1. Field of the Invention
This invention, in its preferred form, relates to motor-operated hand tools and, in particular, a hand tool for tightening and loosening threaded fasteners and the like. More specifically, the tool can be used with any portable, commercial-type drill motor. The tool reduces the speed of the drill motor and is capable of reversing the sense of rotation of the output spindle, while the input spindle always rotates in a clockwise direction.
2. Description of the Prior Art
Tools for tightening fasteners have long been known, as shown in U.S. Pat. Nos. 3,041,902 to Wing, 3,331,269 to Sauter et al., and 3,696,693 to Bosten et al. The tool disclosed by Wing comprises a motor and a simple speed-reduction planetary gear train whose output shaft provides the torque to tighten the fastener. The tool disclosed by Sauter et al. comprises a power section and a drive train which uses two-stage speed reduction. A set of differential bevel pinions is coupled to the power section. The output of the bevel pinions drive a planetary gear train whose output is used to tighten the fastener. The tool disclosed by Bosten et al. comprises a motor, a simple two-pinion gear set driven by the motor, and an output shaft driven by the gear set. The motor shaft and the output shaft are parallel. The motor is located inside the housing in all of these tools.
All of these tools suffer from the primary disadvantage that they can only be used for tightening fasteners, and not for also loosening them. Moreover, they can only be used with specific types of fasteners. Incorporation of the motor into the tool housings limits the use of the motor, while making the tools very expensive. Also, their many moving parts make them subject to breakdown. Apart from these common problems, the tool disclosed by Wing has too low a speed reduction, and the tool disclosed by Bosten et al. requires that the fastener be held against rotation while the tool is used to tighten its retainer.