Abstract: A pneumatic power wrench comprises a housing (10) with a pressure air supply passage (16), a motor (13) and an adjustable pressure responsive shut-off valve (17) located in the air supply passage (16) and including a valve element (21) and a bias spring (25) supported in one direction by the valve element (21) and in the opposite direction by a movable spring support (26), and a manually operated torque setting mechanism (31,32) for setting the spring support (26) in various positions, thereby varying the pre-tension of the spring (25) a swell as output torque level of the motor (13), wherein the setting mechanism (31,32) comprises an adjustment unit (32) which is rotatively journalled in the housing (10) and carrying two or more adjustable stop elements (31) arranged to be selectively brought into engagement with the spring support (26) and individually set at different positions corresponding to desired different output torque levels of the wrench.

Abstract: A reversible power wrench includes a housing (10), a rotation motor, and a power transmission coupling the motor to an output shaft (21), and further includes a reduction gearing (20) with first planetary gearing (28) for transferring torque in the "forward" direction of rotation and a second planetary gearing (29) for transferring torque in the "reverse" direction of rotation. The first and second planetary gearings (28, 29) have rotationally interconnected sun gears (31, 39) and a common planet wheel carrier (34).