GB529624A - Control for power hammers - Google Patents

Abstract

529,624. Power hammers. MURRAY, G. R., and CLARKE, E, C. June 5, 1939, No. 16450. Convention date, April 25. [Classes 122 (ii) and 122 (iii)] The valve controlling the supply of fluid to the operating cylinder of a power hammer may be selectively alternated by either of two adjustable cams operated by the ram, one cam causing the hammer to reciprocate continuously and the other causing it to make single strokes only. In one form, Fig. 3, the valve actuating rod 22 is connected to the short arm 21 of a bell crank lever, the long arm 27 of which forms the cam, co-operating with the hammer ram 23, for causing the latter to make single strokes only. The bell-crank lever is pivoted to one end 19 of a lever 20 pivoted at 24 and connected at its other end by a rod 26 to a hand lever 25 by which the valve is manually controlled. The cam 29 by which the hammer may be caused to operate continuously, comprises a blade engaging in a slot in the arm 27 and adjustably connected at its ends to a lug 31 on the arm 27 and a slotted lug 35 on the arm 21. By this connection the blade may be adjusted vertically and may be withdrawn fully into the slot of the arm 27 so as to be inoperative. In a modification, the lower end of the blade 29 is non-adjustably pivoted to a lug on the arm 27. In other modifications, the blade 29 is replaced by a spring strip fixed at its lower end to the arm 27 and slidable at its upper end through a guide .on the arm 27. At a mid-part of its length it is engaged by a cam or lever connected by a toggle device to the arm 21. In one position of the toggle, the strip is bowed to project beyond the face of the arm 27 to form an active cam surface and in the arm 27 to form the operative surface thereof. Instead of a toggle device the strip may be connected by links to a hand lever which may be held in either of two positions according to which cam is to be operative. In another form, the blade 29 is replaced by a member of U- section embracing the arm 27, the edges of the U forming the operative cam surface. It may be held in operative position against the action of a spring, by a pin passed through holes in the arms of the U and lying in front of the arm 27. The ram 23 is provided with a bearing face for co-operating with the cams and to prevent unbalancing of the ram due to the provision of this face. a similar face may be provided on the diagonally opposite position on the ram, The hand lever 25 is pivoted to a yoke 70 swivelled on a fixed bracket 69 and is connected by a link 73, guided in the yoke 70 to a second yoke 76 having a cross member 80 in which the lower end of the rod 26 is threaded and adjustable by nuts 81, 82. By this adjustment, the height of the. cams relatively to a determined position of the hand lever 25, and thus the position of the ram when the lever is in its neutral position can be adjusted. A bush 78 fixed to the rod 26 and guided in the cross member 77 of the yoke, may have scale markings to facilitate the adjustment of the rod. To prevent too rapid movement of the hand lever 25, a dash pot 83 fixed to the yoke 70 may have its piston rod 85a detachably secured by a pin 88 to an arm 87 fixed to the link 73.