In a hydraulic scrap shearing machine having scrap shears at one end of an open feed channel which is wider than the mouth of the shears and which has one of its opposite side walls movable towards the other to squash scrap placed in the feed channel to a final width which will allow the scrap to be pushed by a feeder ram along the feed channel and into the mouth of the shears, the movable side wall is formed by the working faces of a main hydraulic ram and an auxiliary hydraulic ram which can be advanced independently of the main ram, the working face of the auxiliary ram being situated adjacent the mouth of the shears and being shorter than the working face of the main ram measured in the direction of the feed channel. Normally the main and auxiliary hydraulic rams are operated so that their working faces, together forming the whole of the movable side wall, are advanced and retracted together. However, if this operation fails to squash sufficiently the scrap in the feed channel, the auxiliary ram is operated so that its working face advances relative to the face of the main ram to squash further the scrap in the region adjacent the mouth of the scrap shears.