GB485396A - Improvements in or relating to presses - Google Patents

Abstract

485,396. Mechanical presses. JACKSON, C. E., and HUNT, T. J. Dec. 8, 1936, No. 33631. [Class 87 (ii)] In a power-operated press, the ram a, Fig. 1 counterbalanced by weights b carries a rack e engaged by a pinion on a shaft d ; to bring the ram into preliminary engagement with the work the shaft d is rotated by the hand wheel c or by auxiliary power means such as a low pressure air cylinder or solenoid. The shaft d also carries a disc f, Fig. 2 ; a block h is rotatable about the axis of the shaft and has pivoted thereto at l a lever k one end of which is formed as a pawl m to engage ratchet teeth g on the disc, the other end of the lever being connected to the head n of the piston-rod p of a compressed air or hydraulic cylinder q ; when the power means is at the end of its return stroke, the block h is held by a spring j against a stop h<1> and the lever k abuts a stop r on the block, whereby the pawl m is held out of engagement with the teeth g so that the shaft can be rotated to effect the approach stroke ; the power cylinder is supplied with pressure fluid through a reducing valve in the supply line and under the control of a valve operated by a pedal s ; during the first part of the stroke of the power means the pawl m is rocked into engagement with the teeth on the disc, and for the remainder of the stroke the disc and therefore the shaft are rotated to effect the pressing stroke. Alternatively the pawl may be replaced by a cam surface and the disc have an unbroken peripheral surface, one of the surfaces having a friction covering. The power means may be fluid-pressure operated or electrical, as, e.g. a solenoid.