VARIANTS OF TWO-COUPLE GEAR SHIFTING ORGANIZATION ON TRACTORS

In recent years, we can see trend of increasing tractor transport and operating speeds, which is also accompanied by increasing of gears number in manual transmissions. Increasing of gears number in Powershift transmissions is achieved by using in gearbox construction a few operating ranges. Every range and every gear of such gearboxes are switched by separate friction clutch that gives opportunity to organize gear shifting without power interruption in all tractor speed range. However, such technical solutions lead to appearing gear shifting, requiring of pressure control in four friction clutches at once (two-couple gear shifting): two gear clutches and two range clutches. This article is dedicated to the questions of two-couple gear shifting process organization in agricultural tractor gearboxes. These questions had required to design mathematical model of this process in Matlab Simulink software. Modelling was implemented under conditions that transmission control system and engine control system had opportunity of data exchange between themselves, which allowed to define the load torque value, acting on engine, and to control engine speed. A few variants of two-couple gear shifting up and down organization were modelled and compared in parameters of clutch wear. The modelling results show that simultaneous high gear clutch and high range clutch slipping during gear shifting gives the same oncoming clutches accelerated synchronization as during gear shifting with engine control.

tractor, gearbox, control system, gear shifting, engine control, friction clutch