Which device is commonly used to change the direction of motion in a belt drive system?

• A. Pulley
• B. Gear
• C. Sprocket
• D. Cam

Answer: (A)

To change the direction of motion in a belt drive, you route the belt around pulleys. A pulley is a wheel with a groove that the belt sits in, so when the belt is guided onto a different pulley, its path—and thus the driven shaft’s direction—changes. Pulleys are the standard way to redirect belt motion because they simply redirect the belt without inherently altering the speed ratio unless you change pulley sizes.

Gears rely on meshing teeth and are used in gear trains, not belt systems, so they don’t route a belt. A sprocket is used with chains, not belts, so it doesn’t apply to belt direction changes. A cam is a rotating piece that converts rotary motion into a controlled reciprocating motion, not a device for redirecting belt travel.