Abstract: A settable slip clutch or coupling between a driving (1) and a driven (2) shaft includes balls (11) accommodated in recesses (3) on the driving shaft and in engagement with chambers (18) in the driven shaft. To achieve an unloading effect when the clutch slips, i.e. when the balls are urged from the recesses and into the chambers, thus disengaging the clutch, at least one of the chambers, e.g. (17) and/or (16) is made with a width which is at least 1.5 times as great as the ball diameter. For obtaining a reverse lock when rotation is reversed, this and/or those chambers can be made with a wall plane (7, 8) which is inclined (.alpha.) relative to the normal wall plane direction. Alternatively, a further chamber (15) may have an opening (12) in its one wall to serve as reverse lock.

Abstract: A tap holder e.g. for threading taps, has a drive body (1) intended for connecting to the chuck of a drive motor. The driving power is transferred by a torque-limiting device (2, 9, 11) to a clamping body (8) intended to clamp the shank (12) of the threading tap. By the clamping body having outer (6) and inner (5) jaws with an intermediate elastic member (7), tool shanks of different dimensions may be accommodated by the clamping body.