944,780. Rolling. MASSEY SCHLATTER A.G. June 8, 1962 [June 13, 1961; Feb. 2, 1962], No. 22335/62. Heading B3M. [Also in Division B5] An overload safety device comprises a component which is maintained in rigid relation to one roll of a rolling mill by means of internal hydraulic pressure, which is suddenly and quickly released when exceeded by an external force on the component proportional to or equal to the force between the two rolls of the rolling mill, opening a valve comprising the component and a coacting member against the internal pressure. The Figures show two embodiments used on presses. Oil pressure in a cylinder space 12 (Fig. 1), is maintained by a pump or accumulator at about 800 atmospheres. This pressure acts on a hollow plunger 3, sliding in a cylinder 2 and pulls on a spindle 5 screwed into plunger 3, so that a head 8 of the plunger seats on an upper face 9 of the cylinder 2. When the force on face 21 of the plunger 3, resulting from the pressing operation, is sufficient, the plunger is forced up, breaking the seal between head 8 and face 9, and the oil enters a reservoir 23 through a gap 14. On removal of the oil pressure supplied to space 12, a small air pressure maintained through a pipe 24 restores the status quo. The plunger is adjustable relative to the cylinder by rotating the spindle 5 through a gear train comprising pinions 17, 19 and teeth 16 on the head 8. High oil pressure in a cavity 25 helps to maintain plunger 3 rigid relative to cylinder 2 during pressing &c. In an alternative embodiment (Fig. 3), a plunger 3<SP>1</SP> is rigidly connected to a carriage 1<SP>1</SP> of a press in which a hollow cylinder 2<SP>1</SP> slides. Oil pressure is maintained in a cylinder space 12<SP>1</SP> by a pump 35 through a bore 34, until pressure on face 211 forces open the seal between a conical surface 32 of head 8<SP>1</SP> of the piston and face 9<SP>1</SP> of a bushing 6<SP>1</SP> on the cylinder. The device may be reset by a weak spring 42 as shown, or reservoir 23<SP>1</SP> may be sealed by an annular plate 45 and a small air pressure maintained therein, tending to depress cylinder 2<SP>1</SP> after the oil pressure is removed.