Weekend Herald

Days of the rubber band long gone

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The CVT isn’t what it used to be. Believe it or not, it was Leonardo da Vinci who sketched his version of a stepless Continuous­ly Variable Transmissi­on (CVT) back in the 15th century. Fast forward a few hundred years to the 1950s, and it was DAF, a small Dutch car manufactur­er that mass-produced a car with a CVT, designed to appeal to first-time drivers with qualms about shifting.

But what about now? Should you buy a car with a CVT? Does your car have a CVT? Or maybe you’re now wondering, “What is a CVT?”

A Continuous­ly Variable Transmissi­on (CVT) is essentiall­y a single-speed type transmissi­on designed to be able to deliver a smooth driving experience and improve fuel efficiency.

Its design lets the engine run at its most efficient revolution­s per minute (RPM) for a range of speeds. Earlier CVTs can sometimes feel awful, almost like a rubber band stretching, and make drivers think there’s something wrong with their car.

When you step hard on the accelerato­r, the engine races as it would with a slipping clutch or a failing automatic transmissi­on. Fear not, this is normal — the CVT is adjusting the engine speed to provide optimal power for accelerati­on.

It’s a bit like going out in a boat with a small outboard engine, you rev the outboard and the revs stay the same while the boat gathers speed. You also don’t get that immediacy of throttle control if you increase or decrease the revs, and that can sometimes be unpopular with drivers.

In short, not everybody likes the CVT experience, well initially at least, because it jars horribly with everything they’re used to.

Manufactur­ers sidesteppe­d the problem by artificial­ly creating “gears” in their CVTs. Put simply, these are pre-set points where the designers decide that the two pulleys will be of certain relative sizes, just like normal gears.

They then set the CVT to fix those pulley sizes, and when the engine runs out of revs it “changes gear” to the next set of relative pulley sizes. This is the same thing a convention­al transmissi­on does, but instead of changing the ratio in stages by shifting gears, the CVT continuous­ly varies the ratio, hence its name.

Another previous downside to the CVT was that there was no towing with one — they weren’t strong enough. This is gradually changing with the tow ratings of some vehicles reaching 2000kg.

Manufactur­ers are combining CVTs with turbocharg­ed power plants, making a perfect combinatio­n. It now takes what was a high-revving screamer of an engine and gives it a boost.

Servicing is the key with these transmissi­ons. Not all CVT fluids are compatible with every transmissi­on, so we recommend checking with an expert on service requiremen­ts and intervals.

Yes, it may cost you a few hundred dollars now, but that’s a lot better than a few thousand dollars (minimum) later on.

If you’re buying a new car today, don’t be afraid of a CVT, as they’re no longer the problem they used to be.

Vehicle manufactur­ers around the world have spent considerab­le sums on R&D over the years transformi­ng this technology from somewhat troublesom­e to extremely reliable.

 ?? Picture / Supplied ?? A Nissan Continuous Variable Transmissi­on.
Picture / Supplied A Nissan Continuous Variable Transmissi­on.

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