1. In a rotary car dumper having a rotatable frame to support a car for rotation between an upright position and a dump position and having a carriage which can be clamped to the frame in a selected position, the combination comprising a clamp beam mounted to the carriage for limited vertical movement with respect thereto, a yoke secured to the carriage and having a pair of arms extending outwardly over the clamp beam, and at least one spring interposed between each yoke arm and the clamp beam to urge the clamp beam to one extreme position with respect to the carriage.

2. In a rotary car dumper having a rotatable cradle to support a car for rotation between an upright positiOn and a dump position and having a carriage which can be clamped to the cradle in a selected position, the combination comprising a clamp beam mounted to the carriage for limited vertical movement with respect thereto, said clamp beam extending over the body of the car for clamping contact therewith, a yoke secured to the carriage and having a pair of arms extending outwardly over the clamp beam, and at least one compression spring interposed between each yoke arm and the clamp beam to urge the clamp beam to one extreme position with respect to the carriage.

3. In a rotary car dumper having a rotatable cradle with means to support a car in a predetermined position in the cradle for rotation between an upright position and a dump position, the combination comprising a carriage slidably mounted on the cradle, said carriage having a transverse member extending over said predetermined car position, means to clamp said carriage in a selected position, a clamp beam mounted to said transverse member for limited vertical movement with respect thereto, said clamp beam extending across the entire width of the car for clamping contact therewith, a yoke pivotably secured to the transverse member in a substantially centered position with respect to said predetermined car position, said yoke having a pair of arms extending outwardly over the clamp beam, and two compression springs mounted, respectively, between said yoke arms and said clamp beam to urge the clamp beam to its lowermost position with respect to said transverse member, said clamp beam yielding upwardly against the force of said springs as the car rises in the cradle after a load is dumped.

4. In a rotary car dumper having a rotatable frame to support a car in a predetermined position for rotation between an upright position and a dump position, the combination comprising a carriage, means to clamp the carriage on the frame in a selected position, a clamp beam mounted on said carriage for limited vertical movement with respect thereto, said clamp beam extending across the entire width of a car in said predetermined position for clamping engagement with both sides thereof, means on said carriage to support a pair of springs, and a pair of springs mounted between said support means and said clamp beam to urge the clamp beam to its lowermost position with respect to said carriage for yielding movement of the clamp beam against the force of said springs as the car rises after the load is dumped therefrom.