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| Illustration 1 | g00933830 |
Schematic Of Hydraulic System The system is operating the elevator in the FAST FORWARD position. (1) Bowl cylinders (3) Implement control valve (9) Elevator control valve (9A) Passage (reverse) (9B) Passage (forward) (10) Oil line from steering control valve (11) Oil line to elevator motor (12) Oil line to elevator motor (13) Oil line to elevator control valve (14) Return oil line (15) Elevator motor (16) Drain line (17) Diverter valve (17A) Passage (17B) Passage (17C) Diverter valve spool (18) Return oil line from diverter valve (20) Vent line (21) Oil line to diverter valve (22) Floor check valve (23) Ejector cylinder (24) Floor cylinder (25) Filter and tank (26) Pump (elevator) (27) Hydraulic and steering pump (AA) Pump pressure oil (BB) Tank oil (CC) Blocked oil (DD) Pilot oil (A) REVERSE position (B) HOLD position (C) SLOW FORWARD position (D) FAST FORWARD position | |
Detent Operation Of Valve Spool For The Elevator Control Valve
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| Illustration 2 | g00933834 |
Valve Spool For The Elevator Control Valve The system is operating the elevator in the FAST FORWARD position. (9C) Spring (9D) Retainer (9E) Ball (four) (9F) Ring (9G) Spring (9H) Retainer (9J) Plunger (9K) Housing (9L) Chamber | |
The valve spool is manually operated. The ball detent in housing (9K) is used to hold the valve spool in either the FAST FORWARD, SLOW FORWARD or REVERSE positions. Springs (9C) will move the valve spool and the control lever to the HOLD position when the oil pressure in chamber (9L) decreases. This prevents the operation of the elevator when the machine is first started.
After the engine is started, the oil from the steering control valve flows into chamber (9L). This pushes plunger (9J) and retainer (9H) to the left. This puts spring (9G) in compression which pushes on ring (9F). Ring (9F) puts pressure against balls (9E) which are held in position by retainer (9D). Balls (9E) keep the valve spool in the HOLD position. When the valve spool is moved, balls (9E) will hold the spool in the desired position.
Fast Forward
When the valve spool is moved to the FAST FORWARD position (D), detent balls keep the valve spool in position. In this position, the valve spool opens forward passage (9B) of the elevator control valve. This allows oil in line (13) to flow through line (11). The valve spool also stops oil in vent line (20). Pressure from line (21) flows through diverter valve spool (17C). The pressure increases in the spring cavity. When the pressures are equal on both sides of the spool, the spring will shift the spool to the right. Pressure from line (21) is diverted through passage (17A). The oil from both sections of pump (26) are combined in line (11). Pressure oil now flows through line (11) to the elevator motor (15). This causes motor (15) to run at a faster rpm. The oil from the elevator motor goes through line (12), elevator control valve (9) and through return line (14) to tank (25) .
Slow Forward
When the valve spool is moved to the SLOW FORWARD position (C), detent balls keep the valve spool in position. In this position, the valve spool opens forward passage (9B) of the elevator control valve. This allows oil in line (13) to flow through line (11). Because vent line (20) is open, the spring cavity is constantly purging pressure. The pressure from line (21) will overcome the spring. Diverter valve spool (17C) shifts to the left. The oil in line (21) returns to the tank through line (18). Oil in line (11) goes to the elevator motor. Only oil from the large section of pump (26) flows through line (11). This causes the elevator motor to run at a slower rpm. The oil from the elevator motor flows through line (12) to elevator control valve (9). The oil then flows through return line (14) to tank (25) .
Reverse
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| Illustration 3 | g00933836 |
Scraper Control Levers (28) Bowl control lever (29) Ejector control lever (30) Elevator speed control lever (31) Lever (elevator direction control) | |
Speed control lever (30) cannot be moved to the REVERSE position until lever (31) is moved to the REVERSE position. Also, direction lever (31) cannot be moved to the REVERSE position unless elevator speed control lever (30) is in the HOLD position. When levers (30) and (31) are in the REVERSE position, the valve spool is in the REVERSE position (A). The detent balls will keep the valve spool in this position. In the REVERSE position, the valve spool opens reverse passage (9A) of the elevator control valve. This allows oil in line (13) to flow through line (12). The oil then flows to elevator motor (15). Because vent line (20) is open, the spring cavity is constantly purging pressure. The pressure from line (21) will overcome the spring. Diverter valve spool (17C) shifts to the left. The oil in line (21) returns to the tank through line (18). Only oil from the large section of pump (26) operates the elevator motor in the reverse direction. Oil from the elevator motor flows through line (11) to elevator control valve (9). The oil flows through return line (14) to tank (25) .