GB560678A - A fluid-operated pressure-applying tool - Google Patents

Abstract

560,678. Hydraulic presses. MILES, J., and NISSIM, R. Oct. 8, 1942, No. 14168. [Class 69 (ii)] In a fluid-operated pressureapplying tool in which lowpressure fluid is applied to one face of a differential piston, the approach stroke of the ram is effected at substantially the same pressure from a large area of the other face of the piston, and the power stroke is effected at increased pressure from the free end of the piston stem. In the form shown, compressed air, steam, gas or other compressible fluid, is supplied at 11 to one side of a differential piston 13, the other side of which is separated by oil, water, or other incompressible fluid 15 from a second piston 16. Downward movement of the piston 13 forces the oil 15 through a port 18 and passage 19 in the piston stem 20 into a chamber 21 causing a differential ram 23 to approach the anvil 25. Increased pressure of the oil 15 then displaces the piston 16, and, when the port 18 is closed by a valve 28 on the piston 13, the latter moves as a unit with the stem 20 to increase the pressure on the ram 23 for the power stroke. When the supply at 11 is cut off, the return stroke is effected .by springs 14, 17, 24, 30. Two or more such differential pistons may be arranged in series. In a modified form the tool head is connected to a pressure multiplier by flexible cables, the pressure being partially multiplied in the multiplier, and again multiplied in the tool head. The initial pressure retracts the ram, the partially multiplied pressure causes its approach stroke, and the full pressure causes the power stroke. The multiplier includes a pair of telescopic differential pistons arranged in parallel.