Most pull-chain dock levelers use main springs to counter the weight of the deck to lift the plate onto the bed of trailer. These springs have many configurations and over time are subject to fatigue.
The deck of a dock leveler is under pressure by its' main springs and is held down by a hold-down control.
Over time, a main spring (also known as a lifting spring) may crack and fatigue. A main spring will break shortly at this time. If your dock leveler has more than one spring, they often find themselves in similar condition near the same time.
The main spring(s) are typically attached to a tension bar threaded into a lifting arm (as seen above). The springs via the tension bar pull on the lifting arm, causing the deck to rise.
Main spring dimensions include overall length, outside diameter, number of coils, and wire size. To determine the overall length, measure from the inside of one end-hook to the inside of the other end-hook. The outside diameter is measured on the outside of the spring body. The wire size can be determined by use of a caliper or counting 10 coils, measuring its' length, and dividing the measurement by the coils (10).
Dock leveler manufactures have specific guidelines and recommended replacement parts for the equipment they engineer. Always refer to the Owner's Manual for equipment related operating requirements and safety guidelines.
