Abstract: Apparatus which enables a foldable wheelchair to be retrofitted with an electrical propulsion system without significantly compromising the ability to fold the chair. The apparatus includes a drive unit for each wheel to be driven. The drive units can be mounted on the stationary axles of the driven wheels and apply torque, generated by a separate motor in each drive unit, to the wheels at a plurality of symmetrically located points which are radially displaced from the axles.

Abstract: Apparatus for generating coded signals commensurate with information to be entered into associated equipment includes a matrix of magnetically operated switches. The switches are disposed beneath a generally planar data entry area and transparent indicia bearing overlays are received on the data entry area; the overlays including target points aligned with individual switches and there typically being fewer target points than switches whereby the overlay has space for the indicia and a plurality of overlays are utilized to take full advantage of the capability of the matrix. The apparatus may also include light emitting devices associated with the switches to provide operator feedback or guidance.