GB352469A - Improvements in or relating to impulse transmitters for use in telephone or like systems - Google Patents

Abstract

352,469. Impulse transmitters. AUTOMATIC TELEPHONE MANUFACTURING CO., Ltd., Strowger Works, and SMITH, S. R., Rock House, Old Swan, both in Liverpool. April 8, 1930, No. 11206. Addition to 234,036, [Class 40 (iv), Telephones &c.]. [Class 40 (iv).] In the impulse transmitter described in the parent Specification wherein the mechanism is mounted in a cylindrical casing having a flat back, the shape of the casing is modified to facilitate mounting in a circular recess of smaller diameter than the normal diameter of the dial. Moreover, the member which moves the impulse springs out of range of the impulse cam at the end of impulsing, is modified in order that two or more operations of the cam may be rendered ineffective. As shown, the base of the dial switch has a cylindrical portion 4 eccentric with respect to a ledge 3 on which the finger stop plate 7 is mounted, the stop plate comprising projections 15, 6, 19 which respectively form a bearing for the shaft 14 of the impulse cam, a stop for arresting the moving parts of the dial switch when restored to normal and a stop for engaging the projection 21 of the driving pawl. The. driving gear, and the impulsing equipment are arranged as described in the parent Specification. The numeral plate is secured in position by a spring 23 which is secured in the centre of the dial by a radial limb and has limbs 24, 25 provided with upturned portions 42, 43 for engaging the number plate at diametrically opposite points. A single stamping 26 carries the off-normal and impulsing springs and has two limbs 28, 29 provided with pins for engaging holes in the walls of a recessed support, e.g. a recess in a telephone instrument. The transmitter may then be secured by a single screw which passes through the hole 31. Alternatively the dial switch may be supported by screws passing through holes 50, 51 in the ledge 3. By arranging the cylindrical portion, 4 of the base eccentric with respect to the ledge 3, impulsing and off-normal springs of greater length may be employed. The cam-shaped arm 39, Fig. 3, is lengthened in comparison with that shown in the parent Specification and additional teeth are provided on the wheel 12 in order that the impulse springs may be rendered ineffective for an additional number of half revolutions of the impulse cam. The size of the fingerholes for a given diameter of fingerplate is also reduced. Specifications 226,152, 237,290, and 252,674, [all in Class 40 (iv), Telephones &c.], are referred to.