Deadbeat. In the deadbeat escapement, excess power on the regulator and momentum suspend the motion of the escape wheel.

Instead of listing the various deadbeat escapements, I shall speak only of the cylinder type for watches, and the anchor type for clocks.

In the former, we know, the arbor of the escape wheel is parallel to the arbor of the regulator, and the wheel imparts vibrations to the cylinder, which is simply a hollow tube cut away to the center; the teeth of the escape wheel act in alternation on the edges of the cut, with inclined planes on the circumference of the wheel that act on the cylinder edges from the outside in and from the inside out, imparting impulse arcs proportional to the angle of the planes.

Let us assume that one tooth of the wheel pushes on the first edge of the cylinder from the outside and imparts to it the impulse arc; then the tooth leaves the edge and drops onto the concave surface. At this point the balance, which has gained motion, prolongs the arc by five or six times, thereby suspending the motion of the escape wheel; but since it retains a relative motion, considering the circular location of the tooth in the concavity of the cylinder, this is one of the deadbeats of this escapement. When the vibration is completed, the reaction of the spiral spring returns the balance, and the tooth traverses the same circular space in the opposite direction, still with relative motion, and in an absolute deadbeat , until the tooth reaches the second edge of the cylinder. Then resuming its own motion, it imparts an impulse arc from the inside out, then it leaves this edge, and the next tooth drops onto the convex circumference, making the other deadbeat of this escapement. At this point, the balance continues its arc five or six times further, and the tooth traverses a circular space on the convex surface, as it did previously on the concave surface.

The property of suspending the motion of the escape wheel leads most horologists to think that the regulator completes its vibration in complete freedom, thereby compensating perfectly for inequality in the power. On examination, we see that this is not true, for the freedom of the vibration is hindered by the friction of the tooth on the outer and inner diameters of the cylinder; that is why in this escapement the regulator is less powerful than in a recoil escapement.

Another deadbeat escapement, called the virgule escapement , has an advantage over the cylinder, especially since I made the deadbeat radii as short as possible and thus made the vibration freer, thereby making the regulator more powerful. The Académie des Sciences has appproved both the escapement and its application. See Escapement.

In the deadbeat anchor escapement for clocks, the vibrations alternate as in recoil escapements, except that to reach a deadbeat , the wheel teeth need not encounter the inside or outside of the anchor arms, but circular locking faces concentric with the center of motion, remaining at rest there while the anchor describes its arc and completes its oscillation.

As in all deadbeat escapements, there is two-way friction, therefore oil is required to ease the motion; thus, far from allowing complete freedom of vibration, the deadbeat is the very factor that hinders it.