This creation is a kind of related wheelchair Anti-backup mechanism of what, and what mandrel is arranged wheel hub, the first Brake Block, the second Brake Block, unilateral bearing, sliding sleeve, spring and pushing block, and is pivotally connected trigger piece. First Brake Block is fixed on wheel hub. Unilateral bearing outer portion is fixed on the second Brake Block, the fixed sliding sleeve of internal ring portion. Sliding sleeve slidably but is un-rotatably covered in mandrel. When trigger piece is with respect to mandrel position one angle of what, wheel hub can bidirectional rotation with respect to mandrel. When another angle of the opposite mandrel position what of trigger piece, pushing block pushing tow sliding sleeve, cause the first Brake Block compressed spring and fixed with the second Brake Block closing, acted on by unilateral bearing and make wheel hub with respect to mandrel only single direction rotation, reaches with the purpose for preventing wheelchair rewind function.本創作係有關於一種輪椅防倒退機構，其於心軸套設輪轂、第一制動座、第二制動座、單向軸承、滑套、彈簧及推塊，並樞接扳柄。第一制動座固定在輪轂。單向軸承外環部固定在第二制動座，內環部固定滑套。滑套可滑動但不可轉動地套在心軸。當扳柄相對心軸位於一角度時，輪轂相對心軸可雙向旋轉。當扳柄相相對心軸位於另一角度時，推塊頂推滑套，致使第一制動座壓縮彈簧並與第二制動座靠合固定，藉單向軸承作用而使輪轂相對心軸只可單向旋轉，達到具有防止輪椅倒退功能之目的。
