PORTABLE AND COLLAPSIBLE DERRICK STRUCTURE

摘要

PORTABLE AND COLLAPSIBLE DERRICK STRUCTURE A pickup truck derrick assembly includes a base frame, a derrick A-frame pivotally mounted on the base frame, a derrick frame erection subassembly, a frame support and locking subassembly and a cable compensation system. In one form, the frame erection subassembly includes an elongated track. A roller or carriage subassembly rides on the track and engages the A-frame. Movement of the carriage along the track raises and lowers the A-frame. The A-frame is held in an erected position by support braces pivotally connected at one end to the base frame. Each brace slidably engages a sleeve mounted on the A-frame. A locking mechanism automatically secures the braces to the sleeves when the A-frame is erected. In another form, the erection subassembly includes lead screw actuators combined with the support braces to raise and lower the A-frame and lock the frame in position. A pulley and cable arrangement including a compensation pulley on a support arm fixed to the A-frame compensates for hoist cable slackening when the A-frame is pivoted to its storage position.