Patent ID: 6126379
Filing Date: 2000-10-03
Classification: B60P

Abstract:
A lift apparatus comprising:two substantially parallel, spaced-apart track members having first and second ends;a support structure for elevating the track members, the support structure including first posts for supporting the first ends of the track members and second posts for supporting the second ends of the track members;a winch for raising and lowering a cable;an extendable boom having a distal end over which the cable of the winch is draped, the extendable boom being telescopically mounted within a boom receiving portion, the boom receiving portion having a bottom side positioned opposite from a top side, the bottom side defining a longitudinal slot for receiving the cable of the boom when the boom is moved to a retracted position within the boom receiving portion, the boom receiving portion extending transversely between the two track members;roller assemblies corresponding to each of the track members for securing the boom receiving portion to the track members such that the boom receiving portion can slide along the lengths of the track members, the roller assemblies being mounted above the top side of the boom receiving portion with each including two upper rollers that ride above the track members;a drive shaft that extends between the track members, the drive shaft having end portions received within bearings located near the first ends of the track members;first gears mounted on the drive shaft and second gears positioned near the second ends of the track members;drive chains that extend along each of the track members, the drive chains being looped about the first and second gears and including vertically spaced-apart upper and lower portions that extend between the first and second gears, the lower portions of the chains being secured to the boom receiving portion such that the boom receiving portion moves in concert with the lower portions of the chains;chain guides for stabilizing the upper portions of the chains, the chain guides being positioned along a reference line that extends generally between the upper rollers of the roller assemblies, the chain guides being supported by guide mounts that extend upward from the top side of the boom receiving portion, and the chain guides being adapted to ride over the upper portions of the chains; anda drive motor for rotating the drive shaft, wherein the rotation of the drive shaft causes the chains to move the boom receiving portion along the lengths of the track members.