Screw mechanism
Lead and pitch

The fineness or coarseness of a screw's threads are defined by two closely related quantities:

In most screws, called " single start " screws, which have a single helical thread wrapped around them, the lead and pitch are equal. They only differ in " multiple start " screws, which have several intertwined threads. In these screws the lead is equal to the pitch multiplied by the number of starts. Multiple-start screws are used when a large linear motion for a given rotation is desired, for example in screw caps on bottles, and ball point pens.
change_case:english_lowercase