"电动机皮带轮" can be translated into English as "motor pulley" or "electric motor pulley".
"Motor pulley" is a concise and commonly used term, where "motor" refers to the electric motor and "pulley" denotes the wheel with a groove for a belt.
"Electric motor pulley" provides a bit more specificity, explicitly mentioning the type of motor (electric).
Both expressions are correct and can be used depending on the context and desired level of detail.