Abstract: The retarder is installed adjacent a railway track for reducing the speed of a wagon rolling along the track and additionally has the capability of boosting the speed of a wagon. The retarder includes a hydraulic unit having a portion adapted to be deflected out of the path of a wheel of the wagon when directly or indirectly engaged by the wheel before returning to its original position. The unit has adjustable hydraulic damping capable of resisting such deflection to retard the wagon, and a wagon speed responder for adjusting the hydraulic damping of the unit to retard a wagon travelling at high speed.

Abstract: A retarder, suitable for reducing the speed of a wagon rolling along a railway track, includes a retainer, which is adapted to be secured upon or adjacent a rail of the track, and an hydraulic unit which is fitted in the retainer. A portion of the unit normally projects from the retainer thus to lie in the path of a wheel of the wagon so as to be engageable by that wheel. The portion is movable inwardly of the retainer to a position, out of the path, in which it permits the wheel to pass the retarder. The retarder includes holding mechanism for maintaining the portion in that position.