Patent ID: 6935448

Claim:
A suspension system for a vehicle comprising: a frame; at least one rear caster coupled to the frame; first and second pivoting assemblies, each pivoting assembly comprising at least one pivot arm having: a first portion pivotally coupled to the frame; at least one front caster coupled to a second portion of the pivot arm and normally in contact with a supporting surface of the vehicle; a drive system coupled to a third portion of the pivot arm; a base member having a top, bottom, and sides; an extension member projecting from the base member and terminating into the second portion coupled to the at least one front caster; a tubular sleeve disposed generally transverse to the base member and proximate the top of the base member and rear of the second portion, the sleeve configured for pivotally coupling the pivot arm to the frame; a planar mounting plate coupled to the bottom of the base member and having a plurality of apertures for mounting a drive system to the pivot arm, the mounting plate projecting laterally outward beyond the sides of the base member; wherein the first portion is coupled proximate to the frame so as to cause a first fraction of the weight supported by the vehicle to be supported by the drive system and the remaining fraction of the weight supported by the vehicle to be supported at least by the at least one front caster and urging the at least one front caster into contact with the supporting surface; and wherein the pivot arm farther comprises a pivoting behavior responsive to a force generated by the drive system, the pivoting behavior urging the at least one front caster from the supporting surface of the vehicle and at least partially shifting the fraction of weight being supported by the at least one front caster so that the weight supported by the vehicle is supported by the drive system and the at least one rear caster.