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RATCHET MECHANISM OF A CHRONOMETRIC TACHOMETER

A chronometric tachometer, which measures the rpm of a shaft during three seconds, incorporates an element of clockwork. When a button (not shown) is pressed, ratchet wheel 1 begins to rotate. Its speed is controlled by balance wheel 2 and double-ended pawl 3. Cam 4, keyed to the shaft of wheel 1, turns through a certain angle and then releases latch 5 for exactly three seconds. As a result, ratch…