A dynamical approach to piezoelectricity

A mechanism, useful in rough terrain for lifting and moving heavy loads short distances, resembles a tripod. The mechanism has three leg assemblies which are variable in length under control of an operator while subjected to axial loading. The legs are pivotally connected at their upper ends to a common crown block assembly and at each of their lower ends to a self-propelled base unit. A power source is associated with each leg assembly for varying the length of the associated leg assembly under axial loading. A winch is associated with one of the legs for reeling in and out a cable extending from the winch and via the crown block to a load. The mechanism is disassemblable for transport to a site of use. In its assembled state, the base units are disposed in spaced relation about a load and the legs are adjusted so that the crown block assembly is disposed over the load. After the load has been picked up, it is moved laterally within an area bounded by the base units by variation in the length of the variable-length leg assemblies.