SELF-ACTUATING SLACK PULLER

摘要

A slack puller has symmetrical sheave assemblies on each side of a cable path. The sheave assemblies each include a driven sheave mounted on an arm. When the sheaves are engaged with the cable by an actuator, tension in the cable pulls the sheaves in a way which tends to increase the compressional forces exerted by the sheaves on the cable. The self actuating nature of the slack puller allows compressional forces on the cable to be kept small until the cable comes under tension. The sheaves are driven by positive displacement hydraulic motors connected in series with a hydraulic pump. This permits the sheaves to turn quickly when the cable is not under tension and slows the sheaves as tension in the cable increases. The slack puller operates more quickly and causes less cable damage than conventional slack pullers. The slack puller has particular application in skyline logging operations where its compact size is an additional advantage.