Section 8.Theory of Operation

Model 5200 High-Level Orderpicker

Pump Sense

The pump sense line monitors the status of the pump contactor at all times. If the pump contactor is closed when commanded open, an error code displays and the PC contactor opens. If the pump contactor is open when commanded closed, an error code displays.

CV-1 Valve

This 5 psi (34.5 kPa) check valve makes sure that oil returning from the lift cylinders does not drive the lift pump and motor backward.

CV-2 Valve

This is the 100 psi (689.4 kPa) fork hang-up valve. If the pressure between the proportional valve and CV-2 falls below 100 psi (689.4 kPa), the valve closes and does not allow the carriage to lower.

Flow Control Valves

Each lift cylinder has a flow control valve at the bottom of the cylinder. If a lift hose fails, the flow in the side cylinders is limited to 9 gpm (34lpm) while the flow in the center cylinder is limited to 11 gpm (41.6 lpm).

Oil Filter Check Valve

The oil filter is mounte d to an adapter that incorporates a spring-loaded check valve. It provides a bypass around the filter in case the oil pressure in the return line is greater than what the filter can handle. Additionally, if the filter gets clogged, the oil bypasses the filter and return to the hydraulic reservoir.

REL-1

REL-1 is the high pressure relief valve. It opens when lift pressure exceeds the pressure necessary to lift a full-rated load.

Lift/Lower 8-12

Publication Number: 1043922B, Revised: 2 Sept 2015