An idler gear, also known as a follower gear, is a type of gear that is used in mechanical systems to transfer power or motion from one gear to another. Some synonyms for idler gear include "auxiliary gear," "intermediate gear," "layshaft," and "jackshaft." Each of these terms refers to a gear that is designed to assist the primary gears in a system without directly transferring power. This can help to ensure that the primary gears are properly aligned and can reduce wear and tear on the system as a whole. Idler gears are commonly used in automotive, industrial, and agricultural applications.