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| Illustration 1 | g00690739 |
Section View of Carry-Check Valve and Quick-Drop Valve (1) Vent line (2) Vent line (3) Passage for common oil line (4) Passage for head end of bowl cylinder (5) Quick-drop valve (6) Carry-check valve (7) Passage for pump oil from main control valve (8) Passage for rod end of bowl cylinder (9) Check valve | |
When the bowl valve stem is in the QUICK-DROP position, vent lines (1) and (2) are open to the tank. Pressure oil from the common oil line flows through passage (3). The pressure oil opens carry-check valve (6) and flows through passage (4) to the head end of the bowl cylinder. Oil from the rod end of the cylinder flows through passage (8) and opens check valve (9). The oil flows through check valve (9) in order to open quick-drop valve (5). This oil then flows through passage (4) into the head end of the bowl cylinder. With the additional oil flow from the rod end of the bowl cylinder, the bowl moves down at a faster speed than the speed of the bowl in the LOWER position.
When the bowl valve stem is in LOWER position, vent line (1) is closed and quick-drop valve (5) cannot be opened. Oil from the rod end of the bowl cylinder must flow through opening (7) to the main control valve and into the hydraulic tank.
When the bowl valve stem is in HOLD position, both vent lines (1) and (2) are closed. The rod tries to extend out of the bowl cylinder because of the weight of the bowl. The rod cannot extend because the oil that is under pressure in the rod end of the bowl cylinder cannot open check valve (9). An external force cannot raise the bowl because oil that is under pressure in the head end of the bowl cylinder cannot open carry-check valve (6) .
When the bowl valve stem is in RAISE position, pressure oil from the pump flows through the main control valve into passage (7). The pressure oil opens check valve (9) and flows through passage (8) to the rod end of the bowl cylinder in order to lift the bowl. The oil from the head end of the bowl cylinder flows through passage (4). The oil opens carry-check valve (6). This oil flows through passage (3) to the common oil line and back to the main control valve.
There is an orifice in each valve. The orifice allows oil out of the spring chamber when the valve is pushed open.