The use of continuously variable transmissions (CVT) has recently received increased attention due to their many benefits, like better fuel efficiency and quick acceleration. Surprisingly, CVTs aren't new technology.
"I saw my first CVT back in the 1960s on a little car made in Holland," Keith Johnson, senior automotive training instructor for American Honda Motor Co., Inc. says. "The company was DAF—now owned by Volvo—and the car's name was Daffodil 32. The CVT is a really unique concept, and has been tried by various manufacturers with varied success."
Before manufacturers started experimenting with CVTs in cars, Johnson says he saw the principle applied to very low horsepower applications like snowmobiles in the 60's and 70's back in Minnesota.
"Those belts were rubber, and in a situation where you would have people racing the snow mobiles, the belts would burn up because it couldn't handle the horsepower.
"When you start increasing the horsepower in a car engine, that belt mechanism has to be built sturdier." Johnson says most belts are now made of metal links like a watch band. Those little links are actually what make the CVT operate.
WHAT'S THE DIFFERENCE?
According to Jim Groat, technical development training manager for Ford Motor Company, a CVT works so well because it allows the engine to be in its most efficient power band a larger percentage of the time.
"The motor is not constantly trying to work harder to meet its power band, and so it really saves energy," he says.
Natae Cutler, product education and development for Toyota, explains that the spin rate of the engine can be selected to produce required power, but the spin is no faster than necessary, so that it maintains fuel efficiency and reduces exhaust emissions.
"With a CVT, it allows for the power to be revved really high while it lowers the engine spin rate to reduce losses associated with fast moving internal engine parts," she says.
It is important for fleets to keep in mind, when servicing CVTs, each manufacturer has its own modified version.
"We simply use a planetary gear unit that gives similar effects of a CVT. We don't have the belts and the pulleys that can loosen up or be damaged within the vehicle," Toyota's Cutler explains.
Yellow Cab Company in San Francisco is among the early adopters to run fifteen Ford Hybrid Escapes in their fleet. Each Escape has Ford's hybrid modified version of their CVT. Adnan Atallah, shop manager at Yellow Cab Company, says their warranty is up at 100,000 miles; that's still a good three to five months away for Yellow Cab.
"We haven't done any work on the modified CVTs, so we don't know how hard or how easy it is to work on. We change the oil, check the brakes—most of the preventative maintenance items are still the same. We just send it to the dealer when it pertains to the CVTs," he says.
Groat says Ford's CVTs are really very simple to work on.
"There are a few main components. Once you understand the principle on how they operate, CVTs are very easy to work with."
"They do require some special tools, as do most automatic transmissions," Groat says. "There is a large tool that is used to put together the variators on the transmission that would need to be purchased to service the internal components of the transmissions. Most of the failures that are likely to occur have something to do with the valve body, and that doesn't really require the assistance of special tools."
BACK TO SCHOOL
Despite the small number of CVTs Yellow pare his techs for additional training once the warranties expire.
"For some training information, we will go back to the dealer for seminars and general information. For larger components, we expect Ford's training personnel to come here and do their training in house," he says.
Groat explains that offering training information on vehicles has become an industry standard.
"Manufacturers are required to make their training available to the aftermarket. Some OEMs offer more information, and Ford just happens to offer all of the training that is available to our dealers to the aftermarket as well," he says.
"All of our training is available through motorcraft.com. Any of the aftermarket companies or fleets can go in and purchase the training through the website."
If Ford has provided a number of vehicles to a fleet, Groat says, Ford will actually go into the fleet's shop and offer them programs with trainers from Ford.
Cutler says Toyota also offers training to fleets called Toyota Hybrids General Service and Maintenance.
"It can be a course that can be a full day or modified for a half day depending upon the needs of the particular fleet," she says. "We as a whole go into detail as to how to fix just about everything. For fleets, we show them what the CVT looks like, discuss how it works, and what kind of trouble codes will come up if something goes wrong.
"However, when you get into the high voltage system, you do need our scan tool. With our Toyota software, you can see diagnostic trouble codes that you might not get if you use a generic scan tool. This may be a situation where they would need to take it to the dealership," says Cutler.
Toyota doesn't plan on stopping there. Cutler says there may be a more advanced fleet course that gets into more detail on the CVTs and other components in the future.
For Honda, this is a new and exciting market that has grown faster than they had expected.
Johnson says Honda is starting to see an increasing need for training, so they are already making plans to make sure fleets get the training they need.
"We have produced some training activities and materials that have been provided through our alternative fuels department," he says. "We have provided training to fleets through contractual instructors in the past. We are committed to any fleet that purchases vehicles from us that requests training and we are always developing ways to provide training and support."
KEEP IN MIND
Regardless of the manufacturer, one benefit for fleets all the manufacturers agree on is the simplicity of maintenance. Following the manufacturers' recommendations for maintenance procedures is the first step.
"One of the key components is that they have to be very, very careful not to mix the transmission fluid," Ford's Groat says. "If they put the wrong fluid in the transmission, they can destroy it in a hurry.
"That also comes into play when they are doing a flush and fill. Often fleets and quick oil change places will use machines to pump new fluid in and pump the old fluid out. If they do that service with that machine now, they will likely contaminate the CVT because they have some of the residual transmission fluid in the machine."
So far, fleets that own light duty vehicles with CVTs seem to be impressed by not only the efficiency, but also the performance.
Hal Mellegard, general manager of Yellow Cab Company, says the Ford Hybrid Escapes have performed, and continue to perform, better than he originally thought.
"We had some trouble with the water pump on about half of the Escapes. Ford took care of it, and it really was a learning experience for Ford and for us," he says.
Despite the minor glitch with the water pumps, the fact that the vehicles have required less maintenance, have better gas mileage and are expected to last longer, has persuaded Mellegard to probably purchase another ten or 20 new Hybrid Escapes when the new model year comes out.
"I want to see what these vehicles are like at 125,000 miles. We are continually evaluating their performance, but so far, we have no complaints," Mellegard says.