What is backlash in a gear mechanism?

Backlash in a gear mechanism refers to the amount of play or clearance between engaged gear teeth. This occurs when the gears are meshed, and there is a slight gap that allows the gears to move without immediately transferring motion. This space can lead to positional errors because, when one gear drives another, the slight movement required to close the gap means that there can be a delay or a difference in the positioning of the gears.

In precision applications or systems requiring accurate control, backlash can be problematic as it can lead to inaccuracies in positioning and transmission of motion. Understanding and accounting for backlash is essential in gear design and application, as it impacts the performance and efficiency of mechanical systems.

The other options do not accurately describe backlash: friction refers to the resistance between surfaces, the distance when not engaged pertains more to initial spacing rather than engaged interaction, and resistance to motion does not specifically address the play in the gear teeth that characterizes backlash.