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The screws in the junk ring are each provided with a small ratchet, cut in a washer fixed upon the head, to prevent the screw from turning back; and the number of clicks given by these ratchets, in tightening up the bolts, enables the engineer to know when they have all been tightened equally. In more recent engines, and especially in those of large size, Messrs.
Seaton, knowing that he was in sole control of the power-plant, fought to retain possession of his faculties, while the hands of the clock told off the interminable minutes. After an eternity of time an hour had passed, and Seaton attempted to cut down his power, only to find with horror that the long strain had so weakened him that he could not reverse the ratchet.
Another way is to take two turns of a rope round a donkey-engine, paying in and coiling while the engine clanks. And another way on smaller boats is a sort of jack arrangement by which you give little jerks to a ratchet and wheel, and at last It looses Its hold.
In most cases the motion is communicated by means of a detent, attached to some reciprocating part of the engine, to a ratchet wheel which gives motion to the other wheels in its slow revolution; but it is preferable to derive the motion from some revolving part of the engine by means of an endless screw, as where the ratchet is used the detent will sometimes fail to carry it round the proper distance.
Local clocks controlled from a standard clock by electricity have been more successful in practice, and are employed in several towns for example, Glasgow. Behind local dials are electromagnets which, by means of an armature working a frame and ratchet wheel, move the hands forward every minute or half-minute as the current is sent from the standard clock.
By a belt from the cam or counter shaft, cause a powerful electric magnet to extract all magnetic particles; then, by a simple ratchet movement, at intervals withdraw the magnet and drop the adhering fragments into a receptacle by automatically switching off the electric current.
Every ferry passenger is familiar with the rapid tinkling of the ratchet wheel that warps the landing stage up to the level of the boat's deck. I asked the man who was running the wheel where I would find the Wenonah. "She lays over in the old Market Street slip," he replied, and cheerfully showed me just where to find her. "Is she still used?" I asked.
The spur-wheel and ratchet, as at present largely used in machinery, offer a rough and ready means of solving this problem, but two very important improvements must be effected before full advantage can be taken of the principle involved.
By the deathless fallacy which credits or blames the ruling powers for everything, natural or supernatural, Shelby's party reaped abundantly where it had sown with niggard hand. The governor's personal deserts were more solid, the public recognizing his retarding ratchet as the cause of the machine's continence and the lowered tax-rate.
He hammered out a lead templet to cover the wound in the boiler, which, of course, as bad luck would have it, was situated at a place where three plates met; and then whilst Balliot's armorer with fire and hammer beat out a plate of iron the exact counterpart of this, he rigged a ratchet drill and bored holes through the boiler's skin to carry the necessary bolts.
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