You use a brushed DC motor where the field coil is in series with multi tap resistor bank controlled by the throttle. That's how it was done with electric golf

You use a brushed DC motor where the field coil is in series with multi tap resistor bank controlled by the throttle. That's how it was done with electric golf carts before 1990. Article on 'speed switches' for old golf carts. http://www.golfcarcatalog.com/golf-cart-blog/golf-cart-speed-switches/ http://www.golfcarcatalog.com/golf-cart-blog/golf-cart-speed... Wiring diagram. https://wiringall.com/1984-ezgo-marathon-resistor-wiring-diagram.html https://wiringall.com/1984-ezgo-marathon-resistor-wiring-dia... Basically you use resistors to control the current in the motors field coil. Because the field windings have a lot of turns the current is much lower than in the armature. The armature is connected directly to the battery via a forward reverse switch.