Text 1 machine-building

All sorts of machines, mechanisms, machine-tools, instruments and apparatuses are produced in the Russian machine-building industry. Every year Russia produces many types and kinds of machines, including giant turbo-generators and high-precision machine-tools, the latest foundry equipment and automatic devices, powerful building machinery, and high-precision instruments, electronic computers and atomic reactors.

The equipment for the enterprises constructed in our country and abroad is manufactured at large, first-rate plants of Russia.

On high technical level of production achieved by Russian machine-builders, our country co-operates with Poland, Rumania, Bulgaria, India and other countries in the construction of machine-building plants, producing steam turbines, boilers, piping and pipe fittings, passenger and lorries, agricultural machinery, tractors, machine-pools, tools, etc. All enterprises constructed abroad with Russian aid are successfully operating and not only reach their rated output, but, as a rule, exceed it.

In a short article such as this, it is impossible lo give even a brief description of all the types of factories and plants being built in our country and abroad. We can say that in recent years hundreds of industrial enterprises were being built in such branches as electronics, and radio engineering, communications, building materials and wood-working, light, food, chemical and pharmaceutical industries, cinema apparatus industry, etc.

Text 2 machine elements (2071)

A machine is a device for changing the magnitude, the direction and the acting point of a force for our convenience. It may thus be anything from such an elementary machine as a wedge or a lever to a 80,000 HP system turbine. In practice, however, such simple machines as wedges, levers, inclined planes or pulleys are not spoken of as machines, this name being reserved for instruments consisting of many elements.

There is an enormous number of different machines, such as printing machines, machine tools, sewing machines, combustion engines, refrigerators, etc. Although each of this consists of different parts and elements, there are some machine elements that are common to most machines.

Every machine has a frame on which the other parts are mounted and the method of joining these parts to each other is more or less the same in all machines. Two pieces of metal can be joined into one piece by welding them together, which is done by either gas welding or electric welding. The latter may be accomplished by resistance or arc welding. A bolted joint is achieved by means of nuts and bolts. A bolt consists of the head and the shank with the thread. The latter is formed by many turns which fit into the turns of the nut. Another method of making a firm joint is riveting; rivets are used in the process. Screws are mostly used when working with wood.

Many parts of a machine are mobile. A shaft, for instance, rotates about its axis, and in order to make this motion possible, it is mounted in bearings such as journal, thrust or collar bearings. Ball bearings and rolled bearings are, of course, preferable, since they reduce friction and require less lubrication. If we want to connect two shafts together, we couple them. Some well known couplings are flange coupling and the sleeve or muff. If the two shafts are not permanently coupled to each other, but can be made to engage and disengage, the coupling is called a clutch. Jaw clutches are widely used, but friction clutches are also used where the shafts require to be connected while running. Wheels are mounted on shafts by means of keys (saddle keys, flat keys, sunk keys, etc.).

If the teeth of one gear wheel engage those of another, they are said to be geared to each other and the arrangement is called a gear. The five important types of gears are the spur gear, the helical gear, the spiral gear, the bevel gear and the worm, which engages a worm-wheel; a rack is usually in mesh with a pinion. Pulleys are geared to each other by belts.