The primary components of a standard configuration Pentalift dock lift power unit includes an electric motor, a gear pump, an oil reservoir, an electric solenoid operated lowering valve and an electrical control system.
Control buttons require constant pressure. To raise the lift the operator presses and holds the Up button on the controller. This activates the electric motor which is coupled directly to a gear pump. The rotating motor and gear pump draws hydraulic oil from the reservoir. The oil is pumped under pressure to the lift cylinder(s). As the lift cylinder(s) fill with hydraulic oil they extend the scissor legs and the platform rises.
On the output side of the gear pump the power unit is equipped with an internal check valve. When the dock lift has reached the desired height the operator releases the Up button, the gear pump check valve immediately closes. The closed check valve prevents the hydraulic oil from back flowing through the gear pump to the reservoir, the dock lift is held in the elevated position.
To lower the dock lift platform the operator presses and holds the Down button on the controller. This energizes the electric solenoid operated lowering valve to open. The hydraulic oil in the lift cylinder(s) flows back through the open lowering valve to the reservoir allowing the platform to lower. To stop the descent at any time the operator discontinues depressing the lower button.
To increase the lift speed of a dock lift a higher volume output pump is required. The larger pump increases the flow rate of hydraulic oil to the lift cylinder(s), the lift cylinder(s) extend quicker and this increases the platform lift speed. A higher horsepower rated electric motor is required to drive the higher volume output pump. The decision on what size power unit to apply to the lift should be made at the time of purchase.
The lowering speed of the dock lift cannot be increased. Pentalift selects and installs a suitably sized fixed flow control valve in the hydraulic return circuit. The fixed flow control valve regulates the amount of oil flow returning from the cylinder(s) through the valve back to the reservoir providing a safe controlled rate of descent.
Page 7 on the brochure link shows examples of Pentalift dock lift power units. https://www.pentalift.com/wp-content/uploads/2021/04/HED-Dock-Lift-Brochure.pdf
For additional information on any Pentalift product please contact the Pentalift Sales Department.