GB797226A - Improvements in or relating to marking heads - Google Patents

Abstract

797,226. Number printing apparatus; selective printing. PRYOR & SON, Ltd., E. Aug. 23, 1956 [Oct. 26, 1955], No. 30571/55. Classes 100(2) and 100(4) In a marking head 1 of the type having a plurality of character wheels 3 capable of selective or automatic rotation to bring any desired combination of characters 15 into line for simultaneous impression each of the rotatable character wheels 3 has a ratchet 6 for engagement with a locating pawl 13, the pawls 13 being pivoted to the body of the head 1 by relative engagement of each pawl 13 and the head 1 through a V-groove 7 transverse to the length of the pawl and formed in apart 8 attached to the head 1, and a rounded lateral projection 14 formed on each pawl 13 and fitting the sides of the groove together with a spring to urge the projection and the groove into mutual contact. Alternatively the V-groove may be formed on each pawl and the projection on the part 8, (Fig. 3, not shown). As shown in Figs. 1 and 2 the spring each consist of a spring wire 16 extending from a hole 19 in an anchorage 17 on the head 1 so that the free end of the wire 16 bears on a rounded portion 22 in a groove 20 formed in the corresponding pawl 13. The other end of each pawl 13 is provided with a portion 12 for engagement with teeth 11 in the corresponding ratchet wheel 16, which together with its associated character wheel 3 is rotatably mounted on a fixed shaft 4. The portion 12 of each pawl 13 is held in position by a second wire spring 23 also fixed to the anchorage 17. An operating lever 25 may be provided which carries a multiple-toothed pawl 28 adapted to engage the teeth 11 of the wheel 3, a spring- urged bar 29 projecting from the lever 25 for operation at each stroke of the head. In alternative arrangements the pawls may be held in position by spring wires extending upwardly and downwardly from an anchorage located intermediate the end of the pawls (Fig. 4, not shown), by spring wires mounted on a transverse cylindrical bar and having ends bearing on the head 1 and pawls 13 respectively. (Fig. 5, not shown), by compression springs having ends located in pockets in the pawls and in pockets in bridge pieces attached to the head respectively (Fig. 7, not shown) or by a combination of compression springs for one end of the pawls and wire springs for the other ends of the pawls (Figs. 8 and 9, not shown).