Abstract: A lump breaker apparatus for a rotary car dumper includes a porous barrier means in the form of a grizzly element, having sized openings therein and positioned in the flow path of the discharged bulk material prior to its entry into the hopper pit. Motorized impact means, preferably rotatable drum means, having a plurality of outwardly protruding striking elements, is mounted on the frame of the rotary dumper, extending between the end plates thereof and moveable with the frame. The impact means is selectively activated to engage and breakup lumps of oversized bulk material retained on the grizzly during a dumping cycle.

Abstract: A clamp for securing a railroad car in a rotary car dumper includes a guide pipe member mounted adjacent the section of track carried by the rotatable dumper frame, a clamp pipe member telescopically mated with the guide pipe member and a clamping jaw member extending laterally from the free end of the clamp pipe member toward the track section. Releasable coupling means in the form of a longitudinal slot in one pipe member which is engaged by a radially extending guide bar member tack welded or bolted to, or inserted in a slot in, the other pipe member permits the clamp pipe member to be extended and retracted relative to the guide pipe member by a coaxially mounted hydraulic cylinder while resisting rotational movement therebetween. If excessive torque is applied to the clamp pipe member, such as when the clamping jaw member is struck by a moving car, the guide bar member is sheared and the clamping pipe member rotates to swing the clamping jaw member out of the path of the car.