Single Pin Escapement
W. H. SAMELIUS
The most common pendulum escapement used today was invented by Dr. Hooke. of England, 1675; it was known as the anchor recoil. We find this style of escapement in most of our mantle and kitchen clocks especially where a short pendulum is employed. It has proven to be practical, easy to adjust and lends itself to production in large quantities.
Another escapement that has stood the test of time and accepted, is the deadbeat escapement, invented by George Graham of England during the early part of the 18th century. The deadbeat escapement is employed for long pendulums, such as second's beat regulators, in fact, many of our most accurate timepieces today are equipped with a Graham Dead-Beat.
Another escapement that has proven it's practicability, especially for tower clocks, is the gravity escapement, invented by Dennison of England, 1854. He designed and caused to be constructed, the Tower Clock in Westminster Tower, London, called "Big Ben." For this achievement, Dennison was awarded a Lordship (Lord Grimthrope).
There is still one more· escapement that is to be found in Observatory clocks. Namely, the "Rieffler Clock and Rieffler Escapement." Generally speaking, most all observatories throughout the world use the deadbeat escapement or the Rieffler escapement.
Among the discontinued escapements we find a very simple one, perhaps the simplest of all, known as the Single Pin, invented by Charles McDowell of Wakefield, England, He was a clever horologist making many outstanding masterpieces, many refinements and modifications in clock constructions, also inventing the single pin escapement. He died in 1872 at the age of 82. The accompanying illustration shows his method of maintaining a pendulum in motion.
The escapement consisted of a roller attached to the projecting pivot or the escape wheel pinion, an impulse pin being fastened into the roller. The impulse pin and roller rotated anti-clockwise. Impulse was imparted to the vertical section of the upper pallet, the pin would then drop off to the horizontal section of the lower pallet. On return of the pendulum, the pin would slide through the space between the two pallets, returning, giving impulse to the vertical face of the lower pallet, the pendulum being pivoted. The weight of pendulum bob would naturally cause considerable wear and friction on the upper support, detrimental to the life of the clock and another objection was the escape pinion would make one complete revolution for each two impulses, necessitating a greater number of wheels and pinions in the train, this also was objectionable and did not prove practical for production and was finally abandoned.