PROBLEM TO BE SOLVED: To provide a lock mechanism capable of freely locking/releasing a caster, when a wheelchair travels.SOLUTION: A lock mechanism of a caster includes a first plate-like member fixed so that its plane becomes vertical to a rotary shaft of a caster, a second plate-like member movably fixed in the axial direction of the rotary shaft while its plane is maintaining parallel to the plane of the first plate-like member and lock state switching means for switching a lock state and a lock release state of the caster, and is provided so that in the second plate-like member, N pieces of rod-like projection parts having the respectively different lengths are formed on a concentric circle with the axis of the rotary shaft as the center, and in the first plate-like member, a circular opening part capable of fitting the shortest projection part when the caster turns in the straight advance direction is formed, and (N-1) pieces of circular arc-shaped opening parts capable of slidably fitting its excess (N-1) pieces of projection parts are formed on the concentric circle.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2017,JPO&INPIT【課題】車椅子の走行中に、キャスタのロック/解除を自在に行うことができるロック機構を提供する。【解決手段】その平面がキャスターの回転軸に対して垂直になるように固定される第1の平板状部材と、その平面が該第1の平板状部材の平面との平行を維持したまま該回転軸の軸方向に移動可能に固定される第2の平板状部材と、前記キャスターのロック状態とロック解除状態を切り換えるロック状態切替手段とを含み、前記第2の平板状部材には、それぞれが異なる長さを有するN個の棒状の突起部が前記回転軸の軸心を中心とする同心円上に形成され、前記第1の平板状部材には、前記キャスターが直進方向に向いたときに最短の前記突起部が嵌合可能な円形開口部が形成されるとともに、その余の(N-1)個の前記突起部が摺動自在に嵌合可能な(N-1)個の円弧状開口部が前記同心円上に形成される、キャスターのロック機構が提供される。【選択図】図1
