Pneumatic rotary drive

A pneumatic rotary drive comprising a housing, at least one cover sealingly closing the housing in a pressure medium-tight manner, a rotatable shaft extending out of the housing through the at least one cover, at least one guide member mounted in the housing, a belt having an external toothing mounted in the housing in engagement with the shaft and extending around the at least one guide member, the belt having first and second length portions in contact with each other, such that the belt defines two expandable pressure chambers, a pressing member for pressing the first and second length portions together in a pressure medium-tight manner, means for admitting pressure medium to the pressure chambers, such that the belt is rotated when pressure medium is admitted to one of the pressure chambers so as to expand the pressure chamber, the belt having two ends, the two ends being mounted adjacent each other in a common plane, the two ends forming the first length portion being pressed by the pressure member against the second length portion, the housing having an inner wall, the inner wall having a toothing in engagement with the external toothing of the belt.