Apparatus for the non-contact measurement of a track gage

Apparatus for the non-contact measurement of the gage of a track comprising two rails having rail heads, which comprises

• (a) a machine frame extending in a longitudinal direction and equipped with undercarriages supporting the machine frame for mobility on the track and a wheel axle having wheels running on the track rails,
• (b) an optical sensor associated with each track rail and affixed to the wheel axle, each sensor being mounted on the wheel axle and pivotal about an axis extending in the longitudinal direction of the machine frame, and each sensor emitting a light beam capable of sensing the distance of the sensor from the associated rail without contact therewith, and
• (c) a stepping motor connected to each sensor for pivoting the sensor about said axis, the stepping motor and connected sensor constituting a closed control circuit for calculating an angular position required for focussing the light beam on a location of the associated track rail having a constant vertical position and correspondingly pivoting the sensor with respect to the associated track rail into the calculated angular position.