Abstract: A manual propulsion mechanism for wheelchairs utilizes a lever pivotally mounted to the hub of each rear wheel such that the wheelchair user can propel the chair with push/pull movements of the levers. Forward and reverse propulsion directions are accomplished by a system of one-way reversible clutches contained in the propulsion wheel hubs which also allow the levers to be operationally disconnected such that the chair can freewheel. Operator control of direction shifting is through pivoting motions imparted to the grip handles of the propulsion levers. In a preferred embodiment, improved ergonomics for propulsion direction changes are made possible by coordinating the direction of the shift pivot motion with the push/pull movement of the levers. This allows the operator to retain a comfortable, stable grip on the grip handle while simultaneously propelling and controlling direction of movement.

Abstract: A manual propulsion mechanism for wheelchairs utilizes a lever pivotally mounted to the hub of each rear wheel such that the wheelchair user can propel the chair with push/pull movements of the levers. Forward and reverse propulsion directions are accomplished by a system of one-way reversible clutches contained in the propulsion wheel hubs which also allow the levers to be operationally disconnected such that the chair can freewheel. Operator control of direction shifting is through pivoting motions imparted to the grip handles of the propulsion levers. In a preferred embodiment, improved ergonomics for propulsion direction changes are made possible by coordinating the direction of the shift pivot motion with the push/pull movement of the levers. This allows the operator to retain a comfortable, stable grip on the grip handle while simultaneously propelling and controlling direction of movement.

Abstract: A manual propulsion mechanism for wheelchairs utilizes a lever pivotally mounted to the hub of each rear wheel such that the wheelchair user can propel the chair with push/pull movements of the levers. Forward and reverse propulsion directions are accomplished by a system of one-way reversible clutches contained in the propulsion wheel hubs which also allow the levers to be operationally disconnected such that the chair can freewheel. Operator control of direction shifting is through twisting motions imparted to the grip handles of the propulsion levers. In a preferred embodiment, improved ergonomics for propulsion direction changes are made possible by an improved short excursion clutch shifting mechanism that reduces the angle of arc through which the operator must twist the grip handle to effect the direction change. This allows the operator to retain a comfortable, stable grip on the grip handle while simultaneously propelling and controlling direction of movement.

Abstract: A machine tool comprises a base with an upstanding column, a vertical spindle axis tool driving unit symmetrically located and vertically movable on the front of the column, a frontwards oriented horizontal spindle axis tool driving unit symmetrically located and vertically movable extending through the column, and a pair of guiding rails to extend vertically thereon and horizontally spaced apart from each other for guiding the upward and downward movement of the tool driving units. Symmetrically disposed counterbalance weights for both tool driving units are located within the column. Independent leadscrew driving means provide vertical upward and downward movement of the tool driving units.