With a truck backed into position at the loading dock the overhead door is opened, the truck is then restrained using a vehicle restraint safety system or wheel chocks and the dock leveler is now ready to operate.

The dock leveler deck assembly raises and when fully raised the hinged lip extends, the deck and extended lip are lowered into position with the lip at rest on the bed of the truck. The truck is now ready to be loaded or unloaded.

The lift truck drives across the dock leveler deck and lip onto the bed of the truck. The weight of the lift truck forces the truck suspension down as it drives onto the truck bed and when the lift truck drives back off the trucks suspension pushes the truck bed back up. The dock leveler moves up and down and the lip maintains positive contact throughout this vertical range.

The up and down movement of the dock leveler as the lift truck drives in and out of trailer is referred to as dock leveler float.

Hydraulic and pneumatic dock levelers are referred to as downward biased, at rest they are either stored in the closed position or in the operating position with the lip on the bed of the truck.
Mechanical dock levelers are upward biased; the lift springs are continually pushing the deck assembly upward. Mechanical dock levelers are equipped with a hold down device that locks the dock leveler deck assembly in the closed stored position. When in use the hold down assembly locks the extended lip to the truck bed.

Dock leveler float has little impact on hydraulic or pneumatic dock levelers as the deck assemblies are free to float up and down in a neutral state as the truck suspension moves the truck bed up and down. Mechanical dock levelers are a different story.

The hold down assembly locks the dock leveler lip to the truck bed and any upward truck bed motion is compensated by an internal spring within the hold down device.

To minimize this additional force on the hold down device it is required that any truck/trailer that is equipped with an air ride suspension that the air is released prior to the dock leveler being cycled. Releasing the air from the suspension minimizes the amount of dock leveler float and reduces the negative effects on the hold down assembly.

For additional information on any Pentalift product please contact the Pentalift Sales Department.