Drop
Is the amount of freedom allowed, in parts which come in contact with each other, to compensate for inaccuracies in workmanship. In horology it is principally applied to the escapement action where a tooth of the escape wheel drops a varying distance from the completion of one action to the beginning of another. In the chronometer, and other escapements, there are two drops. One drop begins at the completion of the unlocking, when the tooth falls upon the impulse pallet, and the other one begins at the completion of the impulse and ends when the tooth drops upon the locking stone. In the lever and cylinder escapements the drop is known as inside or outside drop, according as it takes place on the inside or outside of the pallet or cylinder. All drop is just so much power wasted and should be as small as possible.