Abstract: A hydraulic cylinder is provided which allows for a mount plate, or the like, to be moved between three positions. The mount plate can be positively positioned in any one of three different positions by appropriately supplying or removing pressurized hydraulic fluid to hydraulic fluid ports on the cylinder. The provision of appropriate positive stops corresponding to each desired position avoids the necessity for complex and/or expensive hydraulic control mechanisms. The cylinder is believed to be particularly suited for performing piercing operations, involving a negative pierce, in hydro-forming operations.

Abstract: A telescoping hydraulic hoist with tube stages formed from a heat treated aluminum alloy from one of the series 2000, 6000 or 7000 aluminum alloys. These alloys retain good “memory” properties, and under the force of a pressure spike undergoes a momentary elastic deformation which acts as a shock absorber, expanding the tube wall to absorb the peak stresses and resist buckling. The hoist of the invention is thus much lighter than a comparably rated steel hoist, and much more resistant to corrosion.