| 摘要 |
A vehicle including a load frame, a drive assembly, and a pivot link assembly. The load frame includes castor wheels to rollingly support the load frame on a support surface. The drive assembly includes a drive frame, a drive wheel, and a rigid castor wheel wherein the drive wheel and rigid castor wheel are each mounted to the drive frame. The pivot link assembly couples the drive frame to the load frame and permits the drive frame to move vertically and angularly relative to the load frame.
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