German to English Tech/Engineering Mechanics / Mech Engineering mechanical separator

there is a drawing which shows a kind of wheel to which is attached a drive belt that drives a rotating drum. The wheel itself protrudes from a motor.
My first inclination is to call it a drive-wheel - but then why isn't the German "Antriebsrad" or "Antriebsscheibe"? I also found "pulley" in this context, but it doesn't have that function. The picture shows a series of "wheels" connected by belts as a sort of gearing or drive system.