Abstract: A railroad frog assembly is provided with a spring wing rail multi-position holdback subassembly that continuously retains the spring wing rail in each spring wing rail open position when activated by the wheels of a railcar traversing the frog assembly, and that automatically deactivates the multi-position holdback subassembly and releases the spring wing rail from retention in an open condition and for complete closing after the last railcar wheel has passed through the frog assembly.

Abstract: A conveyor system comprising a track along which a plurality of carriers are movable. Each carrier includes a pusher dog that is movable into and out of position for engagement by a pusher lug of a conveyor chain. Each carrier is provided with wheels, and a pivoted anti-back up cam member which is normally urged by gravity in a direction to hold surfaces thereof out of engagement with the track. Each carrier further includes an actuator operable when it engages a preceding carrier or an obstacle to move the pusher dog out of engagement with the pusher lug. A spring is provided between the actuator and the anti-back up cam member so that when the actuator is operated to move the pusher dog, the cam member frictionally engages the track.

Abstract: An improved pawl and ratchet mechanism is disclosed wherein at least one of a plurality of pawl elements movably disposed within a housing is movable into a least one of the spaces between the teeth of a toothed track ratchet irrespective of the location of the housing with respect to the toothed track ratchet when the housing engages the toothed track ratchet. The improved pawl and ratchet mechanism may be used to contain explosive forces resulting from a pressure failure during the hydraulic testing of pipe.