Abstract: A shape memory alloy step drive mechanism includes at least one shape memory alloy element (1) with a fixed end, the other end being connected to one end of a lever (2). The lever (2) is provided with a pawl (4) which is located to move on the teeth of a ratchet wheel (5) mounted on a main shaft (6) along with the lever (2). A stopper pin (7) is provided which also guides the pawl (4) on the ratchet wheel (5). A bias spring (9) is provided on a mandril on the main shaft (6) for returning the lever (2) to its original position. A detent wheel (8) with at least one detent lever (10) is mounted on the main shaft (6) to provide the detent torque required to hold the main shaft (6) in position when the lever (2) returns to its original position. A pair of support brackets (11) are provided for supporting and holding the various components together in an assembly.

Abstract: A shape memory alloy step drive mechanism comprising at least one shape memory alloy element (1) with a fixed end and the other end being connected to one end of a lever (2). The lever (2) is provided with a pawl (4) which is located to move on the teeth of a ratchet wheel (5) mounted on a main shaft (6) along with the lever (2). A stopper pin (7) is provided which also guides the pawl (4) on the ratchet wheel (5). A bias spring (9) is provided on a mandril on the main shaft (6) for returning the lever (2) to its original position. A detent wheel (8) with at least one detent lever (10) is mounted on the main shaft (6) to provide the detent torque required to hold the main shaft (6) in position when the lever (2) returns to its original position. A pair of support brackets (11) are provided for supporting and holding the said components together in an assembly.