Escape wheel

The escape wheel is the wheel the escapement acts on. Driven by the gear train, it is held still by one pallet of the pallet fork, released, and caught again by the other, so that the train advances one tooth at a time and the balance receives one push per release. The shape of the teeth defines the variety of escapement: the Seiko Museum Ginza describes the earliest lever form as a ratchet tooth design whose "pointed teeth" "would push against the pallet stones of the anchor", later replaced by the club tooth escapement with teeth "resembling golf clubs" that "absorb the impulse of the escape wheel with the flat surface", reducing wear.

The contact between tooth and pallet is where a mechanical watch loses most of its energy to friction, and it is the part of the movement that depends most on oil. George Daniels' patent application makes that the whole point of his design: "The invention relates to a detached escapement which preferably does not require oil to be applied to the escape wheel."

Materials have changed. The Seiko Museum Ginza states that "An increasing number of manufacturers are using silicon materials not only for the hairspring, but also for the escape wheel and pallet fork", because "Silicon has a smooth surface and is both hard and light, which means that it can reduce accuracy errors caused by friction while also reducing the frequency of oiling." Speaking for its own company, the museum adds: "Although silicon is hard, it is brittle under impact, and for this reason Seiko does not use it." Seiko instead "manufactures its escape wheels and pallet forks from nickel alloys using MEMS (Micro Electrical Mechanical Systems)," the museum's own account of its company's practice.