Track levelling and tamping machines

Claim 1

In a track levelling machine, a main vehicle including a front vehicle mounted on track rails, said front vehicle mounting a vertical staff for each rail, each staff having sighting elevation marks thereon, a measuring unit associated with the main vehicle and mounted on the track rails independently of said main vehicle, the measuring unit including a platform tiltably carried by an axle transverse to the track rails, motor means for tilting the platform transversely to the track rails, a carrier platform supported by the platform, power means for lifting and tilting said carrier platform, an optical sighting device supported by the carrier platform above each track rail for sighting the elevation marks on the respective vertical staff on the front vehicle, a light beam transmitter in fixed relation with each optical sighting device, track adjusting members mounted on the main vehicle for engagement with the track rails to lift same, vertically adjustable control means for each track adjusting member adapted to respond to the light beam projected from the light beam transmitter to control the lifting action of each track adjusting member, power means for raising and lowering the aforesaid vertically adjustable control means, and measured valve control and transmitting means for transmitting signals to the power means for raising and lowering the vertically adjustable control means to determine the height at which the projected light beam strikes said control means to control the action of the track adjusting members.