Riefler Escapement - How IT Works

How It Works

In the Riefler escapement, the energy required to keep the pendulum swinging is instead supplied by bending the short straight spring strip which suspends the pendulum. The upper end of the suspension spring is not attached to a fixed support as in most clocks, but instead is attached to a heavy metal bearer, which pivots on two aligned knife-edges on its underside which rest on flat agate plates. The bending point of the suspension spring is in alignment with the line of contact of the knife-edges. When the pendulum passes its bottom point, the escape wheel is unlocked and pushes the bearer, and the bearer pivots suddenly on its knife edges by a small angle, flexing the spring. The spring is bent by a small amount in addition to that caused by the swing of the pendulum, and thus provides the impulse for the next swing. So the suspension spring is used for two functions: suspending the pendulum and giving it impulse.

The escapement has better performance than the deadbeat because the force from the pallets, with its variability, is applied not to the pendulum but to the bearer. The escapement has no contact with the pendulum below the suspension spring. The pendulum is free of disturbance from the escape wheel for most of each swing and the only work it has to do is to unlock the escape wheel once per second. This operation is performed near the ideal place, at the center of each swing.

The Riefler escape wheel and pallets are of a special design. There are actually two escape wheels mounted on the same shaft and two surfaces on each of the two pallet pins. The front locking wheel has forward pointing teeth rather like a dead-beat escapement, and catches on the flat surface of the pallet to lock the wheel. The rear impulse wheel has teeth with a sloping surface facing the direction of rotation. The round part of each pallet is acted upon by this surface to give the impulse.