Which statement about belt trains is false?

A statement regarding belt trains that is deemed false would be that trains are connected by a single belt. In practice, belt trains are typically composed of multiple pulleys connected by multiple belts that can transmit power over longer distances and accommodate variable arrangements. This configuration allows greater flexibility in terms of speed changes and load distribution.

Statement A is accurate because belt trains generally have lower efficiency compared to gear trains, which can transmit more power for their size due to the direct meshing of gears.

Statement B correctly reflects the function of belt trains, as they are indeed utilized to alter the speed ratio between pulleys.

Statement C is also true; pulleys in a belt train commonly rotate in the same direction when connected by a belt, depending on the arrangement and routing of the belt itself.

Therefore, the assertion that trains are connected by a single belt is false, as belt trains can effectively utilize multiple belts for diverse mechanical advantages.