Mechanical engineering

It is well known that with the invention of the steam engine and the growth of factories a number of civil engineers became interested in the practical application of the science of mechanics and thermodynamics to the design of machines. The result was that they separated themselves from civil engineering and called themselves "mechanical engineers”. It was that trend that laid the foundation for a new branch of one that was called mechanical engineering.

At present mechanical engineering occupies a prominent position among modern production processes. It is mechanical engineering that deals with the design and construction of steam engines, turbines, air-conditioning and refrigeration devices. Conveyors, escalators and elevators are also designed by mechanical engineers. And again, it is the mechanical engineer that designs machine-tools for various operations and it is he who applies these machine-tools in various production processes.

One must know, too, that aeronautics is also one of the many branches of mechanical engineering, the one that deals with the mechanics of moving bodies in fluid or air.

1. What inspired interest of civil engineers to practical applications of some sciences?

2. What mechanical engineering deals with?

Задание 17. Напишите сочинение-эссе (600 знаков), в котором вы высказываете свои мысли на тему.

Scientific and technological breakthroughs have brought great benefits. You only have to look around your own home to see

Have our lives always been improved by using home machines and devices, however? Have we become too passive? Are we too dependent on technology? How dangerous could it be? Take, for example, television/computer games/the Internet .

Задание 18. Напишите аннотацию (не более 500 знаков) к тексту.

Tractor is powerful low-speed traction vehicle and power unit mechanically similar to the automobile or truck but designed for use off the road. The two main types are: wheeled (which is the earliest form) and caterpillar tractors. Tractors are used in agriculture, construction, road building and other works in the form of bulldozers, scrapers and excavators. A notable feature of tractors is power takeoff accessory, used to operate stationary or draw machinery or implements.

The first tractors grow out of stationary and portable steam engines operated at farms in the late 19^th century; they were used to haul plows by the 1890s. In 1892 a blacksmith John Froelich built the first farm vehicle powered by a gasoline engine. The first commercially successful manufacturers were Hart and Parr from Charles City, Iowa. By the World War I the tractor was well established; the American Holt tractor was the inspiration and base for the tanks.

Belt and power takeoffs, incorporated in early tractors, were standardized first in the rear-mounted, transmission-derived power takeoff, and later in the independent (live-power) takeoff, which permitted operation of implements at a constant speed regardless of the vehicular speed. Many modern tractors also have a hydraulic-power takeoff system operated by an oil pump, mounted on the tractor or on the trailer.

Most modern tractors are powered by internal combustion engines running on gasoline, kerosene, liquid petroleum gas (LPG) and diesel fuel. Power is transmitted through a propeller shaft to a gearbox having 8 or 10 speeds, and through a differential gear to the two large rear-drive wheels. The engine may have from 12 to more then 120 horsepower. Until 1932, when oversize pneumatic rubber tires with deep treads were introduced, all wheel-type farm tractors had steel tires with tapering lugs to engage the ground and provide traction.

Crawler, caterpillar or track-laying tractors run on two continuous tracks consisting of a number of plates (pads) pivoted together and joined to form a pair of endless chains, each encircling two wheels on either side of the vehicle. These tractors provide better adhesion and lower ground pressure that the wheeled tractors do. Crawler tractors may be used on heavy, sticky soil or on very light soil that provides poor grip for wheels. The main chassis usually consists of a welded steel hull containing the engine and transmission. Tractors used on ground of irregular contours have tracks mounted so that their left and right front ends go up and down independently.

Four-wheel drive tractors can be used under various soil conditions. Because of their complicated construction and high cost their use grows slower.

The single-axle tractor is a small machine carried on a pair of wheels fixed on a single-drive axle; the operator usually walks behind, gripping the pair of handles. The engine is in front of the axle, and the tools are on the bar behind. This type of machine may be used with a considerable set of equipment, including plows, hoes, cultivators, mowers and two-wheeled trailers. When the tractor is coupled with the trailer the operator rides.