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| Illustration 1 | g00933672 |
Schematic Of Hydraulic System (1) Bowl cylinders (3) Implement control valve (3A) Ejector valve spool (3B) Bowl valve spool (3C) Relief valve (3D) Ejector kickout solenoid (7) Oil line to head end of ejector cylinder and rod end of floor cylinder (7A) Pilot oil line (8) Oil line to rod end of ejector cylinder and head end of floor cylinder (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) EJECT position (B) HOLD position (C) RETURN 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
The HOLD position (B) of the ejector valve spool blocks the oil in lines (8) and (7). The ejector and the floor cannot move until the ejector control lever is moved.
Ejector Kickout Of The Ejector Valve Spool
When ejector valve spool (3A) is in the RETURN position (C), ejector kickout solenoid (3D) keeps the valve spool and control lever (29) in the RETURN position. When both cylinders are at the travel limit, there is an increase in the pump oil pressure at the pressure switch. When the pressure at the pressure switch becomes 15500 ± 350 kPa (2250 ± 50 psi), the pressure switch will open. An open pressure switch will de-energize the solenoid. This allows a spring to move the ejector valve spool to the HOLD position (B) .
Ejector Return
Pump (27) provides pressure oil to control valve (3) through line (19). When the ejector valve spool is in the RETURN position (C), oil flows through line (8) into the rod end of ejector cylinder (23). The oil also flows through floor check valve (22) into the head of floor cylinder (24) .
The area of the piston in the floor cylinder is more than the area of the piston in the ejector cylinder. This will move the floor cylinder first. The pump oil in the head end of the floor cylinder pushes the piston that is connected to the floor of the bowl. This closes the floor. Now, the oil in the rod ends of the ejector cylinder pushes the piston that is connected to the ejector. This causes the ejector cylinder to retract. When both cylinders reach the travel limit, ejector kickout (3D) will release the ejector valve spool.
Eject The Load
Hold the control lever in EJECT position. This keeps the ejector valve spools in EJECT position (A) in control valve (3). Pump pressure oil is directed through control valve (3), and through line (7). Pressure oil in line (7) is delivered to the head end of ejector cylinder (23) and to the rod end of floor cylinder (24). Floor cylinder (24) cannot retract because floor check valve (22) blocks the flow of oil from the head end of the cylinder. The oil in the head end of ejector cylinder (23) extends the rod. When the ejector cylinder reaches the travel limit, the pump oil pressure increases. Increased pressure in pilot line (7A) opens floor check valve (22). The open check valve allows the floor cylinder to retract.
The oil that is displaced by the cylinders flows through line (8). The oil flows through control valve (3) and through return oil line (14) into the filter and the tank.
When the ejector control lever is released, a spring on the ejector valve spool moves the valve spool to HOLD position (B). .