Importance

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Abstract

Apparatus for indicating the change in position of a travelling block coupled to a wire line which is wrapped around a drum, comprising a motion pickup device responsive to the drum for providing a first shaft output having a fixed relationship to the rotation of the drum, an infinitely adjustable drive unit responsive to the first shaft output for providing a second shaft output having an adjustable relationship to the rotation of the drum, a pneumatic logic circuit responsive to the second shaft output for providing pulses that approximately coincide with each foot and each five-foot multiple of travelling block movement, and an output unit for displaying the foot and five-foot pulses. Calibration of the apparatus is accomplished by adjusting the drive unit to provide an average of the correct rate of travelling block movement relative to rotary motion of the drum.

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First Claim