Mobile apparatus for determining the lateral position of a railroad track

Claim 1

A mobile apparatus for determining the lateral position of a railroad track with respect to an adjacent railroad track without physical contact with the adjacent railroad track and for indicating the determined lateral position, the adjacent railroad track having a rail including a rail head, which comprises (a) a carriage mounted for movement along the railroad track, (b) a laser beam emitting and receiving instrument mounted on the carriage for focussing on the adjacent railroad track to measure the distance thereof from the instrument, the instrument having coincident optical axes for emitting and receiving the laser beam, said axes being focussed at an angle on the rail head and said axes extending in a transverse plane perpendicular to the track, (c) means for indicating the measured distance, (d) a signaling device connected to the laser beam emitting and receiving instrument and responsive to a deviation of the measured distance from a desired distance of the adjacent track, (e) a signal emitter indicating the angle, (f) computer means connected to the instrument and to the signal emitter for determining at least the horizontal distance from the instrument to the rail head, (g) a comparator unit connecting the signaling device to the computer means, the comparator unit being pre-adjusted to store admissible maximum and minimum distances to the adjacent railroad track, (h) a drive for reversibly pivoting the optical axes of the instrument in the perpendicular plane, and (i) a control unit connected to the computer means for reversing the drive to pivot the optical axes of the instrument in an opposite direction after the distance has been measured, the control unit being responsive to sudden changes in the measured distance.