Portable overhead crane and method of installing it

Abstract

This disclosure relates to a method of and apparatus for lifting a load utilizing an existing bridge or gantry-type overhead crane in combination with a portable lifting beam or Strongback adapted to be lifted into position and partially supported by the existing bridge crane. The portable lifting beam includes a horizontally extending main beam having a telescoping section to reduce the longitudinal extent of the main beam to a dimension less than the distance between the parallel rails upon which the bridge crane is supported, whereby the lifting beam may be raised and lowered by the bridge crane between the parallel rails while being disposed perpendicular thereto. Once the lifting beam is lifted above the parallel rails, the hydraulic means are actuated to extend the telescoping section from its retracted position to increase the longitudinal extent of the main beam to a dimension equivalent to the distance between the parallel rails whereby the portable lifting beam or Strongback may be disposed thereon. The bridge crane and the Strongback are operable in tandem to lift a load, and include load cell means for correlating the operation of the respective lifting means to the bridge crane and Strongback whereby a load may be apportioned therebetween.