GB1120159A - Impact wrench having improved camming means - Google Patents

Abstract

1,120,159. Impact wrenches. CHICAGO PNEUMATIC TOOL CO. 13 July, 1967 [31 Aug., 1966], No. 32376/67. Heading B3N. [Also in Division F2] An impact wrench comprises a sleeve 25 driven by a sliding vane pneumatic motor 22, a hammer 33 splined in the sleeve, a cam shaft 45 connected to the hammer through a ball clutch, and an anvil 38 slidably connected to camshaft 45 by a key 51, or splines. A rotary impact is delivered at every alternate revolution of the anvil. Shaft 45, Fig. 11, has a ball track 62 comprising a lobe 73 which gradually falls away to a deep portion 67 extending for about 180 degrees, and then gradually rises up to the lobe. A raceway 64, Figs. 10, 11, extends around the cam shaft adjacent track 62, and has a symmetrical wide area 74 which extends for about 80 degrees on each side of the lobe. A radial stop 77 is provided, and guides ball 65 from area 74 into portion 67. Area 74 of raceway 64 has a relieved section 83. A track 63 in hammer 33 comprises a lobe 79, and a rubber ring 84 in the hammer engages ball 65 at some stage in the operation. In operation, motor 22 drives hammer 33, and ring 84 rolls ball 65 along track 62 until it drops into relieved section 83, whereupon it drops away from ring 84, engages lobe 79, thus providing a drive through hammer 33, ball 65, shaft 45, and nut engaging socket 42. When the nut is tight, hammer 33 rotates relative to anvil 38, and is accelerated towards the anvil by the ball cam 65, so that jaws 35, 43 engage to produce an impact. The ball is moved over lobe 73 by lobe 79, and rolls into area 74 of track 62. Spring 36 returns the hammer to the Fig. 1 position, whereupon ring 84 rolls ball 65 axially out of area 74, and stop 77 guides the ball back into track portion 67. Lobe 79 rides over the ball at a faster rate of rotation than that of the ball, and completes one revolution without producing an impact. However, during the second revolution of the hammer, the ball has been rolled into area 83 by ring 84, so that an impact is produced. The wrench operates in a similar fashion when the motor is reversed. In a modification relieved section 83 on cam shaft 45 is replaced by two slots 87, 88, Fig. 18, connected by a groove 89.