Abstract: A reversing chain-operated, dual carriage train indexer is provided with a chain tension control that acts directly on the chain and a retraction-biased, two-position carriage connection cylinder in conjunction with a spring biased linkage system allows indexer operation in either direction with dogs up or down in dual force ranges controlled by the chain tension control.

Abstract: The present invention provides a low clearance, compact guideway, train positioning system that can be installed in close quarters alongside an existing railroad track. The system is chain driven and features an improved over/under or vertical sprocket carriage drive system in which parts normally exposed to the elements are protected while, at the same time, horizontal space requirements alongside the track are reduced. The system employs a vertically oriented chain drive which employs enclosed vertically mounted drive and idler sprocket units and a chain tube enclosing the lower chain strand which further minimizes exposure of the mechanism chain to the elements by totally enclosing the lower chain path in the over/under arrangement.

Abstract: A dog carriage for a railway car indexing system for positioning a railway car or a trip of coupled railway cars having railway wheels mounted in and carrying bogey wheel truck frames by engaging and pushing against the bogey wheel truck frames using dogs includes a dog carriage frame moveable along a railroad track, a pair of spaced opposed dogs pivotally attached to the dog carriage frame for pivoting between a lowered position and a raised position to engage a bogey wheel truck frame in the raised position by movement of the dog carriage frame. A bogey wheel truck frame sensing device is carried on the dog carriage and a dog operating system is provided for controlling the position of each of the dogs individually between the lowered and the raised position.