Model 5200 High-Level Orderpicker
Section 8. Theory of Operation Lift/Lower
Lift/Lower
1. As the control handle lift knob is rotated, a voltage is applied to JPC13-6 on the Carriage Manager.
Lift The lift/lower potentiometer (VR2) commands the carriage to lift. When the lift knob is rotated, the lift/lower proportional solenoid valve (normally open) stays open while the lift contactor closes. After the contactor closes and the lift pump motor turns ON, the proportional solenoid valve ramps closes, forcing hydraulic fluid into the cylinders and increases lift speed. The proportional solenoid valve provides a smooth transition between zero speed lift and full speed lift and back to zero speed lift. When the lift knob is released, the proportional solenoid opens and the lift contactor opens turning OFF the lift pump motor. During lift, the load-holding solenoid valve remains closed (de-energized). The microprocessor on the Steer/Tractor Manager verifies the lift contactor remains closed when commanded closed, and open when commanded open. If either condition is not met, the Steer/Tractor Manager generates a fault code.
2. The Carriage Manager sends a lift command message to the Steer/Tractor Manager over the transmit/receive lines. 3. The Steer/Tractor Manager provides the negative potential for the lift pump contactor coil (JPT12-18) and the pump contactor coil is energized. The lift pump contactor LED (IL6-5) on the Steer/Tractor Manager indicates the pump contactor coil driver is energized. 4. When the lift pump contactor coil is energized, the lift pump contactor tips close supplying B+ to the lift pump motor. 5. The Steer/Tractor Manager provides the negative potential for the lift/lower proportional solenoid valve coil at JPT12-8, indicated by the solenoid control LED (IL6-7) on the Steer/Tractor Manager. The lift/lower proportional valve begins to ramp closed (this valve is normally open). 6. The lift pump/motor assembly is now running and supplying hydraulic pressure and flow to the lift cylinders.
LED IL6 IL1 +12V
IL6
Representing
IL6-1
Warning Light
IL6-2
Not Used
IL6-3
Hour Meter
IL6-4
Brake
IL6-5
Pump
IL4 +5V
IL6-6
Horn
IL6-7
Lift/Lower Solenoid
IL5 PC Disable
IL6-8
PC Contactor
IL6-9
Load-holding Solenoid
IL6-10
Deadman Switch 1 (S2)
IL2 (S23) Deadman 2 IL3 Heartbeat
Figure 8-2.
LEDs IL1-IL6 on Steer/Tractor Manager
Publication Number: 1043922B, Revised: 2 Sept 2015
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