Anchor escapement the tooth sliding along its surface, pushing it. Then the tooth slides off the end of the pallet, beginning the cycle again. Neither the anchor escapement nor the deadbeat form, below, are self-starting. The pendulum must be given a swing to get them going. The backward motion of the escape wheel during part of the cycle, called "recoil", is one of the disadvantages of the anchor escapement. It results in a temporary reversal of the entire wheel train back to the driving weight with each tick of the clock, causing extra wear in the wheel train, excessive wear to the
Escapement was unworkable. Arnold also designed a spring detent escapement but, with improved design, Earnshaw's version eventually prevailed as the basic idea underwent several minor modifications during the last decade of the 18th century. The final form appeared around 1800, and this design was used until mechanical chronometers became obsolete in the 1970s. The detent is a detached escapement; it allows the balance wheel to swing undisturbed during most of its cycle, except the brief impulse period, which is only given once per cycle (every other swing). Because the driving escape wheel tooth moves almost parallel to the pallet, the escapement