| The tractor vehicle is distinguished by a low speed and high tractive force. The tractor is widely used in agriculture to plough land and to tow non self-propelled vehicles and instruments. The tractor can be equipped with hinged and semi hinged equipment of agricultural, construction or an industrial purpose (for example, drilling equipment).
There are two basic types of tractors — roller and chain-track tractors. Both types have advantages and drawbacks.
It is possible to use a roller tractor on general-purpose roads, on which the tractors can develop high speeds. However, their track adhesion with the ground is limited and consequently, the tractive force is also limited. On friable soil, such tractors can slip. To eliminate this drawback, tractors with a drive on all wheels are created, however, such vehicles are heavy while moving on a field, and they heavily consolidate the earth. To reduce the pressure on the soil the width of the tractor tires has increased recently.
Chain track tractors possess a high tractive force, when compared to roller tractors. The main drawback of the majority of chain track tractors is the inability to move on asphalted roads without destroying the covering; the exception is for tractors with a rubber – cable chain. The low speeds of chain-track tractors (30—40 km/hr) are compensated by the reduced pressure on the ground because of the large area of contact with ground at the same weight, compared to the roller tractor. Chain-track tractors are widely used in agriculture, on weak bearing soils and in the industry due to its unpretentiousness.
Tractor components:
The main components of the tractor: engine, transmission, undercarriage, control mechanisms and working and auxiliary equipment. Without dependence on type, the diesel engine (earlier petrol engines were also used) is the power plant of modern tractors. The steering control of the roller tractors is similar to automobile steering control; one of the chains is stopped with a friction clutch so as to make a turn. Working equipment: Tractors are equipped with a hydraulic linkage, which serves for connecting the tractor with hinged and semi-hinged vehicles and works in controlling these vehicles. The hydraulic linkage consists of two main parts: the linkage device and the hydraulic system. The PTO shaft is available in many tractors, which is meant for the drive of the working organs, aggregated with tractors of mobile or stationary vehicles.
History:
For the first time, vehicles similar to tractors appeared in the 19th century and were steam vehicles. In the year 1850, English inventor William Howard used a loco mobile for ploughing the soil. In the second half of the 19th century, more than two thousand such machines were used in the fields of Great Britain. The first chain-track tractor was built in Russia by peasant Fedor Abramovich Blinov, a native of the village Nikolsky, in the district Volsky in the Saratov province. In 1879, he obtained the patent ("privilege") on the “Carriage with endless rails for the transportation of cargo on the highway and country roads”. This facility was put into operation by the steam engine with 20 hp.
In 1896, the first tractor with an internal combustion engine was created by American engineers Hart & Parr. From 1901, such tractors were put on sale. Initially, farmers willingly bought them; however, soon the new tractors were giving complaints: they were very heavy and consequently, tamping the soil heavily. The tractors were too big for an average farm. The tractors suffered with “children's illnesses”: often broke and the repair was long and as well as too costly. However, new tractor models, without the drawbacks of its predecessors, appeared for sale in 1907. By that time, repair shops for tractors were formed in America.
In 1912, firm "Holt-Parr" started manufacturing the chain-track tractors.
|
