Belt linear translating motion

Input: pink crank. Grey pulley is stationary. Belt drive of transmission ratio 1/1 keeps yellow rotary runway always vertical. Triangular cam makes blue slider move up/down. Spring follower moves one way direction thanks to deep portion (in black) of the cam groove. So the blue slider translates along a triangular trajectory (green triangle). Time for tracing horizontal portion of the trajectory corresponds 1/2 input revolution. It can be used for plantigrade machines of 2 legs.