Non-synchronous Automatic. Variomatic is the stepless, fully automatic transmission of the Dutch car manufacturer DAF , using a drive belt and two pulleys. It was the first continuously variable transmission CVT as opposed to shifting between separate gears. In theory, this always produces the optimum torque. The variomatic was introduced by DAF in , also putting an automatic gear box in the Netherlands for the first time. The variomatic was introduced on the DAF
|Published (Last):||7 August 2010|
|PDF File Size:||7.15 Mb|
|ePub File Size:||9.89 Mb|
|Price:||Free* [*Free Regsitration Required]|
Non-synchronous Automatic. Variomatic is the stepless, fully automatic transmission of the Dutch car manufacturer DAF , using a drive belt and two pulleys. It was the first continuously variable transmission CVT as opposed to shifting between separate gears. In theory, this always produces the optimum torque. The variomatic was introduced by DAF in , also putting an automatic gear box in the Netherlands for the first time.
The variomatic was introduced on the DAF Because the system does not have separate gears, but one continuously shifting gear and a separate 'reverse mode' as opposed to a reverse gear , the gear works in reverse as well, giving it the interesting side-effect that one can drive backwards as fast as forwards. As a result, in the former Dutch annual backward driving world championship, the DAFs had to be put in a separate competition because no other car could keep up.
Thus, these very cheap and simple cars were the 'formula one' in this competition. Manual transmission remained dominant in Europe. Audi reintroduced an improved version of the variomatic in the early 21st century under the name Multitronic. This system uses a metal belt and lacks a limit to the number of gears available, switching between them without noticeable shocks. These metal drive belts are the most important part of CVT.
The only factory still producing these belts, the Bosch factory in the Netherlands, produced the ten millionth belt on 9 May It is used in over 40 car models, these days even including expensive brands like Mercedes. The final drive has two pulleys with moveable conical drums.
The distance between the drums is controlled by the engine vacuum in the inlet manifold and engine RPM , through centrifugal weights inside the drums. Between the two pulleys runs a drive belt. As a result of change in the distance of the conical drums in both pulleys, the diameters and so also the reduction ratio changes continuously.
With the DAF - 55 each rear wheel was propelled individually by a pair of conical drums and drive belt with the effect of a limited slip differential : if a drive wheel on slippery road revs up, the other wheel can still transfer the full torque.
This results in unusually good traction characteristics, which were also a reason for successes of the DAFs in rallies. It was even used in a Formula 1 car, but it was only allowed to start in one race before it was banned since it gave an unfair advantage.
There were several disadvantages that accompanied the lack of a true differential gear. Although each belt could settle independent of the other into it's optimum position, thus allowing for wheel speed variation, the system was slow to operate and depended on the pulleys being turned.
This led to rapid tire wear and placed stress on other transmission components. Snapped drive shafts were common. Low speed handling in icy conditions was interesting as the system tended to drive the car forward against the influence of the steered wheels. Later cars, the 46, 66 and Volvo variants were fitted with a differentially geared axle.
The Variomatic is also used in today's motorscooters. It is a standard part of all common scooters since , and several companies such as Malossi , Polini , Doppler and Stage6 are offering tuning clutches and variomatic for most common 50, 70 and cc scooters. Rather than rubber drive belts, the modern transmission is made much more durable by the use of steel link belts. Jump to: navigation , search. Categories : Automotive transmission technologies Automatic transmission tradenames. Continuously variable Variomatic Multitronic.
Bicycle gearing Derailleur gears Hub gears. Car body style and classification. Amphibious vehicle. Engine configuration. Car engine. Warm air intake. Ignition system. Interior equipment. Motor vehicle theft deterrence.
Wheels and Tires.
What is a CVT gearbox?
The meaning of the abbreviation CVT is Continuously Variable Transmission, and it's a type of single-speed automatic gearbox. The CVT gearbox has been used in a variety of cars, but you'll usually find it fitted to a small car. Its compact size and simplicity of construction means it's more cost-effective to use in a small car than a conventional automatic gearbox. In many ways a CVT gearbox is similar to a regular auto. For starters, there is no clutch pedal in a CVT-equipped car, so you can drive it on an automatic-only UK driving licence. You'll also find that if a car is offered with a CVT gearbox, it will be more expensive than the same model with a manual gearbox, just like a regular auto. If you compared them back-to-back, the manual model would have better claimed fuel economy, too.
HOW IT WORKS: CVT
Variomatic is the continuously variable transmission CVT of the Dutch car manufacturer DAF , originally developed by Hub van Doorne :  It is a stepless, fully automatic transmission consisting of a "V" shaped drive belt and two pulleys , each of two cones, whose effective diameter can be changed so that the "V" belt runs nearer the spindle or nearer the rim, depending on the separation of the cones. These are synchronized so that the belt always remains at the same optimal tension. It was the first commercially successful CVT as opposed to shifting between separate gears. In theory, this always produces the optimum torque.
Although Hub van Doorne, one of the original founders of DAF, has been credited with developing the belt-driven variable transmission, the principle for a stepless transmission can be traced back the late 15th century and Leonardo di Vinci. The credit for developing the first operative variable speed transmission goes to Milton Reeves in the late 19th century who produced a version to power a sawmill. By the end of the first decade of the 20th century, Zenith Motorcycles were producing a twin-cylinder powered machine equipped with what the company described as the Gradua-Gear system, a much-improved version being used by Rudge-Whitworth in As engine speed increased and decreased, centrifugal force constantly altered the gap between the two sides of the pulley. This caused the belt transferring power to the differential to either speed up or slow down according to how high or low it was riding inside the adjustable pulleys. The idea was further developed in the mids in the Netherlands by Hub Van Doorne. Vacuum from the engine and centrifugal weights inside the primary and secondary drums or pulleys caused the ratios to change up and down continuously according to how fast or slow the engine was running and what load it was under.
You may know that Google is tracking you, but most people don't realize the extent of it. Luckily, there are simple steps you can take to dramatically reduce Google's tracking. Completely depends on the driver. The concept says it is a more efficient drivetrain when driven efficiently, but, most do not drive for economy. Be prepared for many contradicting answers on this question, that will move over into manual vs automatic vs CV transmissions.