Do Electric Cars Have Transmissions?

The simple answer is, yes, electric vehicles (EV) have a transmission. But it’s nothing like the ones found in internal combustion engines (ICE), which have powered cars for the last 100 years.

A few years ago, a co-worker asked if I’d like to take a spin in his new EV, knowing I wasn’t a fan of them. The ride was much rougher than expected, especially when cornering. However, I was surprised and impressed by the sleek appointments and flawless acceleration, while anticipating harsh transmission upshifts that never came.

When I asked what kind of transmission the car had, the answer was even more shocking — a single-speed gear box. How is that even possible? Here’s what you need to know.

What Does a Transmission Do?

A transmission transfers an engine’s rotating power to the wheels. Your car won’t move without one. Technically, anything that transmits power from one part to drive or turn another, whether a washing machine, bicycle or car, is considered a transmission.

Types of Transmissions

All traditional vehicle transmissions do the same thing but in different ways. Here are the most common transmissions found in ICE cars and trucks today:

• Manual transmission: Shifting gears on this kind requires the driver to depress the clutch pedal, disengaging the engine from the transmission. The driver then uses the gear shifter to physically move gearsets inside the transmission.
• Automatic transmission: Once you put your vehicle in drive, pressurized automatic transmission fluid travels through a network of channels that, depending on engine load and gear selection, locks and unlocks gearsets. This makes shifting automatic, hence the name.
• Automated manual transmission: An automated manual also uses a mechanical clutch. Electronic, pneumatic or hydraulic control buttons allow for fully automatic or manual shifting, using the gear shifter or steering wheel-mounted shift paddles. Developed for racing cars, shift paddles allow drivers to shift gears in electrically controlled transmissions without engaging the clutch.
• Continuously variable transmission (CVT): This employs belts, pulleys and sensors in place of gears. It produces an almost limitless number of seamless shifts without pausing for gear changes, affording smooth acceleration and enhanced fuel economy.

How Does an EV Transmission Work Differently Than an Internal Combustion Engine Transmission?

EVs use a one-gear, one-speed transmission to transfer all the motor’s power directly to the wheels. ICE use multi-gear, multi-speed transmissions. Modern multi-gear transmissions can produce up to 10 gear speeds (ratios).

How does an EV operate on only one gear?

First, it’s all about how quickly an EV’s motor can quickly reach full power (torque) from zero revolutions per minute (rpm). This is known as instant torque; it’s the reason EVs require dedicated tires. Second, single-gear EV transmission ratios are precisely calculated for each vehicle to increase electric motor efficiency and transmit just the right amount of power from the motor to the wheels.

Multiple-speed transmissions help an ICE vehicle reach peak performance over time and distance. An EV can achieve full power almost instantaneously through a single gear. Without differential gears, software regulates electric motor and wheel speeds, allowing each to rotate at different speeds when turning.

Also, an ICE motor spins only in one direction and needs a transmission to go into reverse. An EV motor spins in both directions so it needs only one gear. Placing the car into “Reverse,” spins the motor(s) in the opposite direction from “Drive,” allowing you to move backward.

In theory, having a single gear and being in high gear, an EV can travel as fast in reverse as it can in drive (but don’t try this!). This isn’t possible with a traditional ICE/transmission pairing because reverse is the same as low gear.

Eliminating gear shifting results in a smoother, quicker and quieter acceleration. And with only one gear, EV’s convert more than 77% of energy that charges their batteries to power at the wheels. ICE vehicles convert about 12% of the energy stored in gasoline.