Transmissions have evolved since the early days of motoring, but one type of transmission that may not be immediately familiar to you is the continuously variable transmission (or CVT). First marketed in 1989, CVT systems power many of today’s vehicles, including the Chrysler Pacifica Hybrid, Ford C-MAX Hybrid, Subaru Forester, and a range of Nissan and Infiniti models. But how does a CVT work, and how does it compare to traditional automatic transmissions? Let’s have a look.

Gears vs CVT: How They Work

The job of any transmission is twofold—to transfer power from the engine to the wheels of your vehicle, and to ensure that your engine’s rpm ratio remains within the optimal range when the car is in operation. Both geared and CVT transmissions accomplish this goal, but they do so in different ways.

A traditional automatic (geared) transmission, uses a set of 4 to 8 gears of fixed sizes to match your engine’s rpms to whatever job your car is doing at the time. Low revolutions per minute (rpms) increase traction for low speeds, slick surfaces, climbing, hauling, or towing, while higher rpms are used for higher speeds, like highway driving. As demand on your engine increases or decreases, a traditional automatic transmission shifts to the most appropriate gear ratio.

In contrast, a CVT transmission has no gears, and instead uses two variable-width pulleys joined by a flexible belt. When the pulley sheaves are far apart, the pulley acts as a small gear, and when the sheaves are close together, the pulley acts as a large gear. Because the belt length does not change, the sheave of the input and that of the output are adjusted simultaneously to keep the belt taut.

Pros and Cons of CVTs

Pros

Perhaps the greatest advantages of CVT are that it delivers seamless shifting and responds instantly to changes in power demand, both of which translate into smoother acceleration and deceleration. A CVT also eliminates harsh or abrupt shifting when more power is needed for passing. Similarly, CVT eliminates “gear hunting” often experienced by drivers with standard transmission (clutch) vehicles. And a CVT is no slouch when it comes to climbing, hauling, or towing—quickly shifting to low for increased traction. Because CVTs are lightweight and fuel efficient, they are frequently the first choice among hybrid vehicle manufacturers.

Cons

Some drivers have reported that the absence of fixed gears makes them feel less engaged in the act of driving. Also, during acceleration, the CVT can cause the your vehicle to emit a droning sound because it operates at high rpms until reaching its target speed. CVTs are also prone to some of the same problems that plague traditional transmission configurations—such as slipping, jerking, and shuddering. CVT belts are also not foolproof, and have been noted to suffer high degrees of wear and stretching.

Trouble Signs

If you believe your CVT is not operating as it should, there are some trouble signs you can check for.

  • Puddling of fluid under your vehicle
  • Your transmission fluid emits a burnt odor
  • You experience performance issues such s slipping

Maintenance

As with any transmission, a CVT can only operate at its best when properly maintained. Most automakers recommend regular transmission service and fluid checks every 30,000 to 50,000 miles, though Nissan recommends 25,000 mile maintenance for its CVT vehicles.

At Main Line Transmissions, our skilled technicians are familiar with every currently produced transmission, including CVTs. We can repair or service your vehicle promptly as well as offer helpful tips on keeping your transmission operating at its best.

Need a transmission check up? Drive in and see us at Main Line Transmissions!