The modified wheel tractor represents the monoaxial motor module of the basic T-25A1 tractor in the unit with the active semi-trailer. For readjustment of a basic agricultural tractor in the monoaxial module from it the forward bridge with wheels, the steering mechanism and transfer details of the steering mechanism is removed. Back driving wheels of a tractor move forward by turn of final drives that provides the best distribution of loads of wheels of a tractor and the semi-trailer.
There are transmissions with mechanical, hydraulic and electric drives, but in pure form two last transfers usually are not applied. Along with electric and hydraulic units in these transmissions there are also mechanical transfers. Therefore transmissions are subdivided on:
At the same time hydrodynamic transfers possess a number of essential shortcomings: the lowered maximum value of efficiency and considerable decrease it at change of operating modes that leads to fuel consumption increase; the complicated transmission design in general because of introduction of the additional unit (the hydrotransformer; ensuring cooling with working liquid and, as a result, increase of cost of the car.
Electric transfers find application generally by cars of big power. At the low powers they turn out reweighted and have low efficiency. Electromechanical transmissions of direct and alternating current are applied. Electromechanical transmissions have advantages:
Recently much attention is paid to works on creation of domestic wheel cars. It is necessary to develop and introduce these cars in production. Creation and introduction of wheel tractors and forest cars on their base will tease to reduce park of tractors, to improve working conditions of workers, to save material and fuel and energy resources, due to decrease in metal consumption of designs, increase of their traction characteristics and decrease in specific fuel consumption on unit of the prepared (transported) wood.
Foreign cars surpass domestic analogs in many indicators: it and technical characteristics, and on convenience of service and repair, on comfortableness of work of the operator, and on many other indicators. Also abroad the wide range of logging cars from which it is possible to choose cars, applicable for these conditions of production is issued. However the developed domestic designs of forest cars not in many respects concede to foreign samples, and rather low cost and low operational costs do these cars competitive in comparison with import equipment of a similar class. Also at further service foreign cars cost much more dearer, than domestic samples as on purchase of spare parts very big expenses are required.
Essential shortcomings of mechanical transmissions: step regulation of transfer number, a rupture of a power stream and shock loadings at gear shiftings; difficulty of management; complexity of configuration by multidriving cars.
In all countries with the developed logging industry the wheel timber industry tractors equipped with various processing equipment found broad application. It is possible to refer existence of hydromechanical transmissions, the electrohydrooperated transmissions, winches with a hydraulic actuator to advantages of foreign forest wheel tractors, cabins of the operators providing safe and comfortable working conditions.
Hydromechanical transmissions turn on hydraulic and mechanical converters of a torque. In practice of autotractor construction distribution was gained by hydromechanical transmissions with hydromechanical transformers, thus perhaps consecutive and their parallel connection with mechanical part of transmission.
The main advantages of the designed car are: minimum harmful effects on soil, high speed of the movement, maneuverability, low operational costs, technological effectiveness and universality, and also some other advantages.
In this degree project the lesotransportny car on the basis of the agricultural tractor T-25A Designed Lesotransportny Car is developed represents the monoaxial motor module of a basic tractor in the unit with the active semi-trailer.