The ends of the rod-like abutments (16) which extend across the bridge are mounted detachably fixed in dish-like holders (14,15) which open towards the lift cylinders (18,19). The holders preferably surround the abutments half way round their circumference. The abutments can be held by screw bolts (17) passing through said abutments and the holders. The end pieces (20) of the cylinders enclosing the abutments adjoin on the side remote from the free ends of the abutments a projection (21) on the abutment.
