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Automatic steering for construction machines

  • US 4,140,193 A
  • Filed: 04/25/1977
  • Issued: 02/20/1979
  • Est. Priority Date: 04/25/1977
  • Status: Expired due to Term
First Claim
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1. A construction machine comprising:

  • a main frame;

    ground engagement means disposed from said main frame to support and transport said machine along a path of travel;

    a pair of said ground engagement means being disposed at opposite front corners of said main frame and rotatably connected thereto on individual steering axles;

    power means to individually turn each of said front ground engagement means about its respective steering axle;

    a steering sensor associated with one of said front ground engagement means and adapted to produce a steering voltage on either side of a null point indicating the magnitude and direction of a change in the path of travel of said machine from a reference extending along the path of travel;

    steering detector means associated with each of said front ground engagement means including a rotatable member adapted to turn with the respective steering axles of each of said ground engagement means;

    said steering detector means for said one front ground engagement means having a first feedback potentiometric means operably connected to its rotatable member for rotation in synchronism therewith to produce a first feedback signal and a second potentiometric means to produce a slave signal;

    said steering detector means for said other front ground engagement means having a second feedback potentiometric means operably connected to its rotatable member for rotation in synchronism therewith to produce a second feedback signal;

    and electrical means to receive said voltage signal from said steering sensor and produce an amplified power signal to control said power means to turn said one ground engagement means about its steering axle and to receive said slave signal and produce a second amplified power signal to control said power means to turn said other ground engagement means about its steering axle;

    said electrical means being further adapted to receive said first and second feedback signals to change the null point of said steering sensor by the same amount and degree of steering correction and thereby incremently control both of said power means following said null point of said steering sensor and thereby turn said pair of ground engagement means in synchronism about their respective steering axles.

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