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Method for detecting a bit jam condition using a freely rotatable inertial mass

  • US 7,395,871 B2
  • Filed: 04/22/2004
  • Issued: 07/08/2008
  • Est. Priority Date: 04/24/2003
  • Status: Expired due to Fees
First Claim
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1. A method for detecting a bit jam condition in a power tool having a tool drivably connected to a motor to impart rotary motion about a rotational axis to the tool, comprising:

  • disposing an inertial mass comprised of a solid cylindrical body in a housing of the power tool, the inertial mass being freely rotatable about its longitudinal axis and axially aligned with the rotational axis of the tool;

    monitoring rotational motion of the housing of the power tool in relation to the inertial mass; and

    determining when angular velocity of the rotational motion exceeds a predefined velocity threshold indicative of a bit jam condition.

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