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Shaft lock arrangement for a power tool

  • US 5,191,968 A
  • Filed: 09/23/1991
  • Issued: 03/09/1993
  • Est. Priority Date: 09/23/1991
  • Status: Expired due to Term
First Claim
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1. A shaft lock arrangement for a power tool, the power tool including a housing, a motor mounted in said housing, said motor having a shaft, and a main switch mounted in said housing and controllable for selectively applying power to the motor for rotating said shaft, said arrangement comprising:

  • a flatted portion of said shaft;

    a secondary switch in series with said main switch, said secondary switch having a first contact and an actuator arranged for movement toward and away from said first contact to close and open, respectively, said secondary switch, said actuator being yieldably biased to maintain said secondary switch in its open state;

    a lock bar mounted for movement in said housing between first and second positions, said lock bar being formed with an open slot so dimensioned to prevent rotation of said shaft when the flatted portion of said shaft is within said slot, said flatted portion of said shaft being within said slot when said lock bar is in said first position and outside said slot when said lock bar is in said second position; and

    an actuator arm mounted on said lock bar and arranged so as to engage said secondary switch actuator and place said secondary switch in its closed state when said lock bar is in its second position with said flatted portion of said shaft outside said slot and free to rotate, said actuator arm releasing said secondary switch actuator when said lock bar is moved from said second position toward said first position to allow said secondary switch to assume its open state.

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