Foldable invalid chair

Claim 1

A foldable wheel chair comprising two side frames, a seat supported by said side frames, scissor-action links hingedly connecting said side frames, horizontal bearings mounted on each side frame, two driving wheels, the axle of each driving wheel being mounted in each horizontal bearing, vertical bearings mounted on each side frame, a laterally pivotable bearing means mounted in each of said vertical bearings, two dirigible wheels, the axles of said dirigible wheels being mounted in said bearing means, first coupling means provided on the axles of said driving wheels and facing the axis of symmetry of said wheel chair, a propulsion drive detachably mounted between said side frames, said propulsion drive having an electric motor in a removable unit as prime mover, second coupling means drivingly connected to said propulsion drive, axial coupling members engaging in said first and second coupling means such that said first and second coupling means are drivingly connected, positioning means provided on one of said side frames to prevent said propulsion drive from rotating with respect to said side frames, a driving shaft detachably engaging one of said first coupling means on one side of the propulsion drive, at least one of said axial coupling members being spring loaded against one of said first coupling means and displaceable in the direction of the propulsion drive, each of said first coupling means being rigidly connected to an axle of said driving wheels and formed from resilient material capable of withstanding torsion forces, each of said second coupling means being formed of a rib which is secured to the axial coupling member, and extends at a right angle to the longitudinal axis of the driving shaft, two oppositely disposed guide sleeves being provided on each side of said driving shaft, a pin with a knob being held in the engaged position in said sleeves by a compression spring, the pin being lockable in the uncoupled position, at least one slit being provided in each sleeve, a clamping pin engaging in said at least one slit, said clamping pin serving as an abutment for the compression spring, each of said first coupling means being formed by a disc having two insertion apertures for said pins, a supporting rib being rigidly secured to each driving wheel axle, each of said first coupling means being detachably secured to said supporting rib.