GB864745A - Two-speed drive for sewing machines - Google Patents

Abstract

864,745. Sewing machines. SINGER MANUFACTURING CO. Oct. 6, 1959 [Oct. 20, 1958], No. 33820/59. Class 112 [Also in Group XXIV]. In a sewing machine a two-speed planetary gear mounted on a main driving shaft comprises a plurality of planets mounted on a carrier member and disposed between co-axial planet-engaging surfaces provided on a driving member and reaction member respectively, the planet surfaces being of rubber or like resilient material, and the planets being dimensioned relatively to said planet-engaging surfaces for deforming said resilient material slightly at each point of contact. Three planet wheels 13 are journalled on spindles 14 mounted on a planet carrier member 7 having a hub in the form of a sleeve 8 journalled on a sleeve 5 which is fixed by a screw 6 to the outer end of the arm shaft 3. The planet wheels have rubber tyres 18 which engage outwardly with a corrugated circular surface 22 provided on a reaction member 19 journalled on the enlarged inner end of sleeve 8. The tyres 18 engage inwardly with a corrugated surface 29 formed circumferentially on a sleeve 26 which is journalled on sleeve 8 and constitutes the hub of a handwheel 23 provided with a groove 30 for a driving belt 31. The arrangement is such that the tyres 18 are slightly compressed by the surfaces 22 and 29. A block 32 fixed in the outer end of sleeve 5 journals a spindle 33, to the outer end of which is fixed a hand knob 38. A cam 35 on spindle 33 is formed with two outwardly facing crests 36 separated by two troughs 37. A clutch disc 43, slidably mounted on cam 35, has outwardly extending radial arms 44 which lie in aligned slots 41, 42 formed in the respective ends of sleeves 5 and 8, slots 41 extending further outwardly than slots 42. Clutch disc 43 also has a pair of inwardly extending radial arms 46, and is biased inwardly by a spring washer 48 having radial arms which bear against the arms 44. Knob 38 may be turned to position arms 46 in the troughs 37, when arms 44 will enter slots 42 to couple the planet carrier 7 to the shaft 3. Knob 38 may also be turned to position arms 46 on the crests 36, when the latter will be held in grooves 47 formed in arms 46, and arms 44 will be withdrawn from slots 42 to uncouple planet carrier 7 from shaft 3. A control member 49 is carried by studs 53 slidably mounted in the reaction member 19. Springs 54 bias member 49 to engage radial lugs 51 thereon with radial slots 52 in the handwheel 23, which is thereby coupled to the reaction member 19. The handwheel, the reaction member and the planet carrier will then rotate as a unit, and if the planet carrier is coupled to shaft 3, the latter will rotate at high speed. A lever 58, pivoted intermediately on a fixed lug 59, has its lower end biased by a spring 68 towards a rotary spindle 66 provided with a short radial pin 64 and a long radial pin 65. When spindle 66 is turned by a handle 67 to engage the long pin 65 with lever 58, protuberances 62 on a pair of resilient upper arms of lever 58 engage outwardlyextending, spaced radial lugs 57 provided on the control member 49, whereby the latter is moved against springs 54 to withdraw lugs 51 from slots 52. The protuberances 62 finally engage between the lugs 57 to hold the reaction member 19 stationary. The planet wheels 13 then rotate about their axes and the tyres 18 roll over the surface 22, whereby the planet carrier rotates at a reduced speed, which may be transmitted to shaft 3 by coupling the latter to the planet carrier via knot 38. If spindle 66 is turned to engage the short pin 64 with lever 58, the protuberances 62 move away from the lugs 57 and lugs 51 re-engage slots 52.