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Piping travelling apparatus

  • US 4,770,105 A
  • Filed: 08/04/1986
  • Issued: 09/13/1988
  • Est. Priority Date: 08/07/1985
  • Status: Expired due to Fees
First Claim
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1. A piping traveling apparatus, comprising:

  • a frame;

    a plurality of continuous treads mounted for rotation on said frame so that at least a portion of each tread is disposed outside said frame to drive the frame as the treads rotate in contact with an inner wall surface of the piping;

    drive means including at least one motor and transmission gearing coupled between said motor and said continuous treads for driving said treads in rotation;

    continuous tread biasing means for forcing said plurality of continuous treads outwardly of said frame so as to be pressed into contact with the inner wall surface of the piping;

    control means for remotely controlling said continuous tread biasing means so as to selectively vary the outward force applied to said continuous treads to vary the contact pressure between said continuous treads and the inner wall surface of the piping as said apparatus;

    wherein said continuous tread biasing means comprises spring holder means mounted on said frame and means including at least one coil spring supported by said spring holder means for biasing said continuous treads, said coil spring being formed of a shape memory alloy, and wherein said control means comprises heating means for selectively heating said coil spring to control the biasing force thereof.

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