Abstract: A pinch clamp finding a primary use in an autotransfusion machine includes a hollow clamp head having a closed upper end and an open lower end reciprocally receiving a piston. A lateral groove is established in the clamp head so that a deformable tube can be received in the clamp head passing through the hollow interior thereof. The piston is reciprocally moved within the clamp head so as to selectively pinch the tube between the piston head and the closed end of the clamp head. The piston is positively reciprocated by cam followers on a piston rod with the cam followers riding in closed cam tracks in adjacent cam wheels on opposite sides of the piston. The cam wheels are mounted on a crankshaft which is selectively driven by power means.