Lot 76

Edward John Dent

Clockmaker to the Queen

A London long case precision regulator with Denison's four legged cravity escapement

Sold

Edward Denison (later Lord Grimthorp) perfected the gravity escapement in 1860 by eliminating the tripping problem. He did this through the connection of a fly, a.k.a. an air brake, directly to the escape arbor via a friction clutch. It allows the fan to advance slightly after the escapement engages the pallet. The inertia provided by the weight of the fly keeps the escapement seated against the pallet during locking; in essence acting as an 'energy sink'. This escapement provides a nearly detached pendulum from the rest of the clockwork and is particularly important in tower clocks where wind and weather can cause disruptions to the movement through the exterior hands. Another special feature of this escapement is that there is no sliding friction so it does not need oil on the escapement. Again, due to the environment in which tower clocks are found oil contamination is a problem; severe temperature changes can cause oil to thicken and thin beyond their normal intended characteristics. Because of these features afforded by the gravity escapement, the use of a train remontoire is rarely seen in conjunction with it. While there was some improvement in accuracy over the deadbeat escapement, its real virtues lie in its stability, the design’s ability to keep the pendulum largely detached from the rest of the train, and the lack of need for oil.
Source: https://www.my-time-machines.net/escapement_remontoire.htm