GB189261A - Improvements in power presses - Google Patents

Abstract

189,261. Massey, Ltd., B. & S., and Massey, H. F. Sept. 6, 1921. Presses; l i m i t i n g stroke of press; relief and safety devices for; ram retracting-devices; pressure-producing apparatus; working valves.- A press ram or head 21, Fig. 1, is caused to perform its working stroke by means of a piston 24 operated from a cam, crank, eccentric, &c., and working in an hydraulic cylinder formed in the ram, ports 28, 29 being closed by a valve 30. When the ports are opened, the piston reciprocates idly in the ram, which is retained at the top of its stroke by springs or b a 1 a n c e weights, the top position being determined by an adjustable stop 44. The valve-operating mechanism comprises a pedal-operated lever 40 carrying set-screws 42, 43 and levers 37, 32. In the event of excessive pressure, a spring controlled plunger 50 opens the valve by means of collars 531. In a modified form, the hydraulic cylinder is closed by a cover constituting an oil reservoir 551, Fig. 10, a safety valve 73 is provided, and the valve 30 is disposed in the ram. During the upstroke the valve is opened by a lever 37 contacting with a trip 60 carried by the adjustable stop 44, being afterwards closed in the top position by a finger 631 on a cam-operated lever 63. The lever passes through a slidable rod 64, which may be withdrawn from the cam by a pedaloperated lever 70 so that the valve remains open. In a further modification, the ram 21 is arranged in a fixed cylinder 77, Fig. 18, communicating with the cylinder of the piston 24.