GB639118A - Improvements in and relating to driving apparatus for straight bar knitting machines - Google Patents

Abstract

639,118. Knitting. LANCASHIRE DYNAMO & CRYPTO, Ltd., NEVELIN ELECTRIC CO., Ltd., COTTON, Ltd., W., COWLEY, F. T., and LYNAN, J. E. March 14, 1946, No. 7932. [Class 74 (ii)] [Also in Group XXXVII] In or for a straight bar knitting-machine, driving apparatus, of the kind comprising a direct current electric motor having field control and supplied by a mercury arc rectifier with controllable grid bias, is combined with a manually operable phase shifter to control the grid bias and with both manually operable and pattern-controlled means for varying the motor field. When control-rod 9 is in the extreme left-hand position the machine is stationary. Initial movement of the rod to the right closes switch 8, which operates a relay 7 to close the main D.C. contactor 6. Further movement to the right moves a phase-shifter 12, to alter the grid bias to give full armature volts; and the motor runs at a predetermined speed. Continued movement of rod 9 moves an arm 10a, to insert a regulator 10 in the circuit of the motor shunt field winding 2, so that the motor now runs at full, normal knitting speed. To lower the speed for fashioning or for plating, a suitable patterning or timing device closes a switch 13a or 17a, to short an appropriate portion of the regulator and close, for a while, a switch 13b or 17b, controlling a relay 14 which disconnects the armature by opening a switch 15a and places a braking resistance 16 across it by closing a switch 15b. An extremely slow speed, for welt turning or carrier changing, is obtained by closing switches 18a, 18b by a suitable timing or patterning device. The switch 18a remains closed for only a short period and operates the braking relay 14. Switch 18b operates a relay 19, which shifts a contactor 5 to change the tappings on the transformer secondary 4, reducing the voltage to the anodes 3a; and, simultaneously, a contactor 5a shorts out the shunt regulator 10. The patterning mechanism may be set to effect this change to the extremely low speed immediately before the machine stops.