GB738951A - Rotary impact tool - Google Patents

Abstract

738,951. Slip clutches. CHICAGO PNEUMATIC TOOL CO. Nov. 19, 1953 [Jan. 5, 1953], No. 32096/53. Class 80 (2). [Also in Group XXII] A rotary impact tool comprises a rotatable anvil 37, having at least one jaw 38, resilient means 54 interposed between a driving spindle 30 and a hammer 40 to urge the hammer towards a normal position adjacent the anvil, and a driving connection between the spindle and hammer which constrains the hammer for relative helical movement when it is displaced from the normal position but permits independent circumferential movement when the hammer is in the normal position. A shaft 28, driven by a pneumatic or electric motor, rotates the spindle 30 through planetary gearing 24, 31. The rotational movement is transmitted from the spindle 30 to a cam sleeve 44 by balls 46 running in grooves 45 in the spindle. The rotation of the cam sleeve 44 is transmitted to the hammer 40 by balls 49 riding against surfaces 50H, Fig. 16C. There is a circumferential lost motion of 40 degrees between the spindle and cam sleeve represented by the portions 45C, Fig. 16C, the slots 45 and the portions 470 of recesses 47 in the sleeve. A further lost motion of 60 degrees exists between the cam sleeve and hammer represented by the portions 480 of recesses 48 in the sleeve and portions 500 of recesses 50 in the hammer. The lost motion ensures that the hammer delivers a blow to the anvil jaws 38 when it is travelling at its maximum speed. When the motor is reversed, for unscrewing a nut, the parts at first assume the positions shown in Fig. 16A. Thus the cam sleeve 44 forms, in effect, a part of the spindle when screwing-up and a part of the hammer when unscrewing.