Stop-motion.
An arrangement in a machine by which the breakage of material in transitu, or the failure of supply of the material under treatment, causes an arrest of the motion.
Such, for instance, is the attachment in power-looms and knitting-machines.
designed instantly to arrest the movement, if at any time the spool become exhausted in the shuttle, or the yarn happen to break A delicate metallic finger feels for the yarn at the very instant the shuttle completes its course.
If the yarn is in its place it rests there, and the work goes on; if not, it makes an electric contact, and the power is paralyzed in an instant.
In pattern work the advantage of such an attachment will easily be understood.
No time is lost in studying to find where the pattern began to be interrupted, and no trouble is necessary to set backward the Jacquard guides.
Fig 5894 is a stop-motion for warps of looms.
It has a series of pivoted wings
K K from which warpsup-porting rods or threads are suspended.
So long as the warpsupporting rods or threads are kept tense by the warp-thread, they hold the wings in such a position that the same do not
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Warp-thread stop-motion for looms. |
interfere with the motion of a rising and falling flat board; but as soon as a warp-thread breaks, it will cause the release of a warp-supporting rod or cord, whereupon the wing from which the same is suspended will swing upon its pivot, so as to arrest the downward motion of the flat board.
The stopping of the flat board causes a vertically moving shaft to oscillate and thus impart motion to a lever, which, by means of cords, a sliding-frame, a stop and bell-crank lever, is connected with a sliding-rod which operates the belt-shifting lever.
As soon as the rod is released by the withdrawal of the stop, it is moved by the action of a spring, so as to shift the belt to a loose pulley and thus stop the loom, the batten being simultaneously arrested by a stop on said rod.
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Weft-thread stop-motion for looms. |
Fig. 5895 shows a set of devices designed to stop the loom when the weft-thread breaks or gives out; in this case the bars of the grid on the lay are allowed to pass the weft-fork, and a lever is thus allowed to drop so low as to be struck by the wiper
K. which pushes it and the bar forward until the shoulder strikes a lever, and by the intervention of another lever unlocks the shipper.
Stop-motions are also used in
roving, spinning, and
working machinery. See
Fig. 5900. The stop-motion of
drawing-machines is contrived to arrest the motion of the machine when a sliver breaks.
This is accomplished by causing the slivers from the finishing cardingengine to pass over weighted guide-levers, termed
spoons, mounted so as to be capable of turning upon centers, and kept in a certain position by the tension of the fibers while being drawn.
Should one of the slivers break, or a can become empty, the spoon falls, and a part projecting from its under side intercepts the motion of a vibrating bar, and this acts upon other apparatus which shifts the driving strap from the fast to the loose pulley.
See stopping mechanism.
The electric stop-motion for fabric-machines is so arranged that, on the breaking of a single thread, the emptying of a bobbin, the accidental bending of a needle, or on holes being caused in the work by the knotting or thinning out of a thread, an electric circuit is completed, which, passing through an electro-magnet, causes it to attract an armature, and so releases a lever, which, actuated by a strong spring, withdraws a clutch through which motion is communicated to the loom, and the machine is instantly stopped
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Stop-motion for engine. |
Fig. 5896 is a stop-motion for
steam-engines, to come into action automatically in case of the failure or breakage of the governor.
Combined with the governor is a coupling-sleeve with a dog let in crosswise of the same, and a supporting-spring and button in such a manner that when the engine runs at its regular speed and the balls occupy their normal position, the connection between the valve and governor-rod is not disturbed, and the valve remains open; but if from any cause the balls drop down, the dog will strike the button so that it is thrown back, and the sleeve is liberated from the rod of the governor, allowing the same to follow the action of the spring and close the valve, and thus stop the motion of the engine.
