A hydraulic dock leveler overhead door interlock kit prevents the dock leveler from operating until the overhead door is open. Without an overhead door interlock kit there is the potential for significant accidental damage to the overhead door.
With the overhead closed and locked on top of a stored hydraulic dock leveler if a dock attendant accidentally activates the dock leveler control button there are sufficient upward forces generated that will cause significant damage to the closed overhead door.
How does the overhead door interlock kit work?
A standard hydraulic dock leveler has a control button or control panel to activate the dock leveler. When the dock attendant depresses the up button on the control panel this completes an electrical circuit from the incoming power supply to the lift motor and the dock leveler deck starts to rise with force from a hydraulic cylinder.
An overhead door interlock kit consists of a rocker arm activated limit switch c/w a mounting bracket that is installed on the inside wall 7-8 feet above finished floor level adjacent to the overhead door. The kit also includes a “striker” bar that is installed near the bottom of the overhead door.
The wiring from the dock leveler push button is routed to the wall mounted limit switch. With the overhead door closed the limit switch is wired “open” circuit. If the dock leveler up button is depressed nothing happens because the limit switch is open preventing an electrical supply to the dock leveler hydraulic power unit motor.
When the dock attendant opens the overhead door approximately 7’- 8’ the striker bar contacts the rocker arm limit switch and “closes” the circuit. The dock attendant now pushes the up button and the electrical circuit travels through the closed limit switch to the dock leveler hydraulic power unit motor and the deck raises.
After loading/unloading is completed and the dock leveler is returned to the closed stored position the overhead door is closed and the striker bar once again contacts the rocker arm limit switch and opens the circuit rendering the dock leveler inoperable.
For additional information on any Pentalift product please contact the Pentalift Sales Department.