English: Diagram of the chronometer detent escapement. The escape wheel (a) advances by one tooth for each full oscillation of the impulse roller (b), which is attached to the balance wheel (not illustrated). As depicted, the impulse roller is rotating counterclockwise, and the impulse pallet (c) has rotated to a position under an escape wheel tooth, without quite touching it; the escape wheel is held in place by the locking pallet (d), which is held in position by the spring-loaded detent arm (e, f, g, h). This will be released when the discharging pallet (dotted lines under impulse roller) presses against the gold spring (i), which in turn presses on the detent horn (h), retracting the detent blade (g) and the attached locking pallet. The escape wheel rotates freely for a short distance until it contacts the impulse pallet, after which the wheels rotate together, transferring energy from the spring-drive escape wheel to the impulse wheel. Next, the discharging pallet falls off the end of the gold spring, and the detent arm springs back into place. When the impulse pallet rotates so far that it releases the escape wheel, the wheel rotates a small distance further until its next tooth engages the locking pallet. This additional rotation is just enough so that when the impulse wheel rotates back (clockwise), the impulse pallet does not hit either escape wheel tooth. During this portion of the cycle, the locking pallet remains in place; the gold spring acts like a one-way ratchet, being pushed aside by the discharging pallet without moving the detent arm.