Stud escapement, used in large clocks
Stud escapement, used in large clocks. One pallet, B, works in front of the wheel and the other at the back. The studs are arranged in the same manner, and rest alternately upon the front or back pallet. As the curve of the pallets is an arc described from F, this is a repose or dead-beat escapement.
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
- The escape-wheel carries 24 studs on its front face and 24 on its back, at radius 8 cm, the back ones half way between the front ones. The pallets' arbor F stands 10 cm up the tangent from the point where the pallets work, 25° up the wheel's right side, so the pallets go in and out across the studs' circle as the arbor rocks. B, in front, comes in from outside and catches the front studs. A, at the back, comes in from inside and catches the back studs. Each pallet's upper face is its locking face, an arc about F (Brown's dead-beat curve), so a stud resting on it is not moved as the pallet slides under it. The pallet's corner nearest the studs' circle is bevelled. When the pallet has slid out far enough, the stud comes down the bevel and pushes it on out (the impulse), drops off, and the next stud of the other face falls on the other pallet, now in. The only input is a constant torque on the wheel (the weight). The pendulum hangs from F behind the wheel and is kept going only by the studs.
- Measured
- It starts itself from rest. The wheel goes 0.1309 rad per beat (half a stud's pitch, 0.1309) over 14 beats. The swing holds at 5.8°. The wheel never turns back more than 0.0026 rad (the stud's bounce as it drops on a locking face): the rest is dead. The period is 0.888 s, 1.8% slower than the pendulum swinging free (0.873 s). The deepest contact is 0.17 mm.
- Notes
- Brown gives no sizes. The stud count, the 25° working point and the bevels are choices. The arc of each locking face is built from six short straight pieces. The pendulum is drawn behind the wheel; Brown shows only the pallets and their arbor F.
Film (MP4) · Still (PNG) · Spec (YAML) · Model (MJCF)
