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| Illustration 1 | g00932684 |
Schematic Of Hydraulic System The system is shown with the bowl in the LOWER position. (1) Bowl cylinders (2) Carry-check valves (3) Implement control valve (3A) Ejector valve spool (3B) Bowl valve spool (3C) Relief valve (4) Oil line to head end of bowl cylinders (5) Vent line from carry-check valves (6) Oil line for rod end of bowl cylinders (9) Elevator control valve (14) Return oil line (15) Elevator motor (17) Diverter valve (19) Oil line to bowl and ejector control valve (22) Check valve (floor) (23) Ejector cylinder (24) Floor cylinder (25) Filter and tank (26) Vane pump (elevator) (27) Hydraulic and steering vane pump (AA) Pump pressure oil (BB) Tank Oil (CC) Blocked oil (A) LOWER position (B) HOLD position (C) RAISE position | |
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| Illustration 2 | g00933442 |
Scraper Control Levers (28) Bowl control lever (29) Ejector control lever (30) Elevator speed control lever | |
HOLD Position
When the control lever (28) is released, a spring on valve spool (3B) moves the control lever to the HOLD position (B). The oil passes through the open center of implement control valve (3) to the tank. All lines to the bowl cylinders are blocked.
Carry-Check Valves
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| Illustration 3 | g00933461 |
Schematic of carry-check valve (2) Carry-check valves (5) Vent line to implement control valve (6) Oil line to implement control valve (31) Balance line to the other carry-check valve (32) Line to the rod end of bowl cylinder (1) | |
Carry-check valve (2) contains a check valve and a bypass. When vent line (5) is blocked, oil is directed through the check valve. The check valve only allows oil to flow into the rod end of the bowl cylinder. When line (5) is blocked the bowl can only be raised. When line (5) is open, oil from the rod end of the cylinder fills both sides of check valve (2A). Orifice (2B) ensures that the pressure is higher on the side that is opposite of the spring. This higher pressure opens the check valve. This allows the bowl to be lowered. The carry-check valve ensures that the bowl will not be lowered if line (6) fails.
Lowering The Bowl
When bowl valve spool (3B) in control valve (3) is held in LOWER position (A), the oil from pump (27) goes to control valve (3) through line (19). The oil then goes out of the control valve through line (4) and into the head ends of bowl cylinders (1). The oil in the heads of cylinders (1) extends the rods. This lowers the bowl. The LOWER position of the valve spool opens line (6) to the tank and opens vent line (5) to the tank. The oil in bowl cylinders (1) that is pushed through carry-check valves (2) goes through line (6) and through line (5). The oil then flows through control valve (3) and return oil line (14) into tank (25) .
When control lever (28) is released, spool (3B) returns to the HOLD position (B).
Relief valve (3C) prevents damage due to high pressure in the implement circuits. If oil pressure increases, the pressure opens the relief valve. When the relief valve is open, oil flows through the control valve into line (14). The oil then flows to the tank.
Raising the Bowl
When control lever (28) is held in the RAISE position, bowl valve spool (3B) will be in the RAISE position (C). This allows the pump oil to flow through line (6) to carry-check valves (2). Oil flows through the carry-check valves into the rod end of bowl cylinders (1). The oil in the rod end of the cylinder retracts the rods in order to lift the bowl. The pistons push the oil out of the heads of the bowl cylinders to control valve (3). The oil goes through the control valve and through return oil line (14) into tank (25) .
When control lever (28) is released spool (3B) returns to the HOLD position (B).