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Grade monitoring and steering apparatus

  • US 4,438,820 A
  • Filed: 11/16/1981
  • Issued: 03/27/1984
  • Est. Priority Date: 11/16/1981
  • Status: Expired due to Fees
First Claim
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1. Apparatus for monitoring the grade of pipe casing being laid in a bore underground simultaneous with said bore being cut of the type which includes a cutting head carried by a casing head attached to the front of said casing, means for steering said casing head up or down to correct the grade of the bore, and means for pushing said casing through said bore as it is formed, said apparatus comprising:

  • a grade sensor including a reservoir for containing a fluid medium at a predetermined level and adapted for being carried by said casing head;

    a light source carried in said reservoir arranged to transmit light through said medium;

    a light detector carried in said reservoir opposite said light source for detecting the intensity of said light received through said medium having an output representing said light intensity;

    whereby changes in the intensity of light detected due to changes in the inclination of-said sensor and of said level of medium may be utilized to produce indications of deviations in grade of said casing head and said steering means may be adjusted to return said casing head to grade.

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