Patent ID: 7506405

Claim:
A pair of carriages operable to cooperatively support a rigid load for movement across a surface, wherein the carriages are spaced apart and the load extends therebetween in a spaced direction, each of said carriages comprising: at least two caster assemblies, each of which includes a base section and at least three rotatable caster wheels attached to the base section so that the caster assembly is self-supporting; a load-supporting section operable to support the load thereon; a linkage interconnecting the caster assemblies; and at least two pivot couplers, each being pivotally attached to a respective one of the base sections and the linkage to define a pair of base pivot axes associated with the respective caster assembly, each of said pivot couplers cooperating with the respective base section and the linkage to restrict relative movement between the respective caster assembly and linkage to pivoting movement about the base pivot axes, said linkage being pivotally connected to the load-supporting section about an intermediate pivot axis, said load-supporting sections of the carriages having a positional relationship which is maintained substantially constant as the carriages move across the surface.