Principal standard bearing types

T he selection of the type of rolling-contact bearing depends upon many considerations, as evidenced by the numerous types available. Furthermore, each Fig.2 Bearing standard series.

basic type of bearing is furnished in several standard ‘‘series’’ as illustrated in Fig.2. Although the bore is the same, the outside diameter, width, and ball size are progressively larger. The result is that a wide range of load-carrying capacity is available for a given size shaft, thus giving designers considerable flexibility in selecting standard-size interchangeable bearings. Some of the more common bearings are illustrated below and their characteristics described briefly.

Fig. 3

BEARING CLOSURES

Rolling-element bearings are made with a wide variety of closures. Basically, they are open, shielded, or sealed (Figs. 3). Shielded bearings have a small clearance between the stationary shield and rotating ring. This provides reasonable exclusion of dirt without an Fig. 3 Fig. 4 increase in friction. Sealed bearings have a flexible lip (usually synthetic rubber) in contact with the inner ring. Friction is increased, but more effective retention of lubricant and exclusion of dirt is obtained. Seals should not be used to seal a fluid head or at high speeds.

NOTES:

rolling element – тіло/ елемент кочення	width – ширина
bearing – підшипник	raceways – кільце підшипника кочення, напрямна
lubricant – змащувальний матеріал	cages – сепаратор
support – опора,	closures – перемичка, перегородка
figure – число, розрахунок	sealed element – ущільнюючий елемент
retainer – сепаратор підшипника

T hat’s how we express agreement and disagreement in English. Study this table.

HOW TO EXPRESS AGREEMENT AND DISAGREEMENT: Yes, it is / does. No, it isn’t / doesn’t. Certainly. Certainly not. I quite agree with you. No, you are wrong. You are quite right. You are mistaken. I’m afraid. I think so. Far from it. I can’t but agree with you. I disagree. Absolutely right. I can’t agree with you.

Task 4. Answer the following questions:

1. What is rolling-contact bearing?

2. What parts of bearing can you name?

3. What is the main function of a cage in bearing?

4. A wide variety of rolling-contact bearings are normally manufactured to standard boundary dimensions and tolerances, aren't they?

5. What is a closure? Where can it be used?

6. There is a wide variety of closures. Name them.

7. Each basic type of bearing is furnished in several standard ‘‘series’’, isn't it?

8. Sealed bearing has a rigid synthetic lip, hasn't it?

Task 5. Write 5 different type questions to the text. Ask your groupmate to answer them.

Task 6. Match the pictures and terms in column A with their definitions in column B.

	A		B
1	Single-Row Radial	A	This bearing provides for heavy radial and light thrust loads without increasing the OD of the bearing. It is approximately 60 to 80 percent wider than a comparable single-row bearing. Because of the filling slot, thrust loads must be light.
2	Maximum Capacity	B	These bearings are designed to support combined radial and thrust loads or heavy thrust loads depending on the contact-angle magnitude. Bearings having large contact angles can support heavier thrust loads.
3	D ouble-Row	C	This type of bearing is used for linear motions on hardened shafts (Rockwell C 58 to 64). Some types can be used for linear and rotary motion.
4	Internal Self-Aligning Double-Row	D	This bearing is often referred to as the deep groove or conrad bearing. Available in many variations - single or double shields or seals. Normally used for radial and thrust loads (maximum two-thirds of radial).
5	Angular-Contact Bearings	E	They may be mounted in pairs ( back-toback, tandem, or face-to-face) Tse bearings (ABEC-7 or ABEC-9) may be preloaded to minimize axial movement and deflection of the shaft.
6	D uplex bearings	F	The geometry is similar to that of a deep-groove bearing except for a filling slot. This slot allows more balls in the complement and thus will carry heavier radial loads. However, because of the filling slot, the thrust capacity in both directions is reduced drastically.
7	B all Bushings	G	This bearing may be used for primarily radial loads where self-alignment (64°) is required. The self-aligning feature should not be abused, as excessive misalignment or thrust load (10 percent of radial) causes early failure.

Task 7. Fill in the gaps using the words from the box below. Use each word only once.

requires system considered rotational selection

Basically, three common situations may be encountered in the analysis of a bearing 1)________; bearing-size 2)__________, bearing-type selection, and bearing-life determination. Each of these problems 3)_____________ the following conditions to be known; radial load, thrust load, and speed. The static load capacity is not 4)__________ in the following procedures but should be analyzed if the bearing 5)_________ speed is slow or if the bearing is idle for a period of time.

Task 8. Put these words into the right word order, make sentences and translate them into Ukrainian:

1) The most common / a locknut / best method of / a shaft shoulder /is / fit against / bearing retention / secured with / and / a press .

2) to the shaft:/ and / common methods/ eccentric locking collar/ attach the bearing/ are used to setscrew,/ Three / taper-sleeve adapter.

3) of the lubricant / of the bearing/ cause heating/ and accelerate / will / the deterioration/ Excess lubricant.

4) interchangeability/ All bearing manufacturers/conform to /these standards, /thereby permitting.

Task 9. Fill in the table using the information from the text:

Part	Function	Materials
RINGS
	They are used to space the rolling elements from each other.
		Ceramics, plastics etc.

Task 10. Translate the following sentences into Ukrainian:

1. Normally the rolling elements, balls or rollers, are made of the same material and finished like the rings. 2. Ball bearings function on theoretical point contact and they are suited for higher speeds and lighter loads than roller bearings. 3. Roller bearings are generally more expensive except in larger sizes. 4. Since roller bearings function theoretically on line contact, they will carry heavy loads, including shock, more satisfactorily, but are limited in speed. 5. The empirical X and Y factors in Eq. 3 depend upon the geometry, loads, and bearing type. 6. Sealed bearings have a flexible lip (usually synthetic rubber) in contact with the inner ring. 7. Friction is increased, but more effective retention of lubricant and exclusion of dirt is obtained.

Task 11. Imagine that you are a lecturer at the university and you should explain the first-year students the main functions of a bearing and its principle of operation. Try to make your report easy to understand. Write your report using 120-150 words. The following opening phrases may help you:

On the one/other hand … On the whole … As a matter of fact … Fortunately … So …anyway … Luckily …

In any case ... Unfortunately … By the way …

Actually … You know … You see …