Which statement about idler gears is true?

The statement about idler gears being able to reverse the gear wheel direction is accurate. Idler gears are used in gear systems to change the direction of rotation without changing the overall gear ratio. When an idler gear is placed between two gears, it transmits the motion from the driving gear to the driven gear, effectively allowing the driven gear to rotate in the opposite direction of the driving gear. This is particularly useful in machinery where a specific orientation of rotation is required for proper function or operation.

Using idler gears does not inherently create slippage, change the revolutions per minute (r/min) of the driven gear in terms of its speed, or increase the efficiency of the system. Instead, their primary role is to facilitate directional change while maintaining the same speed ratio between the drive and driven components. Essentially, idler gears act as intermediaries in gear trains, and their effective use depends greatly on the specific configurations in which they are employed.