Harrison's Going-Ratchet

“The click barrel-ratchet R is set upon another larger ratchet-wheel, with its teeth pointing the opposite way, and its click rT is set in the clock-frame. That ratchet is connected with the great wheel by a spring ss’ pressing against the two pins s in the ratchet and s’ in the wheel. When you wind up the weight, the click Tr prevents the ratchet from turning back or to the right; and as the spring ss’ is kept by the weight in a state of tension equivalent to the weight itself it will drive the wheel to the left for a short distance, when its end s is held fast, with the same force as if that end was pulled forward by the weight; and as the great wheel has to move very little during the short time the clock is winding, the spring will keep the clock going long enough.” — Encyclopedia Britanica, 1893

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