GB699647A - Improvements in and relating to stopping mechanism for sewing and other machines - Google Patents

Abstract

699,647. Sewing-machines. REHER, L. J. M. Feb. 14, 1951 [Feb. 17, 1950], No. 3606/51. Class 112. [Also in Group XXXIV] Driving; stopping.-A preferably electricallyoperated brake for retarding the movement of the machine, the brake being adapted to rotate with the braked part of the machine, is operatively connected with an electrically-operated slow-speed driving gear in such a way that after synchronisation of the brake and the machine consequent on the braking action the machine is rotated at a reduced speed to a predetermined position in which an operating circuit of the slow-speed gear or of the brake, or both, is interrupted by a member moving with the machine. In the arrangement shown, a disc 1 rotating with the machine forms one element of an electromagnetic clutch of which the other element 4 is mounted on the shaft 6 of a slowspeed motor 7 in such a way that it can slide into contact with the disc 1 and has lost motion to the extent of about 45 degrees relative to the shaft; a spring 18 connects a rod 15 on the member 4 to an arm 17 on the shaft to urge the member to its most advanced position on the shaft. A disc 10 slidably connected to the shaft 6 by a pin 13 and inclined slot 12 and to the member 4 by rods 15 carries ring contacts 20 for supplying the windings of the electromagnet in the member 4 and actuates a sliding switch member 23. When the treadle 29 controlling the machine is allowed to rise and open the circuit of the main driving motor (not shown) it first closes a switch 28 and then allows this switch to reopen. The switch 28 closes a circuit by way of conductors 33, 27 and contact 26 to the switch member 23, and thence to the motor 7 and by contacts 22 to the electromagnet of the clutch element 4; this element is thus drawn into engagement with the disc 1, and a cam ring 39 on the element 4 lifts a contact 31 into engagement with a contact 30 on the member 23 to close a circuit to that member independently of the switch 28 to maintain the motor 7 and electromagnet energised when the treadle 29 is fully released. The machine will now be slowed down to the speed of the shaft 6, by friction between the members 1, 4, and these members will then tend to lag behind the shaft owing to the load imposed by the machine, now being driven by the shaft; this lag, permitted by the lost-motion device in the drive of the member 4, causes movement of the disc 10 to the left by reason of the pin-and-slot connection 12, 13, carying the switch member 23 with it so that the end of the contact member 30 is brought into the path of a projection 3 on the disc 1 and the switch 30, 31 is opened by this projection to stop the machine in a predetermined position and de-energise the clutch electromagnet so that the parts are restored to their initial positions by the spring 18.