Lever escapement "draw" its action is very precise. Third, it is self-starting, so if the watch is jarred in use so the balance wheel stops, it will start again. A cheaper and less accurate version of the lever escapement, called the pin pallet escapement, invented by Georges Frederic Roskopf in 1867, is used in clocks and timers. The escape wheel is geared to the watch's wheel train, which applies torque to it from the mainspring. The rotation of the escape wheel is controlled by the pallets. The escape wheel has specially shaped teeth of either ratchet or club form, which interact with
Anchor escapement it unwinds. An escapement in which changes in drive force do not affect the rate is called isochronous. The superior performance of the deadbeat over the recoil is due to improved isochronism. This is due to the different ways changes in drive force affect the swing of the pendulum in the two escapements: When the deadbeat was invented, clockmakers initially believed it had inferior isochronism to the anchor, because of the greater effect of changes in force on the pendulum's amplitude. Recent analyses point out that the nonisochronism of the anchor can cancel the circular error of the pendulum. That