![]() Today, minimisation of losses, increases in of efficiency, and improvement of transmissions are targets for both tractor manufacturers and researchers (Paoluzzi, 2007).Īlthough different authors have evaluated total losses of agricultural tractor transmissions, particularly with mechanically driven gears, specific studies have not been carried out to evaluate the causes of losses. The location of the elements in which the losses are concentrated helps minimise problems and improve transmission design (Bartz and Wienecke, 2000). These studies showed that the power losses depend on the speed of the gears, the transmitted power, the lubrication regime, the material of the transmission, and the oil temperature. In the automotive sector many theoretical and experimental studies have been conducted for identifying the causes of energy dissipation in a transmission (Greenbaum et al., 1994 Park et al., 1996 Bartz and Wienecke, 1999). In power-shift and CVT transmissions, losses can be higher (Renius and Vahlensieck, 1996). (2003), who determined power losses in a mechanical transmission. Similar results were obtained by Ryu et al. ![]() Efficiency was found to vary from 60% to 90% depending on the engine performance and operating conditions (Reiter, 1991). In recent years, research on tractor transmissions has focused on the determination of power losses. ![]() The term power-shift refers to the fact that gear shifting does not require the operator to disengage a traction clutch (Goering and Hansen, 2005). Worldwide the range of typical tractor transmissions has widened with very simple technologies adopted for tractors in developing countries, whilst multiple-gear transmissions have been adopted for typical mid-range tractors in highly industrialised markets, and closely stepped automatic transmissions have been adopted for large sophisticated tractors (Kempf, 1999).Īlthough the types of mechanical transmission available have increased, power-shifts have also proliferated, particularly in the medium-high power range and with the continuously variable transmissions (CVT) (Renius and Resch, 2005). ![]()
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