Gripper jacks use high tensile steel wedges with teeth to grip onto steel plates and bars, including the top flanges of skidding beams. They offer a precise, reliable and controllable method for horizontal movement of heavy structures, both onshore and offshore. As there is no requirement for pin holes or anchor points on the skid track and the gripping arrangement does not put large bending moments and shears into the steel plates/bars being gripped there is often a considerable cost saving in the manufacture of the skid track. . Gripper jacks are similar in principle to our other jacking systems, and can be used with our standard hydraulic power packs and control systems.
Our gripper jacks can be supplied with either a single anchor block or a pair of anchor blocks, and the anchor blocks can be either one-way gripping or two-way gripping. Single anchor gripper jacks are used to push and pull loads along a skid track where there is no risk that the load will runaway whilst the gripper jack is resetting for the next stroke and is not gripping the track. Two anchor gripper jacks are used when there is a need to hold the load securely in position during the reset stroke, or where the gripper jack needs to be able to self-walk along the skid track. One-way gripping anchors have a single pair of wedges which will hold the load in one direction only. Our gripper jacks are all designed so that a one-way anchor can be fitted to work in either direction. In this case to reverse the direction of skidding the user needs only to unbolt the anchor block, turn through 180 degrees and then re-bolt to the rams. Two-way anchors have two pairs of wedges pointing in opposite directions that are able to hold the anchor in position against both pushing and pulling forces.
DL-G50 gripper jack on an up stand plate, with 1 No two-way anchor.
2 No DL-G500 gripper jacks on a skid beam top flange for load out of offshore structures (1000 tonnes push / pull capacity). Each gripper jack has a single two-way gripping anchor block.
A specially made 500 tonne gripper jack with a pair of one-way gripping anchor blocks traveling along a square bar.