Rig walking system with cantilever-mounted lifting jack assemblies

Abstract

A walking system for moving a load over the ground includes a substructure having laterally spaced-apart, rigidly interconnected main beams for carrying the load above the ground. A jack support beam is mounted as a cantilever on top of each main beam on opposite ends thereof, and each includes a lifting jack assembly. Each lifting jack assembly includes a power-driven hydraulic cylinder having a ram with a foot plate, and each is selectively operable for extending a ram downwardly to force the foot plate against the ground to raise the substructure off the ground, and for retraction to disengage the foot plates from the ground, thereby lowering the substructure to the ground. Each jack lifting assembly further includes a shifter mechanism selectively operable for displacing the main beams and the substructure along the ground in a selected steering mode when the lifting jack assemblies have been actuated to raise the main beams and the substructure above the ground.

We claim: 
     
         1 . A walking machine for moving a load over the ground comprising:
 a substructure having first and second main interconnected main beams for carrying the load above the ground;   a first lifting assembly mounted adjacent a first end of each main beam including a power-driven cylinder connected to a plunger element with a foot plate,   a second lifting assembly mounted adjacent an opposite, second end of each main beam including a power-driven cylinder connected to a plunger element with a foot plate,   wherein each power-driven cylinder is selectively operable for extending its plunger element downwardly to force its foot plate against the ground to raise the substructure off the ground, and for retraction to disengage its foot plate from the ground, thereby lowering the substructure to the ground;   a first shifter mechanism mounted on each first lifting assembly;   a second shifter mechanism mounted on each second lifting assembly;   each first shifter mechanism being selectively operable for simultaneous extension and retraction in opposition to one another to displace the main beam and the substructure along the foot plates in a selected steering mode when the lifting assemblies have been actuated to raise the main beams and the substructure above the ground.   
     
     
         2 . The walking system of  claim 1  wherein each support beam includes an extended end projecting outwardly from the end of its associated main beam, the extended end arranged for supporting a lifting jack assembly so that an associated foot plate is spaced outwardly from the end of its associated main beam. 
     
     
         3 . The walking system of  claim 2  wherein each support beam is mounted as a cantilever beam on its associated main beam so that the extended end is inclined relative to the long axis of the support beam mounted on the main beam. 
     
     
         4 . The walking system of  claim 3  wherein the support beam and its extended end are formed as a unitary box beam mounted to its associated main beam by detachable pin connections, wherein the extended section is provided with an internal, transversely-extending mounting plate for connection to an associated hydraulic cylinder; and
 wherein the extended end section includes an upper surface provided with an opening enabling access to the mounting plate and its associated hydraulic cylinder. 
 
     
     
         5 . A lifting mechanism for mounting on a main beam of a walking system substructure to facilitate selective raising and lowering of the substructure relative to the ground comprising:
 a support beam for mounting on top of a main beam adjacent an end thereof;   a lifting jack assembly for mounting on the support beam including a power-driven hydraulic cylinder having a ram with a foot plate, wherein the power-driven cylinder is selectively operable for extending and retracting the ram and foot plate; and   a shifter mechanism mounted on the lifting jack assembly selectively operable for displacing the foot plate relative to the support beam.   
     
     
         6 . The lifting mechanism  claim 5  wherein each support beam includes an extended end dimensioned to projecting outwardly from the end of a main beam to which it is to be mounted, the extended end arranged for supporting a lifting jack assembly so that an associated foot plate is spaced outwardly from the end of its associated main beam, when so mounted. 
     
     
         7 . The lifting mechanism of  claim 6  wherein each support beam is dimensioned to be mounted as a cantilever beam on a main beam so that the extended end is inclined relative to the long axis of the support beam when mounted on the main beam. 
     
     
         8 . The lifting mechanism of  claim 7  wherein the support beam and its extended end are formed as a unitary box beam for mounting on a main beam by detachable pin connections, wherein the extended section is provided with an internal, transversely-extending mounting plate for connection to the hydraulic cylinder; and
 wherein the extended end section includes an upper surface provided with an opening enabling access to the mounting plate and the hydraulic cylinder. 
 
     
     
         9 . A method for installing a lifting mechanism having a jack support beam and a lifting jack assembly onto the main beam of a walking system, wherein the walking system includes a substructure having laterally spaced-apart, rigidly interconnected main beams; comprising:
 lifting the jack support beam and placing it on top of a selected main beam of the walking system;   moving the jack support beam into a position adjacent mounting lugs on the main beam and determining if mounting lugs on the jack support beam are aligned therewith;   adjusting the position of mounting lugs on the jack support beam, if necessary;   welding the mounting lugs on the jack support beam into aligned position;   lifting the jack support beam into position above the jack lifting assembly and attaching them together as a unit;   lifting the jack support beam and attached lifting jack assembly as a unit into position on top of the main beam; and   aligning and connecting the lugs on the jack support beam with the lugs on the main beam.