Riefler escapement

Riefler escapement used in the Clemens Riefler regulator clock, 1893. Shows the bearer (A'), knife edges (c), agate support surfaces (P), suspension spring (i), locking escape wheel (h), impulse escape wheel (H), and pallets (S,S').
The Riefler precision pendulum clock No. 549, currently (2006) serving as the workshop regulator in the horological workshop of the Deutsches Museum.
Side view, closeup of double escape wheel of Riefler No.549. This clock has clear synthetic ruby pallets. (Dial on the right side.)

The Riefler escapement is a mechanical escapement for precision pendulum clocks invented and patented[1] by German instrument maker Sigmund Riefler in 1889.[2] It was used in the astronomical regulator clocks made by his German firm Clemens Riefler from 1890 to 1965,[3] 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, moving the clock hands forward at a steady rate. The Riefler escapement was an improvement of the deadbeat escapement, the previous standard for 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.

  1. ^ German patent no. 50,739
  2. ^ Special Catalog of the Joint Exhibition of German Mechanicians and Opticians, Section 3, Class 15, International Exposition, Paris 1900. Berlin: Reichsdruckerei. 1900. p.36
  3. ^ Day, Lance; Ian McNeil (1996). Biographical Dictionary of the History of Technology. New York: Routledge. ISBN 9780203028292. p.602