Browsing by Subject "traktori"

The history of tractor in Finland is 100 years old and in the whole world 120 years old. Development of tractors is continually ongoing. During the first decades it concentrated on engines. The introduction of air-filled tyres made it possible to increase speed on the road, which in turn lead to an increase in the number of gears. Most of the inventions within transmissions were made during the 1950s. The first powershift gears, stepless hydrostatic transmissions, fuell-sell tractor, range-gear and the power shuttle were all introduced during this time. Over the next decades these features were improved and presented as new inventions. The hydrostatic-mechanical power split continuously variable transmission (CVT) has become more common in recent years, but the basic invention was already in use elsewhere during the 1910s. The first CVT tractor was the Fendt 926, which was launched in 1995. Later introductions came in 1999, when ZF’s Eccom and the S-Matic both came to the market. Of all the CVT tractors that were introduced to the market up until 2008, only the John Deere IVT ant the Valtra Direct machines were equipped with the manufacturer’s own diesel engines and CVT transmissions. All other CVT tractors were manufactured using five different transmissions and engines. In the coming years, several more transmissions and brands will appear on the market. Mechanical Torotraks and steel belt variators will be available for low-horsepower tractors in the sub-75 kW class. At the same time the number of brands seen in the CVT arena is increasing and the differences in the construction of stepless transmissions will grow. Current CVT transmissions differ from each greatly, with different functional principles, functionality and structure. Transmissions are divided into two main categories on the basis on functional principle, either summing up torque or summing up speed. The functionality division in mostly based on the hydrostatic part. In a full-CVT transmission, the percentage decrease of hydrostatic transmission has s linear relationship with the percentage increase in running speed. The function of the hydrostat in a semi-CVT transmission in to balance the speed differences between different gearing rations. In these transmissions the hydrostatic part of the transmission in around 20–40%. The percentage of hydrostatic transmission in double-CVT transmission varies with the driving speed. Double-CVT transmissions can have several driving speeds where the percentage of mechanical transmission is very close to 100%. The theoretical predictions about how common new features will become is based upon a study of four-wheel tractors in Western Europe and Finland. This can be precisely calculated using Logistic-funktion the result would be better if the source data covered a longer time period. The regular S-curve depicts how common the new features will become in tractors of the future. The real growth area is during the period when the market share of 4wd tractors increase from 10 to 90 %. This shows that the annual growth in Western Europe was 4,0% and in Finland 7,5%. Within the next few years it will become necessary to study further new entrants of the CVT transmission market and to make predictions more precise by means of increasing the amount of source data. The users driving with conventional transmissions could utilise the driving strategies of CVT transmissions. Tractor manufacturers should ensure that their customers are fully educated in the use of their new machines, in order that they develop the correct driving habits. This in an important part of postmarketing strategy.