Electrical Motor

Тема 18. Уход за моторами

"Electrical motor"

Exercise 1. (Read the text)

The principle of the electric motor is the reverse of the gener­ator. The current travels from the battery through the field coils to one of the brushes, which allows the electricity to flow to one segment of commutator. Then electricity flows through the armature and out the other segment and brush.

The armature or rotating part and field magnets becoming elec­tromagnets, their poles are attracted to make the armature revolve. The brushes then slide on the simple commutator to break the cir­cuit. The armature poles are not now attracted to the field poles because they lost their magnetism. The armature rolls on around and again brushes complete the circuit' to attract the commutator to the second set of field magnets.

The "timing" or the arrangement of the brushes so that they make and break the. contacts on the commutator at the proper time is very important.

There are many ways of winding and connecting armature coils. Motors are made with varied speed. For example, the vacuum-cleaner motor runs at several thousand r.p.m. (revolutions per minute), and the usual washing machine motor runs at about 1725 r.p.m.

Exercise 2. (Translate the Text).

Exercise 3. (Retell the Text.)

The Text: The Care of Motors

The only care, which is needed for home electrical motors, is to see that the bearings are properly oiled. The bearings are the supports for the two ends of the armature shaft which permit the shaft to turn.

Many recently built motors have sealed bearings. It means bear­ings are so constructed that they never need oiling. But look for an oil hole on each bearing of the motor in your home. Many new appliances are provided with instructions, which tell how often to lubricate the bearings and how many drops of oil to apply.

Too much oil may cause as much trouble as no oil. Oil may penetrate into the commutator and brushes. Too much oil may soften the insulation on the wires and also collect dust to prevent air cir­culation, thus causing the motor to heat.

Don't forget about brushes. Carbon blocks held by springs against the commutator are typical brushes, when the carbon wears out, new ones must be installed. Installing brushes on many motors is not a difficult job.

Exercises:

II. Read the text and render it in English.

III. Translate the sentences paying attention to the words un­derlined.

1. Current starts flowing at the very moment when we close the circuit.

2. He was sent for as he was the only one to help us in this case.

3. At present the only thing for you to do is to work systematically.

4. Electrical conductors of the same substance, but different di­ameters have the same conductivity.

5. Tungsten is the very metal we use in the manufacture of elec­tric lamps.

6. The Ural mountains are very rich in minerals.

7. Not only metals can be used in electrical engineering.

8. This glass rod has the same kind of electric charge.

9. Amber is not the only substance that attracts light objects.

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