Abstract: An apparatus for obtaining substantially equal step length of each jack in a group of pressure fluid operated climbing jacks working on a common object for lifting or lowering it. The apparatus comprises at least one compensation jack associated with each climbing jack. The compensation jacks are arranged to transfer substantially the same load as the respective associated climbing jack and to be actuated when the climbing jack has carried out a full stroke without reaching the intended step length, in order thereby to effect a complementary movement of the load.