Task 2. Translate the following sentences into Russian paying attention to the meaning of the articles where necessary.

1.The facts you have just mentioned have brought about great changes in industry. Let us consider only the changes which have been brought about by the use of electricity in chemical processes.2.Where has the new machine so much spoken about been installed? It has been installed in the plant it was built for.3.In our laboratory we deal with materials which can be withstand high temperatures. 4.This is a new radar set. The set can perform scanning of an area by beam of microwaves.5.Popov constructed an apparatus which could receive electromagnetic waves at a distance. The apparatus was approved of after having been successfully tested.

Task 3. Speak about eminent Russian inventor.

VARIANT 11

Task 1.Read and translate the text.

PRESS, SHRINK, AND FRICTION JOINTS

Definitions,- A press joint, also called a force joint, is obtained by forcing a shaft into a hole that is slightly smaller than the shaft. This is possible because of the elasticity of the materials which produces the grip that holds the hub and shaft together.

A shrink joint differs from a press joint chiefly by the method of assembling it. The hub is heated to expand its bore and to slip it on the shaft. When the hub cools down to the temperature of the shaft, the grip is produced in the same way as in the force joint. The shrink joint is also used to connect machine parts by means of special rings, anchors, and tie rods.

In a friction joint the holding grip is produced by the conical shape of the shaft end and the hub bore and by the pull of a nut, or by a slotted hub whose bore is smaller than the shaft and which is spread by a wedge when the joint is being assembled.

Comparison of Joints.-The assembling of a shaft and a hub by means of a press joint is simpler than that with a shrink joint especially if a hydraulic press of a sufficient capacity is available. Shrink joints are used mainly in places where it is difficult or impossible to assemble a press joint, as in the case of rings or anchors. On the other hand, shrink joints assemblies with the same interference as press joints give more than three times the holding power against both torsion and axial pull, This superior effectiveness is due to the absence of abrasion between the surfaces of the shaft and the hub during assembly.

All three joints are used when machine parts must be connected more securely than can be accomplished with a key or screw joint, especially when they are subjected to shock or vibration.

Дата добавления: 2015-11-14