Abstract: A drive assembly can comprise a plurality of drive arms that are configured to receive a tangential drive force and convert the tangential drive force to a torque about a first axis. A driven rotatable element can be rotatable about a second axis that is parallel to the first axis. A coupling subassembly can couple the plurality of drive arms to the driven rotatable element so that the first axis is movable with respect to the second axis in first and second dimensions that are perpendicular to each other and the first and second axes. The coupling subassembly can be configured to bias the driven rotatable element toward a position in which the first axis is collinear with the second axis.

Abstract: A foldable parallel bar apparatus includes generally U-shaped first and second end frames and a set of handrails connected to and extending between the first and second end frames, wherein the handrails are foldable so as to move the first and second end frames closer to one another thereby compacting the apparatus. When multiple modules of the end frames are connected, they provide an uninterrupted path between the handrails. An alternative embodiment provides base platforms that are foldable relative to each other and handrails that are vertically and horizontally adjustable.

Abstract: A foldable parallel bar apparatus includes generally U-shaped first and second end frames and a set of handrails connected to and extending between the first and second end frames, wherein the handrails are foldable so as to move the first and second end frames closer to one another thereby compacting the apparatus. When multiple modules of the end frames are connected, they provide an uninterrupted path between the handrails. An alternative embodiment provides base platforms that are foldable relative to each other and handrails that are vertically and horizontally adjustable.