GB1028531A - Rotary hammer - Google Patents

Abstract

1,028,531. Drilling. BLACK & DECKER MANUFACTURING CO. Feb. 22, 1963 [July 30, 1962], No. 7183/63. Headings B3B and B3C. [Also in Division B4] A rotary-percussive drill comprises a ram 62 reciprocable in a barrel 16 by means of a crank 37 and a tool socket 100 having a gear 94 thereon driven by a pinion 76 which is loosely mounted on a shaft 71 and engageable therewith via a clutch 78, 79, 80. The crank 37 is rotated by an electric motor 11 via gears 36, 42 and connected with a piston 61 by means of a rod 60, cross-head 58 and connecting rod 55, the piston being reciprocated within the ram 63 so that air trapped within a chamber 64 causes the ram to rapidly strike the end 104 of a tool bit 101; the motor also drives the shaft 71, via gears 43, 53, 52, 72. The socket 100 is of hexagonal shape and formed in a sleeve 97 connected to the gear 94. A further hexagonal socket 110 is formed in a nose piece 19. In operation, if it is desired to rotate and hammer the tool bit, the latter is formed with a shape as shown in Fig. 13, in which the hexagonal end 104 of the bit extends into the cylinder 59 for the ram 62 so that the end is struck while it is rotated by the sleeve 97 and gears 80, 94. When rotary drilling only is required, a tool bit having an hexagonal end 104 which does not project beyond the sleeve is provided so that the end cannot be struck by the ram; during this type of drilling the ram is held at the forward end of the cylinder by a split collet 88, Fig. 17 (not shown). When hammering only is required a tool bit is fitted which instead of the end 97 being hexagonal so that it is rotated, the end is made circular thereby allowing the sleeve to rotate without turning the bit; in order to prevent any possible rotation due to friction, a portion of the bit is formed with a hexagonal shape so as to fit the socket 110, Fig. 15 (not shown). The clutch may be adjusted so that it will slip if the tool is overloaded.