Hydraulic Circuit Diagram: Dc-Powered Units; Operation Instructions For Dc-Powered Units (Dcr-880-H-Dc & Dcr-800-H-Hp-Dc) - Vestil DCR-880 Series Instruction Manual

rev. 6/7/2018
Pressure relief system
If a load that exceeds the maximum rated load is placed on the deck, or a mechanical malfunction interferes with
the movement of the deck, the pressure relief valve will open during a power-stroke. The pressure relief valve reduces
the likelihood that excessive loads will damage the lifter frame or the hydraulic system. The pressure relief valve
shunts oil directly from chamber A to the reservoir.
Release valve assembly
The foot-actuated release valve assembly is the mechanism that allows the deck to lower. When the release pedal
is pressed down, the release valve opens, and oil flows from the cylinder to the reservoir. The lowering rate is
adjustable; instructions appear under "Release pedal adjustment" on p. 22. Lowering rate is also variable: the farther
down the release pedal is pressed, the more rapidly the deck descends. The weight of a load on the deck affects the
flow rate, and therefore, a heavier load will lower more rapidly than a lighter load, regardless of the lowering rate
selected. When the operator lets the pedal loose, the release pedal tensioning spring returns the release pedal to the
home position, which automatically closes the valve.
Hydraulic circuit diagram (DC-powered units; 01-127-010 Rev. C):
Operation Instructions for DC-Powered Units (DCR-880-H-DC; DCR-880-H-HP-DC):
The drum carriage of electrically powered units is controlled by a handheld controller as well as pushbuttons on the
power unit housing. To raise or lower the carriage, press the appropriately marked button. When either button is
released, the carriage will maintain position.
To raise the carriage, press the UP button on the pushbutton controller. This starts the electric motor which turns
the hydraulic pump. Oil from the reservoir (inside the modular power unit) flows through a suction filter and into the
pump. The pump delivers pressurized oil to the hydraulic cylinder through a check valve. The check valve allows oil to
flow only in one direction, i.e. to the cylinders, and prevents oil from flowing back into the pump circuit when the pump
stops. This traps oil in the cylinder causing the carriage to maintain elevation after the control button is released.
If a load exceeds the capacity of the lifter, pressure will build up in the circuit between the pump and the cylinders
when the UP button is pressed. This pressure forces the relief valve to unseat which in turn allows oil to circulate back
Copyright 2018 Vestil Manufacturing Corp.
DCR-880, MANUAL
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