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| Illustration 1 | g01012948 |
Location of toggle switch, lever and ball valves (A) Toggle switch (B) OPEN position (C) CLOSED position | |
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| Illustration 2 | g01013016 |
Simplified hydraulic schematic (1) Line (2) Ball valve (3) Relief valve (4) Relief valve (5) Control valve (6) Line (7) Line (8) Line (9) Supply line (10) Pilot supply line (11) Pilot drain line (12) Counterweight lifting cylinder (13) Line (14) Line (15) Line (16) Line (17) Drain line to hydraulic tank (18) Spool valve (19) Solenoid valve (20) Line (21) Line (return) (22) Lever (23) Check valve (24) Line | |
Enabling the Removal Device for the Counterweight
The hydraulic activation control lever must be in the LOCKED position in order to activate the counterweight removal circuit. Ball valves (2) must be in the OPEN position (B). The counterweight removal circuit is enabled by toggle switch (A). Toggle switch (A) energizes solenoid valve (19). Solenoid valve (19) opens and pilot oil from line (10) flows through solenoid valve (19) to line (20). Pilot oil in line (20) shifts valve (18). Pump oil flows from line (9) through spool valve (18) and through line (7) to control valve (5) .
Pilot oil also flows through line (24) to the Stick II control valve and a resolver valve in the NFC line to the upper pump regulator. Pilot oil pressure from solenoid valve (19) and the NFC signal are sent to the resolver valve. The highest pressure is sent to the pump regulator in order to destroke the pump. This ensures that the pump flow to the counterweight cylinder is at a minimum flow.
Counterweight Lower Operation
When lever (22) is pulled down, control valve (5) shifts downward. Pump oil flows from line (7) through control valve (5) through line (16) and line (1) to the rod end of lift cylinder (12). Oil drains from the head end of the lift cylinder into line (14). Oil flows through relief valve (3), ball valve (2) and through line (15) to control valve (5). The oil flows through control valve (5), through line (6) , line (17), and line (21) to the hydraulic tank. The counterweight is lowered.
Counterweight Raise Operation
When lever (22) is pulled up, control valve (5) shifts upward. Pump oil flows from line (7) through line (15) and through ball valve (2) to relief valve (3). Pump oil flows through check valve (23) and through line (14) to the head end of lift cylinder (12). Oil drains from the rod end of lift cylinder (12) through line (1) and through line (16) to control valve (5). The oil flows through control valve (5), line (6), line (17), and line (21) to the hydraulic tank. The counterweight is raised. When lever (22) is placed in the NEUTRAL position, check valve (23) prevents the oil in the head end of lift cylinder (12) from flowing out of the lift cylinder.
Relief Operation of the Cylinder Head End
When counterweight lift cylinder (12) is pushed downward by an outside force the oil pressure in the head end of the lift cylinder increases. The oil pressure is sensed at relief valve (3). When the relief valve opens the oil flows back to the hydraulic tank.