Fig. 52 shows a press for heavy work. The diagram in Fig. 53 shows the interior features of the press.

This equipment consists of the press, the hydraulic intensifier, and the auxiliary water tank.

A piece of work W is pressed between the dies DD'. Different shapes of dies may be used. The press head H is forced down by hydraulic pressure on the ram P in the cylinder N, and is raised by steam pressure under the two pistons in the cylinders CC. The vertical motion of the press head is guided by the four colums G which conect the anvil with the entablature B and hold the press rigidly against distortion.

Water pressure of about 5500 lbs. per square inch is supplied through the pipe 0 from the steam intensifier which consists essentially of a steam cylinder J and a much smaller hydraulic cylinder K. Steam admitted under the piston in J communicates the pressure to the water in K through the rod L. Knowing the pressure per square inch of steam in J, the water pressure per square inch in the hydraulic system is found from the relation

Fig. 52. - Hydraulic Forging Press.

Steam pressure per sq. in. in J Area of end of plunger L

Water pressure per sq. in. in K Area of lower face of piston in J

A mechanism is fitted to shut off the steam automatically in case the water pressure in K is suddenly lost by any accident.

The entire working of the press is controlled by a single hand-lever ingeniously connected to control the valves numbered 1, 2, 3 and 4.

Fig. 53. - Diagram of Hydraulic Forging Press.

Valve No. 1 controls steam to the cylinder J, No. 2 controls exhaust from the cylinder J, No. 3 controls steam and exhaust from the cylinders CO, and No. 4 controls water to and from the tank T through the valve M.

The auxiliary tank T contains air and water under a pressure of 60 lbs. per square inch, and is used as a reservoir for supplying water to or receiving it from the main pipe 0. The plunger L may remain quiet and the press head may be lowered by allowing water to flow through the valve M from the pressure tank. Likewise, the press head may be raised by the cylinders CC, with the valve M opened to admit water to the tank against the tank pressure. The system is so arranged that when L moves upward the valve M will close, as great pressure must not be communicated to the tank T.