Method and apparatus for transporting and steering a load

A load-carrying transport apparatus for moving first and second loads over a surface, the transport apparatus comprising:

• a first substructure for supporting the first load above the surface;
• a first track member having an elongate, substantially planar upper face positioned on the surface adjacent the first substructure;
• a second substructure for supporting the second load above the surface;
• a second track member having an elongate, substantially planar upper face positioned on the surface adjacent the second substructure;
• first and second lift assemblies mounted on the first and second substructures, respectively, each having a roller assembly mounted on one end thereof, each roller assembly including a plurality of rollers, and each lift assembly being selectively operable for extension so that its roller mechanism engages the planar face of its adjacent track member and upon further extension to raise its respective substructure above the surface, each lift assembly also being selectively operable for retraction to lower its respective substructure to the surface and disengage from its adjacent track member;
• and
• first and second shifter mechanisms disposed adjacent the first and second substructures, respectively, each being selectively operable to displace its adjacent substructure by rolling it along its adjacent track member to substantially maintain the relative positioning of the substructures when the lifting assemblies have been extended to raise the substructures above the surface, the shifter mechanisms also being operable for displacing their respective track members in a selected direction on the surface when the lifting assemblies have been retracted from the track members to lower the substructures to the surface.

A method for transporting a load over a surface, the method comprising:

• supporting the load above the surface by a substructure;
• selectively extending a plurality of lift assemblies mounted on the substructure to raise the substructure above the surface;
• displacing the substructure along a track member positioned on the surface adjacent the substructure;
• retracting the lift assemblies to lower the substructure to the surface and disengage from the track member;
• and
• displacing the track member on the surface to move it substantially in the same direction as the substructure.

A steerable load-carrying apparatus for transporting a load over a surface, the apparatus comprising:

• a substructure for carrying the load above the surface;
• a track member providing a steering area, the track member positioned on the surface adjacent the substructure;
• a plurality of steerable lift assemblies interposed between the substructure and the track member, each lift assembly being selectively operable for extension to engage the track member and raise the substructure above the surface for support on the track member, at least one of the lift assemblies being selectively positionable to a predetermined angle within a range for moving in the steering area along the track member;
• and
• a shifter mechanism disposed adjacent the substructure and the track member selectively operable for displacing the substructure relative to the track member when the lifting assemblies support the substructure on the track member above the surface and for displacing the track member relative to the substructure when the lifting assemblies have been retracted and disengaged from the track member so that the substructure has been lowered onto the surface.