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
Mechanical energy isolated system remains constant in time, as long as the system is free of friction and other non-conservative forces. In any real situation, frictional forces and other non-conservative forces are present, but in many cases their effects on the system are so small that the principle of conservation of mechanical energy can be used as a fair approximation. Though energy cannot be created or destroyed in an isolated system, it can be converted to another form of energy. In a mechanical system like a swinging pendulum subjected to the conservative gravitational force where frictional forces like air drag and friction