Riefler Escapement

The Riefler escapement is a mechanical escapement for precision pendulum clocks invented and patented by German instrument maker Sigmund Riefler in 1889. It was used in the astronomical regulator clocks made by his German firm Clemens Riefler from 1890 to 1965, which were perhaps the most accurate all-mechanical pendulum clocks made.

An escapement is the mechanism in a mechanical clock that gives the pendulum precise impulses to keep it swinging, and allows the gear train to advance a set amount with each pendulum swing. The Riefler escapement was an improvement of the deadbeat escapement, the standard used in precision clocks. In the deadbeat, the force to keep the pendulum swinging is applied by the teeth of the escape wheel sliding alternately against two angled pallets on arms attached to the pendulum. Therefore, slight variations in the friction of the pallets and in the torque from the escape wheel are passed on to the pendulum, disturbing its motion.