The former is what is termed a recoil, and the latter a repose or…
288 and 289. The former is what is termed a recoil, and the latter a repose or deadbeat escapement for clocks. The same letters of reference indicate like parts in both. The anchor, H, L, K, is caused, by the oscillation of the pendulum, to vibrate upon the axis, a. Between the two extremities, or pallets, H, K, is placed the escape-wheel, A, the teeth of which come alternately against the outer surface of the pallet, K, and inner surface of pallet, H. In 289 these surfaces are cut to a curve concentric to the axis, a; consequently, during the time one of the teeth is against the pallet the wheel remains perfectly at rest. Hence the name repose or dead-beat. In 288 the surfaces are of a different form, not necessary to explain, as it can be understood that any form not concentric with the axis, a, must produce a slight recoil of the wheel during the escape of the tooth, and hence the term recoil escapement. On the pallets leaving teeth, at each oscillation of the pendulum, the extremities of teeth slide along the surfaces, c, e, and d, b, and give sufficient impulse to pendulum.
Only the input is driven; every other part of this model moves by physics (MuJoCo), and its ratios are measured. Run it live, change its parameters, or switch the friction off to see the output stop.
- Modelled as
- This is No. 303's 30-tooth wheel and anchor, mirrored so the escape-wheel A turns counter-clockwise, with Brown's letters. K (right) is the pallet whose outer face the teeth meet; H (left) is the one whose inner face they meet. Neither locking face is an arc about the axis a: going on from the impulse corner, each reaches 1.2 cm of radius per radian further into the wheel's path. The only input is a constant torque on A (the clock's weight). The anchor and pendulum swing under gravity and are kept going only by the teeth pressing on the pallets.
- Measured
- A advances 0.1048 rad per beat (half a tooth, 0.1047). While a tooth is locked, the wheel turns back by up to 0.0139 rad (0.80°) every beat and then forward again. No. 289's concentric faces give 0.0016 rad. The swing holds at 5.6°. The period is 0.843 s, 4% quicker than the free compound pendulum's 0.882 s, because the recoil faces push the pendulum back on each supplementary arc.
- Notes
- Brown says the recoil faces' form is not necessary to explain. Here they are straight-run spirals about a, a choice. Brown's letters c, e and d, b for the impulse faces are not drawn.
Film (MP4) · Still (PNG) · Spec (YAML) · Model (MJCF)
