Bearings

A bearing is a machine part which supports shafts and spindles. We know bearings to be classified as plain bearings and antifriction bearings.

In plain bearings one friction side slides upon another. Plain bearings may be of two classes: bearings witn a continuous rotary motion and those with an intermittent motion. The first class of plain bearings is represented by journal bearings and thrust bearings. Journal bearings are bearings carrying a load which acts at right angles to the shaft axis. Thruct bearings take a load acting in the direction of the shaft axis. The second class of plain bearings embraces bearings of parts having a rocking motion or a linear reciprocating motion.

Antifriction bearings are also subdivided in two main classes: ball bearings and roller bearings. In rotating machines, noise and vibration are indications of faulty operation of ball bearings or roller bearings. A ball bearing consists of two rings: an inner ring and an outer ring between which there are hardened steel balls spaced in a ball ratainer or cage. In rotating machines, the balls are spaced so that they do not touch each other, thus reducing wear and noise. They require an ab- solutely parallel raceway to roll upon.

Ball bearings may be of the following types: radial bearings, thrust bearings and redial thrust bearings. In their turn radial ball bearings , may be of two types: single-row and double-row radial bearings. All the radial bearings are used when high speeds are required. The precisiorn-made radial bearings give the finist service together with a long bearing life. Thrust ball bearings are bearings taking axial loads and giving maximum efficiency with combined journal and thrust loads. Radial ball bearings can take both radial and axial loads.

In roller bearings hardened steel rollers are used between the rings instead of balls. Roller bearings permit a larger load and have a longer bearings life in comparison with ball bearings. The rollers used in roller bearings may be of different shape. Roller bearings may be subdivided into single-row and double-row bearings.

ІІІ. Language.

Ex.7. Match word and word combinations in column A with those in column B:

Column A	Column B
bearing load rotation faulty operation thrust bearing ring raceway hardened steel intermittent motion concave	загартованна сталь кільце підшипник оборот зіпсована робота навантаження стійкий підшипник періодичний рух угнутий бігова доріжка підшипника

Ex.8. Match words and their definitions:

A bearing is A ball bearing is Plain bearings Radial ball bearings Thrust bearings

consists of two rings: an inner ring and outer ring. a machine part which supports shafts and spindles may be of two classes: bearings with a continuous rotary motion and those with an intermittent motion take a load acting in the direction of the shaft axes may be of two types: single-row and double-row radial bearings

Ex.9. Find the right ending of the sentences and translate these sentences:

8. In plain bearings … ………… .

1. steel balls spare spaced in a cage.

2. one friction surface slides upon another.

3. there are two rings.

1. Journal bearings ………………………. .

1. carry a load which acts at right angles to the shaft axis.

2. to transmit a varying angular velocity either continuously or for a portion of revolution.

3. embrace bearings of parts having a rocking motion.

1. Ball bearing may be ………………. .

1. of two main classes depending upon the type of rolling elements.

2. classified as plain bearing and antifriction bearings.

3. of the following types: radial bearings, thrust bearing and radial-thrust bearings.

1. All the radial bearings ……………. .

1. reduce wear and noise.

2. are used when high speeds are required.

3. require an absolutely parallel raceway to roll upon.

1. Roller bearings ………………….. .

1. permit a larger load and have a longer veering life.

2. give the finest service together with a long bearing life.

3. Give maximum efficiency with combined journal and thrust load.

Ex. 10. Fill in the blanks using the following words:

1. spaced, b) supports, c) wear, d) noise, e) consists, f) antifriction bearing, g) roller bearings, h) retainer, i) ball bearing, j) plain bearings, k) intermittent motion, l) rotary motion, m)thrust bearing.

1. A bearing is a machine which …….. shafts and spindles.

2. We know bearings to be classified as ………….. and ……….. .

3. Plain bearings may be of two classes: bearings with a continuous ……….. and those with an …………. .

4. …………….. take a load acting in the direction of the shaft axis.

5. ………….. are also subdivided into two main classes: …………. and ………. .

6. A ball bearing ……….. of two rings: an inner ring and an outer ring between which there are hardened steel balls spaced in ……………….. .

7. In rotating machines, the balls are ………….. that they do not touch each other, thus reducing …….. and ………… .