Most mechanical dock levelers use snubber mechanisms to lift the lips as they are raised, and they close slowly as shocks absorb the weight of the lip. In many of the Kelley dock levelers, however, a push bar and a yieldable rod are connected to a link assembly so that when the deck is raised the push bar drops down. Then, as someone walks across to the outside of the dock leveler, the plate on the push bar catches on the middle bolt allowing the push bar to raise the lip..
I'm not a professional, but I watched as my garage doors were serviced last year. The tech used a spray lubricant (I had bought a different brand in the garage door section of a home improvement store). He sprayed the inside of the entire track, top and bottom, the rollers that ride along the track, and all hinges on the door. He sprayed each hinge twice -- once on each side. The techs were more generous with the lubricant than I was when I'd done it before, so don't be afraid to give it a good squirt.