Belt drives transfer power using which force created between the belt and the pulleys?

Belt drives primarily rely on friction between the belt and the pulleys to transfer power. This frictional force is what enables the belt to grip the pulleys and, as a result, facilitates the movement and transmission of power from one pulley to another.

Friction is crucial in creating the necessary grip that prevents slippage; without adequate friction, the belt would simply roll over the pulleys without effectively transferring motion. In an operational context, when the driving pulley rotates, it essentially pulls the belt along due to the frictional grip, translating the rotational motion through to the driven pulley.

While torque plays a role in the mechanical advantage of the system, and heat can be generated due to the friction, neither of these forces are responsible for the power transfer itself in the context of a belt drive. The essential mechanism for that transfer is the frictional force acting between the belt and the pulleys, making it the key factor in the functionality of a belt drive system.