GB947200A - Improvements in electrically driven sewing machines - Google Patents

Abstract

947,200. Controlling clutches &c. LIGHT'S LONDON Ltd. Sept. 26, 1962 [Oct. 19, 1961], No. 37572/61. Heading F2L. [Also in Division D1] A pulley 25, journalled on the shaft 3 of an electric motor 2, is coupled by a belt 27 to a pulley 28 fixed to the arm shaft 6 of a sewing machine. A driven clutch element 35, splined to a boss 33 of pulley 25, is engaged with a driving clutch element 36, fired to shaft 3, upon energization of a clutch coil 38. A first brake element 50, splined to a boss 51 of pulley 28, is engaged with a shroud and fired brake element 56 upon energization of a brake coil 55. A cam 60, fired to shaft 6, co-operates with a pivoted follower 16 spring-biased thereagainst, to permit closure of contacts 64 and 65 when follower 61 engages a flat surface on cam 60. The presser bar 13 carries a lateral bar 75 which, when the presser bar is raised by a lever 19' permits a contact arm 76 of a micro-switch 74 to engage a contact 77, and when the presser bar is lowered moves arm 76 into engagement with a contact 78 of switch 74. A tapping from a field winding 70 of the induction motor 2 is connected to the input of a rectifier 73, to the output of which is connected the clutch coil 38 in series with the contact arm 76 and contact 78. Two parallel circuits, containing respectively a lamp 80 fixed on the machine arm 5 and the brake coil 55 connected in series with the contacts 64, 65, are connected across the output of rectifier in series with the contact arm 76 and contact 77. The arrangement is thereby such that when the presser bar is lowered, clutch coil 38 is energized to drive the machine, and when the presser bar is raised, lamp 80 is lit and the machine continues to run until contacts 64, 65 close to energize the brake coil 55, when the machine stops with the needle raised. The contacts 77, 78 are shunted by a circuit containing a variable resistor 81 mounted on the arm 5, and a micro-switch 84 which is mounted above switch 74 and has a contact arm 82 moved momentarily into engagement with a contact 78 when the lever 19 is lifted fully. The latter operation is performed if the needle does not initially stop in the fully raised position, and has the effect of momentarily re-energizing coil 38 via resistor 81 to drive the machine slowly until the contacts 64, 65 close. Resistor 81 is so adjusted as to ensure slipping of the clutch if coil 38 is energized when the contacts 64, 65 close. Specification 923,389 is referred to.