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Loosening prevention screw

  • US 5,569,009 A
  • Filed: 11/23/1993
  • Issued: 10/29/1996
  • Est. Priority Date: 11/26/1992
  • Status: Expired due to Fees
First Claim
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1. A loosening prevention screw comprising:

  • a main thread for driving the screw into a hole; and

    a sub-thread running in the same direction as the main thread, being smaller in outer diameter than the main thread, and having a pitch different from that of the main thread;

    wherein the main thread and the sub-thread are formed over substantially a same longitudinal distance on a same shank of the screw, and;

    wherein the pitch of the main thread is coarser that the pitch of the sub-thread.

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