Variomatic
Encyclopedia
Variomatic is the stepless, fully automatic transmission
Automatic transmission
An automatic transmission is one type of motor vehicle transmission that can automatically change gear ratios as the vehicle moves, freeing the driver from having to shift gears manually...

 of the Dutch
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 car manufacturer DAF
DAF Trucks
DAF Trucks NV is a Dutch truck manufacturing company and a division of PACCAR. Its headquarters and main plant are in Eindhoven. Cabs and axle assemblies are produced at its Westerlo plant in Belgium...

, originally developed by Hub van Doorne
Hub van Doorne
Joseph Josephus Hubert van Doorne was the founder of Van Doorne's Aanhangwagenfabriek and of Van Doorne's Automobielfabriek known, especially to non-Dutch speakers, as DAF, together with his brother Willem van Doorne.-Early years:Van Doorne was born in America, a confusingly named small town...

: this consists of a "V" shaped drive belt and two pulley
Pulley
A pulley, also called a sheave or a drum, is a mechanism composed of a wheel on an axle or shaft that may have a groove between two flanges around its circumference. A rope, cable, belt, or chain usually runs over the wheel and inside the groove, if present...

s, 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 continuously variable transmission
Continuously variable transmission
A continuously variable transmission is a transmission that can change steplessly through an infinite number of effective gear ratios between maximum and minimum values. This contrasts with other mechanical transmissions that offer a fixed number of gear ratios...

 (CVT) (as opposed to shifting between separate gears). In theory, this always produces the optimum torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....

. The variomatic was introduced by DAF in 1958, also putting an automatic gear box in the Netherlands for the first time. The variomatic was introduced on the DAF 600
DAF 600
The DAF 600 is a small family car that was DAF's first production passenger car: it was first presented at the Amsterdam Motor Show in February 1958 and was in production by 1959, although the firm had published the first details of the car at the end of 1957...

. 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
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...

 remains dominant in Europe. When DAF was taken over by Volvo, the Variomatic patents were transferred to a company called VDT (Van Doorne Transmissie), later taken over by Bosch. VDT continued development of the CVT and introduced a pushband system in the Ford Fiesta and Fiat Uno. Audi
Audi
Audi AG is a German automobile manufacturer, from supermini to crossover SUVs in various body styles and price ranges that are marketed under the Audi brand , positioned as the premium brand within the Volkswagen Group....

 reintroduced an improved version of the variomatic in 2000 under the name multitronic
Multitronic
multitronic is a stepless transmission launched by AUDI AG in late 1999, jointly developed and manufactured by LuK.Based on the principles of continuously variable transmission popularised by DAF, multitronic offers a stepless automatic transmission in which the ratio between the input shaft and...

. 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
Robert Bosch GmbH
Robert Bosch GmbH is a multinational engineering and electronics company headquartered in Gerlingen, near Stuttgart, Germany. It is the world's largest supplier of automotive components...

 factory in the Netherlands, produced the ten millionth belt on 9 May 2007. It is used in over 40 car models, these days even including expensive brands like Mercedes-Benz
Mercedes-Benz
Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...

.

The final drive has two pulley
Pulley
A pulley, also called a sheave or a drum, is a mechanism composed of a wheel on an axle or shaft that may have a groove between two flanges around its circumference. A rope, cable, belt, or chain usually runs over the wheel and inside the groove, if present...

s with moveable conical drums. The distance between the drums is controlled by the engine vacuum in the inlet manifold
Inlet manifold
In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders...

 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
Gear ratio
The gear ratio of a gear train is the ratio of the angular velocity of the input gear to the angular velocity of the output gear, also known as the speed ratio of the gear train. The gear ratio can be computed directly from the numbers of teeth of the various gears that engage to form the gear...

 changes continuously.

With the DAF 600 - 55 each rear wheel was propelled individually by a pair of conical drums and drive belt with the effect of a limited slip differential
Differential (mechanics)
A differential is a device, usually, but not necessarily, employing gears, capable of transmitting torque and rotation through three shafts, almost always used in one of two ways: in one way, it receives one input and provides two outputs—this is found in most automobiles—and in the other way, it...

: 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. There were several disadvantages that accompanied the lack of a true differential gear. Although each belt could settle (independent of the other) into its 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.

A version with a differential was developed by Williams
WilliamsF1
Williams Grand Prix Engineering Limited, trading as AT&T Williams, is a British Formula One motor racing team and constructor. It was founded and run by Sir Frank Williams and Patrick Head...

 in the 1993 Williams FW15C
Williams FW15C
The Williams FW15C was a Renault-powered Formula One car designed by Adrian Newey and built by Williams Grand Prix Engineering. It was raced by Alain Prost and Damon Hill during the 1993 Formula One season....

 CVT Formula One
Formula One
Formula One, also known as Formula 1 or F1 and referred to officially as the FIA Formula One World Championship, is the highest class of single seater auto racing sanctioned by the Fédération Internationale de l'Automobile . The "formula" designation in the name refers to a set of rules with which...

 car, but it was banned before being raced.

The Variomatic is also used in today's motorscooters. It is a standard part of all common scooters since 1985, and several companies such as Malossi
Malossi
Malossi S.p.A. is an Italian manufacturer of tuning parts for mopeds and scooters. It was founded by Armando Malossi in 1930.Among other products, Malossi produces cylinders and variators for both racing and road use...

, Polini
Polini
Polini S.p.A. is an Italian manufacturer of tuning parts for motorcycles, mopeds and scooters. Among other products, they produce cylinders and variators for both racing and road use.They also produce pocket bikes with 50cc up to 15hp....

, Doppler and Stage6 are offering tuning clutches and variomatic for most common 50, 70 and 125 cc scooters.

A version of the Variomatic called Transmatic is still made by DAF's Van Doorne's Transmissie b.v. in Tilburg
Tilburg
Tilburg is a landlocked municipality and a city in the Netherlands, located in the southern province of Noord-Brabant.Tilburg municipality also includes the villages of Berkel-Enschot and Udenhout....

, The Netherlands and Nissan Primera
Nissan Primera
The Nissan Primera is a medium sized family car produced by the Japanese automaker Nissan for the Japanese domestic and European markets.-Nissan Primera P10 :...

 is offered with this transmission.

Today the CVT works according to the same principle of split pulleys allowing infinitely variable gear ratios. Rather than the pulled rubber drive belts as used by DAF, the modern transmission is made much more durable by the use of steel link belts that are pushed by their pulleys. This update was pioneered by Fiat, Ford and Van Doorne in the Netherlands from the 1980s. The gearbox is also under electronic control. The CVT is available in cars such as Audi
Audi
Audi AG is a German automobile manufacturer, from supermini to crossover SUVs in various body styles and price ranges that are marketed under the Audi brand , positioned as the premium brand within the Volkswagen Group....

, Honda
Honda
is a Japanese public multinational corporation primarily known as a manufacturer of automobiles and motorcycles.Honda has been the world's largest motorcycle manufacturer since 1959, as well as the world's largest manufacturer of internal combustion engines measured by volume, producing more than...

 and the MINI ONE and MINI Cooper. Tata Motors
Tata Motors
Tata Motors Limited is an Indian multinational automotive corporation headquartered in Mumbai, India. Part of the Tata Group, it was formerly known as TELCO...

 from India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, recently announced that it too would use a Variomatic transmission in its $2500 Nano
Tata Nano
The Tata Nano is an inexpensive, rear-engined, four-passenger city car built by the Indian company Tata Motors and is aimed primarily at the Indian domestic market....

.
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