Pawl.
A pivoted bar adapted to fall into the notches or teeth of a wheel as it rotates in one direction, and to restrain it from back motion.
Used in windlasses, capstans, and similar machinery.
The pawl acts by gravitation or by a spring.
The same device is called a
click when acting in connection with a ratchet-wheel, as in the winding part of a watch.
It is sometimes called a
detent. This is its office, but the thing has already names enough.
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Pawl in hoisting-apparatus. |
Figs. 3578,
3579,
3580, show three applications of the pawl, and many others may be found incidentally shown in connection with devices, such as
click, ratchet, etc.
Fig. 3578 is a hoisting lever having a pair of pawls acting upon a ratchet on the shaft of a windlass.
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Pawl in harvester-wheel. |
Fig. 3579 shows the pawl and ratchet gear of the driving apparatus of a harvester.
As the machine moves in a curve, one of the propelling wheels will revolve faster than the other, and the link which connects the pawl with the frictionband is silently disengaged from the teeth of the case on the outer curve.
When the machine turns a curve in the opposite direction, the pawl is made to engage with the teeth.
[
1643]
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Pawl on wagon-lock. |
Fig. 3580 shows the application of a click and ratchet holding-device for a wagon-lock.
A handle, which is secured to the pawl, extends upward and slides in a guard attached to the brakelever.
It is used to release the pawl from the ratchet.
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Feed-motion of Colt's pistol. |
The mode of rotating the barrel of the Colt pistol is by means of a pawl pivoted to the lower part of the hammer, and acting upon a crown ratchet on the rear of the barrel.
As the hammer is brought to the cock, the pawl
a rises, being kept to its work by a spring
c, which forces it into the interdental spaces of the ratchet.
As the hammer falls, the pawl slips and takes hold of the next ratchet-tooth.
