CVT Transmission? How Does It work?

John Baker|Mar 27, 2019 11:18 AM

“CVT” stands for continuously variable transmission. A CVT transmission uses a pair of variable-diameter pulleys and a belt or chain to provide unlimited gear ratios.

How does a CVT work?

To illustrate, think of a traditional automatic or manual transmission. They’re built with a defined number of gears, for example first through sixth (plus reverse). The transmission can operate in only one gear at a time. You typically feel a slight surge with each gear change.

CVTs, however, offer unlimited gear ratios.

Take a look at the image. You can see the metal belt connecting the two pulleys. Depending on engine speed and load, the computer automatically varies the pulley sizes to ensure the optimal gear ratio for the driving conditions.

CVT transmission pros and cons

What good does that do?

Imagine pedaling a bike. As you approach a steep hill, you adjust the shifters so a smaller chainring attached to the pedals is driving a larger sprocket on the rear wheel. This reduces the effort required to move the bike.

When you reach a stretch of flat road, you adjust the gear ratio again so a larger chainring attached to the pedals is driving a smaller sprocket. This helps achieve the perfect balance between energy expended and bicycle speed.

The same principle applies to a CVT, except the computer does all the thinking for you. When starting from a dead stop, it varies the pulley diameters (smaller drive pulley and larger driven pulley) so the engine can move the car as efficiently as possible. As you accelerate, it continuously varies the pulley sizes to keep the engine in its “sweet spot,” which results in improved fuel economy. Plus, you never feel the gear engagements because, in effect, there aren’t any.

CVTs gaining in popularity – but there are negatives

These benefits are why many car makers, including Nissan, Honda and Toyota are introducing more vehicles with CVTs.

There are drawbacks, however, including the “rubber-band effect” (you rev the engine, yet it takes a moment for vehicle speed to catch up) and lack of driver involvement (zero fun). In addition, most CVTs’ relatively diminutive parts can’t handle the power and torque of the truck or SUV you use to tow your boat or camper, which is why you find them mostly on smaller cars. Although there are some exceptions, as the list shows, which shows popular vehicles with a CVT.

What cars have a CVT transmission?

Honda Accord
Honda HR-V
Mercedes-Benz A- and B-Class
Nissan Altima
Nissan Pathfinder
Subaru Forester
Subaru Impreza
Subaru Legacy
Subaru Outback
Toyota Camry
Toyota Highlander Hybrid
Toyota Prius

Slip into something special

One look at the guts of a CVT and you can’t help but wonder how the belt doesn’t just slip wildly over the pulleys.

Believe it or not, the transmission fluid plays a major role in ensuring the belt or chain remains in contact with the pulleys without slipping.

That’s why CVTs require specialized CVT transmissions fluids, and not the traditional automatic or manual transmission fluid you probably have in your garage. CVT transmission fluids must be formulated with the correct frictional requirements to guard against slipping. Using the wrong fluid will reduce performance and potentially wreck your transmission.

Wear protection also important

Solid wear protection is also vital to maximizing CVT performance and life. That’s why we designed AMSOIL Synthetic CVT Fluid to fight wear and help extend transmission life.

To demonstrate, we pitted AMSOIL Synthetic CVT Fluid against Nissan NS-2 CVT Fluid in a field trial. After 100,000 miles, the belt lubricated with AMSOIL Synthetic CVT Fluid demonstrated minimal wear, as you can see in the images. This helps you get the best performance and most life out of your CVT.

The belt lubricated with Nissan NS-2 CVT Fluid demonstrated increased wear.

Buy AMSOIL Synthetic CVT Fluid

While driving purists may initially scoff at the notion of a transmission that requires no driver input, many eventually warm up to CVTs’ increased gas mileage and smooth operability.

If you’re one of them, make sure you protect it with a good CVT transmission fluid.

Never Overlook This When Maintaining Your Snowblower

John Baker|Nov 06, 2018 10:01 AM

Thanksgiving day, 2016. While my family was gathered in my dining room, imbibing spirits and making merry, I was in the shed disassembling the carburetor on my snowblower, reeking of petroleum as rivers of gasoline flowed under my jacket cuffs and saturated me to the elbows.

Here’s what happened, and here’s how to avoid it.

Snowblower maintenance can be distilled to this Golden Rule: Maintain your fuel system.

I’ll say it again: Maintain your fuel system.

A snowblower that won’t start is almost always due to a fuel problem. And nothing raises your blood pressure like a dead snowblower following the season’s first snowstorm. You know it! We always wait to the last minute on that first snow.

Preventing fuel-system problems starts in the spring prior to storage.

Leave the carburetor full of gas

This is where everything unraveled for me. One theory says that shutting off the fuel line and running the engine until the carburetor empties helps prevent varnish that plugs the jets and prevents starting.

Wrong, at least in my case. As I discovered, leaving the carburetor empty and exposed to air hastens oxidation and varnish. Fluctuating temperatures and humidity throughout the summer invite varnish, and it doesn’t take much to plug the tiny orifices in a carburetor. Then, it’s just a matter of time before you’re stinking of gasoline on Thanksgiving day while blasting carb cleaner on everything within reach.

Instead, add fuel stabilizer at the end of the season, run the engine for a few minutes to distribute the treated gas throughout the system, then shut down the engine. Now you can shut off the fuel line for the summer. The treated fuel in the carburetor bowl provides protection and helps keep components clean.

Some people claim you should run the carburetor empty since the gas will evaporate anyway. That may be true, but evaporation takes time, and the carburetor will at least be protected in the interim.

Stabilize the gas

As mentioned, treat gas with stabilizer prior to storage. Stabilized fuel protects against oxidation and varnish throughout the summer.

Use ethanol-free gas

When water infiltrates your gas tank in the form of melted snow, it can cause phase separation, a phenomenon that occurs when the bond between ethanol (present in most gasoline sold today) and gasoline breaks. When this ethanol/water mixture enters the combustion chamber, it creates a lean-burn situation that can damage your engine.

For best performance, use 91-octane, non-oxygenated (ethanol-free) gas. Many gas stations offer non-oxygenated gas and advertise it for powersports and off-road use. It’s a little more expensive, but spending a few extra dollars a winter to help your $1,000 dollar machine run strong isn’t a factor, in my opinion. At the very least, use ethanol-free gas during storage to help ward off phase separation.

Perhaps test your gas to see if it is really and truly ethanol free. I know many who say “I never use ethanol” and after testing the source gasoline it turned out to be laced with ethanol! Put your gas in a glass jar and see if you see it separate over time. Sometime you need to shake it up.

(Find out how to fight ethanol problems in small engines.)

If you use ethanol-blended gas, consider continuous use of a fuel additive, such as AMSOIL Quickshot, formulated to address ethanol-related performance issues.

Change The Oil in the Spring

Used oil contains acids that can slowly corrode metal components. Prior to storage, change the oil to remove acidic byproducts and ensure maximum protection throughout the summer. After changing oil, I like to run the engine for a couple minutes to distribute oil throughout the lower end of the engine.

Fog the engine

Use fogging oil to protect the upper end (cylinder, piston, valves) from corrosion during storage. Remove the spark plug, which provides the perfect time to inspect its condition, and spray a little oil into the cylinder. Slowly pull the starter cord a few times to distribute the oil, then replace the plug.

Check the gear housing – It can fail!

Clean any debris from around the filler port on the auger gear housing, remove the plug and ensure the gear lube level is up to the top. If not, add the correct lubricant (check your owner’s manual for viscosity).

Inspect belt condition and linkages

Stressing a worn belt after it’s sat idle for months is a recipe for a breakdown. When a belt does break, it’s often while clearing the first big snowfall of the year. Spring is the prime time to check the condition of drive belts and linkages. It’s much easier and far more comfortable to crawl around your snowblower on a mild, spring day than in the winter.

One final word of advice: Keep an eye on the weather at the start of winter. When the forecast calls for the first snowstorm of the season, start your snowblower a few days early to ensure it’s ready to go.

That gives you plenty of time if your snowblower won’t start – like about two hours on Thanksgiving day – to fix any problems.

Tag: belt

What is a CVT Transmission?