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| Illustration 1 | g00745053 |
Location of the Load Control Valve for the Telescoping Cylinder
Telescoping Cylinder (Boom Extend)
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| Illustration 2 | g00745054 |
Load Control Valve (Boom Extend) (1) Counterbalance valve (2) Screw (3) Locknut (4) Spring (5) Sleeve (6) Pilot passage (7) Annular face (8) Spring (9) Valve (10) Passage to bank valve (11) Holes (12) Valve seat (13) Passage to piston side of cylinder (14) Housing (15) Pilot passage (16) Pilot passage (17) Passage to rod side of cylinder (18) Passage to bank valve (19) Valve (20) Spring (21) Spring (22) Piston (23) Check valve (A) Implement Pressure (B) Return oil | |
Oil from the bank valve flows through passage (10). This causes valve (9) to move down against the force of spring (8) and oil flows through passage (13) into the piston side of the telescoping cylinder.
The pressure that is developed in the piston side of the telescoping cylinder is transmitted through pilot passage (15) and this oil pressure acts against the top face of piston (22). The piston moves down and contacts valve (19). Valve (19) moves down from the contact with piston (22) and this creates an opening between passages (17) and (18) .
As the telescoping cylinder extends, oil from the rod side flows through passage (17). The oil flows through open valve (19) and through passage (18) to the hydraulic tank via the bank valve.
Telescoping Cylinder (Boom Hold)
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| Illustration 3 | g00745055 |
Load Control Valve (Boom Hold) (1) Counterbalance valve (2) Screw (3) Locknut (4) Spring (5) Sleeve (6) Pilot passage (7) Annular face (8) Spring (9) Valve (10) Passage to bank valve (11) Holes (12) Valve seat (13) Passage to piston side of cylinder (14) Housing (15) Pilot passage (16) Pilot passage (17) Passage to rod side of cylinder (18) Passage to bank valve (19) Valve (20) Spring (21) Spring (22) Piston (23) Check valve (C) Blocked oil | |
Oil is blocked in the piston side of the telescoping cylinder by counterbalance valve (1) and in the rod side by check valve (23). Valve (9) in the counterbalance valve is seated by spring (8) and valve (19) in the check valve is seated by spring (20) .
The valve can be opened mechanically by loosening locknut (3), and turning screw (2) clockwise until the screw contacts valve (9). Screw (2) moves valve (9) away from valve seat (12). This allows oil in passage (13) to flow through passages (11) and (10). The oil flows back to the hydraulic tank via the bank valve.
Telescoping Cylinder (Boom Retract)
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| Illustration 4 | g00745056 |
Load Control Valve (Boom Retract) (1) Counterbalance valve (2) Screw (3) Locknut (4) Spring (5) Sleeve (6) Pilot passage (7) Annular face (8) Spring (9) Valve (10) Passage to bank valve (11) Holes (12) Valve seat (13) Passage to piston side of cylinder (14) Housing (15) Pilot passage (16) Pilot passage (17) Passage to rod side of cylinder (18) Passage to bank valve (19) Valve (20) Spring (21) Spring (22) Piston (23) Check valve (A) Implement Pressure (B) Return oil | |
Oil from the bank valve flows through passage (18) in the housing for the load control valve. The oil causes valve (19) to move down against the force of spring (20) and the oil flows through passage (17) to the rod side of the cylinder. The pressure that is developed in the rod side of the cylinder is transmitted through pilot passage (16) and the pressure acts on annular face (7) of valve sleeve (5) .
Sleeve (5) and valve (9) move up against the force of spring (4). When valve (9) contacts screw (2), the sleeve continues to move up creating an opening between passages (13) and (10). The oil now flows past valve seat (12) from the piston side of the cylinder through passage (10) and to the hydraulic tank via the bank valve.
To ensure positive control of the cylinder speed, the opening at valve seat (12) is proportional to the pressure that is applied to the rod side of the cylinder.