The mechanism that converts the energy from the clocks rotation to lateral impulses is called the escapement. It is easier to define it based on the tick tock sound you hear. The escapement is the source of the tick-tock sound as a result of the locking and unlocking of the pallet fork. When the pallet fork locks and unlocks in the escape wheel, the balance wheel vibrates.
To better understand the concept f the escapement, imagine a watch without this part. After it wounds, you cannot control the unwinding. Unwinding will be in an uncontrollable manner that the movement will not be balanced. Since the escapement is responsible for releasing the power from the mainspring, the movement of the balance wheel and the hairspring will be regulated.
In horology, the development of the escapement whether in the technical and historical mediums, is very fascinating. Through the years, many types of escapements have been created but not all have survived due t efficiency and effectiveness reasons. Currently, what is found to be most practical in the watch-making industry is the lever escapement.