GB318623A - Improvements in or relating to a portable machine having a selfcontained motor for boring, drilling, milling, screwing up nuts and like operations - Google Patents

Abstract

318,623. Aktiebolaget Nordiska Armaturfabrikerna. Sept. 8, 1928, [Convention date]. Motors, gearing for.-In motor-driven tools of the kind in which the tool is rotated by a variable and reversely acting torque, the maximum torque in one direction is greater than the maximum in the other direction and the mean torque in the first direction may also be greater than that in the second. The device may be used for boring and drilling, milling or screwing up nuts &c. and the driving torque is arranged to be larger than the resisting torque, but in the reverse direction less than the resisting torque in this direction. In one form, a casing 1 having a handle 2 supports the stator 3 of a motor whose rotor 4 is attached to a shaft 5 carrying a disc 6. Slots 11 in the disc receive the pivots 12 of rollers or balls 7 which are maintained by centrifugal force in contact with a casing 8 to which the tool shaft 9 is secured. The internal surface of the casing 8 consists of two outwardly diverging cam surfaces 10<1> and two inwardly extending surfaces 10<2>, the torque transmitted to the tool thus varying during each rotation and the maximum being greater than that of the motor. In a modification the slots 11 are curved and the cam surfaces are varied and in a further modification the disc 6 is dispensed with and the rollers 7 are mounted on approximately radial arms pivoted to the shaft 5. The Specification as open to inspection under Sect. 91 (3) (a) states that the operation does not need to apply a restraining torque to the motor casing, that the tool may be used for grinding, that centrifugal force may be replaced by springs or gravity, and that the slots 11 may be curved in either direction. This subject-matter does not appear in the Specification as accepted.