Abstract: A down shift mechanism for incorporation in a device such as an assembly tool includes a wrap spring which locks and releases a planetary gear speed reduction assembly to provide shifts between two drive ratios in response to torque throughput. The wrap spring is received upon a drive drum within a cylindrical housing. The ends of the wrap spring are engaged by a pair of relatively rotationally adjustable and fixable spring engaging lugs which adjust the preload of the wrap spring and thus the torque level at which the spring unwraps and lifts off the drive drum and at which the shift occurs. The wrap spring housing is coupled to the ring gear of the planetary gear assembly. When the torque applied to the wrap spring exceeds the preload, the spring unwraps, unlocking the ring gear and planetary gear assembly and downshifting to the speed reduction determined by the planetary gear assembly. An alternate embodiment of the downshift mechanism is also presented.

Abstract: A down shift mechanism for incorporation in a device such as an assembly tool includes a wrap spring which locks and releases a planetary gear speed reduction assembly to provide shifts between two drive ratios in response to torque throughput. The wrap spring is received upon a drive drum within a cylindrical housing. The ends of the wrap spring are engaged by a pair of relatively rotationally adjustable and fixable spring engaging lugs which adjust the preload of the wrap spring and thus the torque level at which the spring unwraps and lifts off the drive drum and thus the torque level at which the shift occurs. The wrap spring housing is coupled to the ring gear of the planetary gear assembly. When the torque applied to the wrap spring exceeds the preload, the spring unwraps, unlocking the ring gear and planetary gear assembly and downshifting to the speed reduction determined by the planetary gear assembly. An alternate embodiment of the downshift mechanism is also presented.

Abstract: The assembly tool comprising an electrically operated clutch assembly and achieves rapid termination of energy throughput to provide accurate torque delivery for fastener tightening and similar applications. The clutch assembly includes a pair of equal diameter, axially aligned input and output hubs having a wrap-spring disposed thereabout. One end of the wrap-spring is coupled to the input hub and the other is coupled to a control annulus disposed concentrically and freely rotatably about the output hub. An electromagnet also concentrically disposed about the output hub is activated to couple the control annulus to the output hub. A resulting drag on the wrap-spring tightens it about the output hub and power is transmitted. Deactivation of the electromagnet provides rapid release of the wrap-spring and termination of power throughput. A one way (overrunning) clutch couples the hubs when power is applied in the opposite direction to, for example, facilitate removal of fasteners.

Abstract: An adjustable torque limiting assembly includes a first wrap spring mechanism which provides a readily adjustable torque transmission limit and a second coaxially disposed wrap spring mechanism which provides a mechanical signal that the torque limit has been reached. This signal may be utilized to terminate an energy supply to a prime mover associated with the torque limiting assembly. The first wrap spring mechanism generally includes a wrap spring in which the spring moment and thus the slip or overrunning torque threshold may be readily adjusted. The second wrap spring assembly likewise includes a wrap spring which is activated only subsequent to slip of the first wrap spring and enlarges to engage a concentrically disposed control sleeve. The control sleeve then rotates and activates an associated shut-off mechanism.

Abstract: A bi-directional, speed reducing mechanism for use with hand-held power tools comprises a pair of epicyclic gear trains mounted in a common carrier which each independently engage one of a pair of cages or ring gears disposed thereabout. The cages may alternately be locked in a stationary position or released for free rotation by independent activation of one of two identical wrap spring brakes disposed about each of the cages. The mechanism is contained within a generally cylindrical housing suitable for positioning between a conventional unidirectional power tool motor and gear head or powered device. In addition to the reversing capability, speed reduction in the range from 3.5:1 to 9:1 is also achieved by this mechanism.

Abstract: A reversible speed reducing mechanism for use with hand-held power tools comprises a pair of juxtaposed epicyclic gear trains mounted in a common carrier which independently engage a pair of cages or ring gears. The cages may alternately be locked to or released from an outer housing to accomplish the bidirectional transmission of rotational power. The complete reversing mechanism is housed in a generally cylindrical body suitable for mounting between a conventional unidirectional motor and gear head or powered device. Forward or reverse output rotation is selected by moving a control button positioned on the periphery of the reversing mechanism. Speed reduction in the range from 3 to 5 to 1 can be achieved by this mechanism.

Abstract: An adjustable torque limiting assembly includes a first wrap spring mechanism which provides a readily adjustable torque transmission limit and a second coaxially disposed wrap spring mechanism which provides a mechanical signal that the torque limit has been reached. This signal may be utilized to terminate an energy supply to a prime mover associated with the torque limiting assembly. The first wrap spring mechanism generally includes a wrap spring in which the spring moment and thus the slip or overrunning torque threshold may be readily adjusted. The second wrap spring assembly likewise includes a wrap spring which is activated only subsequent to slip of the first wrap spring and enlarges to engage a concentrically disposed control sleeve. The control sleeve then rotates and activates an associated shut-off mechanism.