What is the purpose of idler gears?

Idler gears serve the essential role of reversing the direction of gear rotation. When a pair of gears is meshed directly, they rotate in opposite directions. An idler gear is placed between them to preserve the rotational direction of the driven gear while still allowing the driving gear to transfer motion accurately. By introducing the idler gear into the system, it enables the driven gear to maintain its desired orientation without changing the way the gears interact mechanically.

The other options highlight various functions not executed by idler gears. For instance, creating slippage is not a typical purpose of idler gears; instead, they aim to maintain a strong mechanical connection. Changing the revolutions per minute (r/min) of the driven gear is generally the function of gears with differing sizes rather than idlers, which do not alter the speed ratios themselves. Increasing efficiency is also not a primary function of idler gears; rather, their design can sometimes contribute to a smoother operation between gears without affecting overall efficiency negatively.