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Electric screwdriver

  • US 4,878,404 A
  • Filed: 09/14/1988
  • Issued: 11/07/1989
  • Est. Priority Date: 09/14/1988
  • Status: Expired due to Fees
First Claim
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1. An electric screwdriver comprising a housing securing therein a motor, a power output end rotatably mounted said housing and driven by said motor, a control hollow cylinder having a first end secured to said housing and a second opposite end, an active shaft connected to said power output end and rotatably mounted in said control cylinder, a cap hollow cylinder, a torsion-adjusting hollow cylinder mounted between said cap cylinder and said second opposite end, a driver mounting piece axially slidably mounted in said cap and torsion-adjusting cylinders, a following shaft mounted between said mounting piece and said active shaft for transmitting a rotating power from said active shaft to said driver mounting piece, and a spiral spring mounted between said cap and torsion-adjusting cylinders for providing a spring force against said following shaft, characterized in that:

  • said mounting piece has an engaging end, which is the end engaging with said following shaft, attaching thereto a flange;

    said control cylinder mounts thereon a photic control switch electrically connected to said motor to emit a light to de-energize said motor; and

    said flange attachs thereon a light-shielding piece shielding said light to energize said motor when said mounting piece mounts thereon a driver urging against a screw.

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