Do electric cars have gears? A guide to what drives your electric vehicle

If this is your first time driving an electric vehicle, your car may not even have a gear stick or gear stick that you can use to change gears. Step on the accelerator (not the “accelerator”) and you won’t feel a gear shift. Do electric vehicles even have gears?

The answer depends on who you ask. Search reputable automotive websites and you will find answers ranging from “no gearbox” to “some type of gearbox” and “a single-speed gearbox”. Here we clarify the facts and get to the bottom of what drives your electric vehicle.

What does a transfer do?

It helps define what a transfer does first. A gearbox is a machine that transmits power, which is why every car has a gearbox in the strictest sense of mechanical engineering.

A vehicle transmission transmits the rotational force of the energy source, be it an electric motor or an internal combustion engine (ICE), via a set of gears to a differential, the unit that turns the wheels. But in common parlance, many people think of the transmission as part of an engine that shifts gears from low speed to high speed or from forward to reverse, as in “manual” and “automatic” transmissions. It gets cloudy there.

A conventional transmission

In a gas-powered car, an internal combustion engine has to rotate at different speeds so that it neither stalls (because it rotates too slowly) nor overheats (because it rotates too quickly). This range is approximately between 500 and 7,000 revolutions per minute (RPM). To compensate for this limitation, the transmission adjusts the ratio between the rotation of the engine and the rotation of the wheels by switching between lower and higher gears.

An automatic transmission in a gas-powered vehicle.

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The rotation of the lowest gear is slower than the engine so that the engine can run at high enough speeds not to stall. The lowest gear rotates slowly because it is the largest gear that transfers more power but less speed to the wheels as the gear must move the vehicle forward from a standstill.

The highest gear, on the other hand, is the smallest and runs in “overdrive”, ie it rotates faster than the engine, so that the car can drive at high speed without the engine overheating. On a vehicle with a manual transmission, engaging the clutch disengages one gear so that you can shift into another. An automatic transmission does the same thing, but without driver intervention.

What is horsepower?

The performance of a motor is defined by speed and torque. Speed ​​is defined as the speed at which the motor rotates while torque is the amount of rotational force that the motor exerts. When a motor turns quickly with constant power, it loses torque. When it turns slower, the torque is increased.

How does an EV motor work?

One of the distinguishing features of electric vehicles is their quiet, instant and smooth acceleration. Because the drive in an electric vehicle works differently. As the name suggests, the main difference between electric vehicles and gasoline-powered cars is the source of fuel. When you step on the accelerator pedal on an electric vehicle, electricity is sent from the battery to the electric motor, which spins quickly.

An electric vehicle transmission.

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Most electric vehicles have a single AC motor connected to a gearbox. What’s in the gearbox is called a gearbox by some because it’s actually a set of gears that transfers the rotation of the motor to the rotation of the wheels. More precisely, however, it is referred to as a single-stage reduction gear, since the several gears in the gearbox are always connected to one another and thus all spin at the same time.

The reduction gear reduces the speed of the motor in a ratio of about 10 to 1 to the more sensible speeds of the wheels. So there is no clutch, no disengagement of gears and no shifting between gears of different sizes depending on the needs of the vehicle – so no transmission.

Is there a reverse gear?

Since the motor of an electric vehicle usually works with alternating current, no reverse gear is required. The motor just turns in the opposite direction.

An AC motor can rotate between zero and 10,000 rpm or more. (The motor in a 2021 Tesla Model S Plaid can spin up to 23,308 RPM, one of the reasons it can accelerate up to 300 mph.) This gives electric vehicles plenty of torque with a “sweet spot” over a wide range of speeds “. ”Between enough torque and sufficient speed in the range of 30-40 mph. The energy is conducted directly and almost instantaneously from the engine via the gearbox to the wheels and not via a gearbox.

The lack of a gearbox reduces the friction (and therefore wear) that arises when engaging and disengaging multiple gears. The smooth transition also keeps a vehicle moving forward better than shifting gears, which is one of the reasons electric vehicles are much more efficient with energy.

Overall, an electric vehicle converts, on average, 77% of the electricity stored in its battery to get the car moving, while a gas-powered car converts from 12% to 30% of the energy stored in its petrol tank. Much of the rest is wasted as heat. The transmission power from the motor of an electric vehicle to the wheels is 89 to 98% efficient, depending on the vehicle, while in an ICE car the same process from the motor to the wheels is only 14 to 26% efficient.

Can electric cars have multiple gears?

Any vehicle, whether it’s an internal combustion engine or an electric vehicle, needs more torque than speed to bring the car from a standstill and more speed than torque when the vehicle is already pushing forward. So wouldn’t electric vehicles benefit from having multiple gears? Yes, but at the expense of a more complex system that requires more parts, more weight, more labor, and a larger supply chain – in other words, more upfront and maintenance costs for the consumer.

Some newer electric vehicles, including the Audi e-tron GT and the Porsche Taycan, have multiple gears that allow them to deliver more torque to the wheels for increased acceleration. The planned Jeep Magneto will even have a manual transmission with multiple gears. Racing cars like those of the fully electric Formula E also have transmissions.

When electric trucks, especially 18 wheelers, hit the market it is possible for them to have multiple gears and transmissions, but given the wide range of revs possible with an electric motor, they can only have two: one for torque , the other for cruising speed, with the shift from one to the other being about 30 mph. (The upcoming Tesla Semi will only have a single-stage reduction.) The same goes for smaller vehicles where the ability to pull or carry heavy loads is important.

Stepless gear

Some ICE and hybrid vehicles have continuously variable transmissions (CVT), a form of automatic transmission that accelerates seamlessly from speed to speed using pulleys in place of gears. Recently, electric vehicle CVT systems have been introduced that can increase torque at lower speeds to accommodate heavier vehicles and loads. This eliminates the need for EV engineers to find a “sweet spot” compromise between torque and speed.

CVT systems promise greater efficiency and can enable electric vehicles to extend their range – a key concern of potential buyers of electric vehicles.

Multiple engines instead of multiple gears

Tesla Model S twin-engine, electric-powered sedan.

Sjoerd van der Wal / Getty Images

Some EVs solve this problem by having multiple motors with different gear ratios to deliver more or less torque depending on the needs of the vehicle, with electronics switching electrons to different motors more efficiently than a transmission shifting gears less efficiently. The powerful Lucid Air, for example, like many Tesla vehicles, is available as a dual or tri-motor version.

And in contrast to the gears in an ICE vehicle, the multiple motors in an EV can be used at the same time, which gives the vehicle both speed and torque, more traction or more agility. Rivian’s electric pickup trucks even have independent motors on each wheel that allow the truck to “turn the tank”.

Buckle up

The future of electric vehicles is open and constantly offers new ways of delivering propulsion. Elon Musk even promises that the next iteration of the Tesla Roadster will have a “SpaceX Cold Gas Thruster System”. Buckle up your seat belts and stay tuned.