PUMP GP-FUEL INJECTION 3979945 - Caterpillar

Illustration 1 g01005548
Schematic of Bowl In LOWER Position (1) Vent valve (2) Vent line from carry-check valves (3) Scraper control valve (4) Valve stem for ejector cylinder and floor cylinder (5) Valve stem for bowl cylinders (6) Return line to oil filter and hydraulic tank (7) Carry-check valve (8) Pressure equalizer line (9) Main relief valve (10) Oil filter (11) Bowl cylinders (12) Line to rod end of bowl cylinders (13) Hydraulic pump (part of hydraulic and steering pump) (14) Line to head end of bowl cylinders (15) Floor cylinder (16) Ejector cylinder (17) Steering pump (part of hydraulic and steering pump) (18) Hydraulic tank (19) Floor check valve (A) LOWER position (B) HOLD position (C) RAISE position (AA) Pressure oil (HH) Trapped oil (LL) Drain oilNote: The bowl cylinders are mounted on the machine with the rod end downward.Bowl HOLD
When bowl valve stem (5) is in the HOLD position, the flow of oil in lines (2), (12) and (14) are blocked. In this HOLD position, vent valves (1) will not open because the oil in the spring passages of line (2) is blocked. This blocks the oil in the spring passages of carry-check valves (7). The HOLD position will also hold carry-check valves (7) closed. Carry-check valves (7) hold bowl cylinders (11) in position. Carry-check valves (7) will not allow bowl cylinders (11) to move until bowl valve stem (5) is moved again.Bowl LOWER
Illustration 2 g00621052
(20) Bowl Control LeverWhen the bowl valve stem (5) is moved to the LOWER position (A), the oil in the vent line (2) is drained to the hydraulic tank (18) through the bowl valve stem (5). Because there is no oil pressure in the spring passages of the vent valves (1), the vent valves will open. This will allow the carry-check valves (7) to open also.When bowl valve stem (5) is moved to the LOWER position (A), oil from the hydraulic pump (13) flows around the bowl valve stem (5). The oil then flows through line (14) to the head ends of the bowl cylinders (11). The pump oil in the head end of the bowl cylinders (11) moves the piston rods that are connected to the bowl downward. The piston rods are held there until the bowl control lever (20) is released. The piston rods will be released if the piston rods can not travel farther into the bowl cylinders (11). When the bowl stops lowering and the bowl control lever (20) is not released, the pressure of the pump oil will increase. If the pressure of the pump oil reaches the pressure setting of main relief valve (9), the main relief valve will open. The oil pressure will no longer increase.As the piston rods move downward, oil is pushed out of the rod ends of bowl cylinders (11) through carry-check valves (7). Because bowl valve stem (5) is in the LOWER position, the rod end oil will flow through carry-check valves (7) and open vent line (2). Vent valves (1) can not