Patent GB-191413581-A (GB)
Title: Improvements in or relating to Driving and Stopping Mechanism for Sewing or other Machines.
IPC: D05B69/16
Filed: 1914-06-04
Granted: 1915-06-03
Abstract: 13,581. British United Machinery Co.. [United Shoe Machinery Co.]. June 4. Sewing-machines; stopping-gear, automatic.- A mechanism for use in high-speed sewing or other machines which perform a cycle of operations in a short time and require to be stopped frequently with their parts in a predetermined position comprises separate mechanisms for forward driving at high and low speeds and reverse driving respectively, with automatic mechanism for rendering the low-speed forward and reversing mechanisms successively active when the high-speed mechanism is thrown out by the operator. The low-speed mechanisms act to overcome frictionally the momentum of the driven parts, to continue the forward movement at a slow speed, to reverse the movement at a predetermined point, and finally to bring the part to rest in a predetermined position. The mechanism shown is especially designed for a welting and turnshoe-sewing machine and stops the forward movement after the needle has cast off its loop, and then turns it back to a position in which the needle is retracted and the work can be removed and inserted. The cam shaft of the sewing-machine is driven through a shaft 1, journaled at the lower end in a casing 2 and driven by bevel-wheels 3, 4, Fig. 3, the latter of which has a sleeve 5 and also carries one member 7 of a main driving friction clutch, the other member of which is carried by the freely-mounted driving-pulley 9. The casing 2 is secured upon a sliding rod 10 controlled by a spring 12 and a wedge 13, Fig. 1, which is operated by a starting and stopping treadle 11 to control the main driving-clutch. When this is disengaged, the slow-speed mechanisms come into operation. These comprise two epicyclic gear trains, shown in Fig. 3. in which the planet pinions 17, 18, 19 turning together in the driving-pulley 9, gear with pinions 20, 21, 23 secured respectively to the sleeve 5, brake drum 26, and brake drum 24. The brake drums surround pairs of brake shoes 27, 28 mounted on fixed pivots 29. Fig. 4, and engaging at their free ends the flattened ends 31 of a rock-shaft 32. When this is held in mid-position, as shown in Fig. 4, both pairs of brake shoes are contracted by their springs 33, and the brake drums are free to rotate with the driving-pulley. The means for operating the rock-shaft 32 to put the low-speed mechanisms into action comprise a sleeve 34 on a fixed shaft 35 and having an arm 36 connected by an expansible spring link 37 with an arm 38 on the rock-shaft. By means of a torsional spring, the sleeve tends to rock in the direction of the arrow, Fig. 4. It is normally held by a latch 41, which engages a block 42 on the arm 43 of the sleeve, and is swung out of engagement by a spring link 46, when the sleeve is rocked in an opposite direction to expand the shoes 27. The latch is then held out by a second latch, and the sleeve is free to move in the direction of the arrow beyond the mid-position, under control as described below, to expand the shoes 28. When this movement takes place, the second latch is released, and the latch 41 swings in ready to snap under the block 42 when the sleeve 34 is returned to midposition. The movements of the sleeve are controlled from a cam-groove 54, on the rear face of the clutch member 7, by a lever 50, which is adapted to co-operate with a compound arm 56, 57 of the sleeve. Normally the lever 50 is located on one side of the arm 56, and rides idly against the outer surface of the camgroove, but when the rod 10 and casing 2 move to disengage the main clutch, the lever 50 is also moved laterally, and when further, its bowl comes to a low part 54<a> of the casing, the arm 56 snaps under the lever 50, and the sleeve is then operated by the part 54<b> of the cam to expand the brake shoes 27 and thus gradually to reduce the speed of the machine to that given by the forward-driving differential train. This speed continues until the point 54<c> of the cam is reached, when the bowl moves to the lowest part 54d of the cam, and the sleeve is rocked by the spring to disengage and engage respectively the shoes 27, 28. The machine is then driven at a slow speed in a reverse direction, the bowl of the lever 50 rides up the part 54<e> of the cam, returning the rock-shaft 32 to the mid-position, and disengaging the brake shoes 28, the momentum of the machine bringing the parts to the stop position in which the end 54<f> of the cam-groove is against the bowl. To prevent premature engagement of the lever 50 and arm 56 by an upward movement of the treadle, such as may be required in the normal running of the machine, in order to vary the pressure on the driving-clutch, a pivoted latch 61, Fig. 1, is provided to engage an adjustable screw stop 62, and hold the rod 10 against movement by the spring 12, until the wedge 13 rises sufficiently for a pin thereon to release the latch.