Machine Drawing

Bearings 187

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d:\N-Design\Des12-1.pm5

15 22

M52f

58

15 15

f

16

8 1015 30 15 10

300

335

30 28

2

f

60

60°

(^2542)

2 2 2 2

f

38

f

64 f

85

f

35

f

f 42

62

f M 100

118

f

(^124) f^45
Fig. 12.17 Revolving center

THEORY QUESTIONS

12.1 What is a bearing and what is meant by journal?

12.2 How are bearings classified?

12.3 Name the different forms of journal bearings.

12.4 Under what conditions, a pedastal bearing is preferred?

12.5 Name the various parts of a plummer block.

12.6 How the bolts are prevented from rotation in a plummer block?

12.7 What are the commonly used bearing materials?

12.8 Why collars are provided at the sides of bearings brasses?

12.9 What is a snug? What is the function of it in the bearing?

12.10 Why countersunk hole is provided at the top of the body of the bearing?

12.11 Why elongated holes are generally provided in the base of a bearing?

12.12 Why is the base of the bearing generally kept hollow at the bottom?

12.13 Why a disc is provided at the shaft end in a pivot bearing?

12.14 Distinguish between:

(a) sliding contact bearings and anti-friction bearings,

(b) bracket and hanger bearings,

(c) pivot bearing and collar bearing, and

(d) journal bearing and thrust bearing.

12.15 What is a rolling contact bearing?

12.16 Why are rolling contact bearings called anti-friction bearings?

12.17 What are the different shapes of the rolling elements used in anti-friction bearings?

12.18 Explain the specification of a bearing 205.

DRAWING EXERCISES

12.1 Draw (a) half sectional view from the front, with left half in section and (b) view from above of a

bushed bearing, suitable for supporting a shaft of diameter 25mm.