Mobile track working machine

In a mobile apparatus for working on a track including two rails fastened to ties, which comprises a track lining and leveling unit having a frame mounted for mobility on the track rails, hydraulic drive means for moving the frame in mutually perpendicular directions extending transversely and vertically to the track for lining and leveling the track, flanged lining rollers mounted on the frame for engagement with an associated one of the rails, and power-actuated rail lifting hooks mounted on the frame and arranged to subtend the rails, the improvement of

• 1. a hydraulic adjustment drive for continuously and simultaneously moving the lining rollers into substantially play-free engagement with the associated rails, the drive comprising
• a. a cylinder housing a piston dividing the cylinder into two chambers, and
• b. two conduits respectively connected to the cylinder chambers;
• and
• 2. a control for the adjustment drive for temporarily holding the lining rollers in a fixed relation to the frame, the control comprising
• a. a source of hydraulic fluid,
• b. a hydraulic fluid delivery line leading from the fluid source and a hydraulic fluid return line leading to the fluid source, and
• c. a valve means controlling the pressure fluid actuation, the two conduits of the adjustment drive being connected to the control valve means, and the valve means comprising an adjustable valve and check valve means, the adjustable valve being arranged for selective connection of one of the conduits to the hydraulic fluid delivery line and of the other conduit to the hydraulic fluid return line, and the check valve means being arranged to prevent hydraulic fluid flow from the cylinder chamber receiving hydraulic fluid from the delivery line.

In a mobile apparatus for working on a track including two rails fastened to ties, which comprises a track lining and leveling unit having a frame mounted for mobility on the track rails, hydraulic drive means for moving the frame in mutually perpendicular directions extending transversely and vertically to the track for lining and leveling the track, flanged lining rollers mounted on the frame for engagement with an associated one of the rails, and power-actuated rail lifting hooks mounted on the frame and arranged to subtend the rails, the improvement of

• 1. a hydraulic adjustment drive for continuously and simultaneously moving the lining rollers into substantially play-free engagement with the associated rails, the drive comprising
• a. a cylinder housing a piston dividing the cylinder into two chambers, and
• b. two conduits respectively connected to the cylinder chambers;
• and
• 2. a control for the adjustment drive for temporarily holding the lining rollers in a fixed relation to the frame, the control comprising
• a. a source of hydraulic fluid,
• b. a hydraulic fluid delivery line leading from the fluid source and a hydraulic fluid return line to the fluid source,
• c. pump means for delivering hydraulic fluid under pressure from the hydraulic fluid source into the delivery line,
• d. a branch line connecting one of the conduits to the delivery line,
• e. a check valve in the branch line preventing backflow of hydraulic fluid to the delivery line from the cylinder chamber connected to the branch line,
• f. another branch line connecting the other conduit to the return line, and
• g. a multi-way valve in the other branch line.