift control lever (3) are attached to pilot valve (4) .Pilot oil is supplied to the pilot valve through a pressure reducing valve. the pressure reducing valve is located in the main implement valve. Pilot supply oil flows to the pilot shutoff valve and pilot supply oil is stored in the pilot accumulator. This valve reduces the inlet pressure for the main implement valve. Then, the pilot oil flows through the hydraulic lockout valve and into the supply line to pilot control valve (4). On a standard machine, the pilot valve is equipped with two separate valves. One valve is for the lift function and the other valve is for the tilt function. Also, the pilot valve may be equipped with a third valve for an auxiliary function or the pilot valve may be equipped with a fourth valve for an auxiliary function.When the operator moves lift control lever (3) to the RAISE position, pilot oil flows through pilot pressure oil line (6) to an end cap in the main control valve. The flow of pilot oil in the end cap places oil pressure against the valve spool. The movement of the valve spool allows pump supply oil from the implement pump to flow to the lift cylinders.Pilot oil from the opposite end of the valve spool flows through oil line (8) and back to the hydraulic tank through return line (5) .Note: The flow of oil through pilot pressure oil line (6) and (8) reverses when lift control lever (3) is moved to the LOWER position.When the operator moves tilt control lever (2) to the TILT BACK position, pilot pressure oil flows through pilot pressure oil line (9) to an end cap in the main control valve. The flow of pilot oil in the end cap places oil pressure against the valve spool. The movement of the valve spool allows pump supply oil from the implement pump to flow to the tilt cylinder.Pilot oil from the opposite end of the valve spool flows through pilot line (7) and back to the hydraulic tank through return line (5) .Note: The flow of oil through hydraulic oil lines (9) and (7) reverses when tilt control lever (2) is moved to the DUMP position.The pilot hydraulic control system is equipped with a rocker switch. The rocker switch is used in order to disable the implement system. When the rocker switch is in the LOCKED position, the flow of pilot oil to pilot valve (4) is blocked. The control