Machine Drawing

Assembly Drawings 271

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d:\N-Design\Des18-1.pm5

Five piston rings 4 are positioned in the piston 1; four at the top and one at the bottom. The

top piston rings, known as compression rings, prevent leakage of gases from combustion chamber

into the crank case. The bottom one; oil or scraper ring, prevents the lubricating oil from entering

the combustion chamber.

The piston is connected to the small end of the connecting rod, by means of the gudgeon or

piston pin 2; the axial movement of which is prevented by piston plugs 3.

Exercise

Assemble the parts of the piston, shown in Fig. 18.6 and draw the following views:

(i) Sectional view from the front,

(ii) Half sectional view from the left, and

(iii) Sectional view from above.

50

3

2

(^7263)
R6

4

2

7

R190

R6

f 74

f 85

f 92

15

18

12

9

25°

10

22

15

34

15

1

2.5 10°

f^73 f^30 f^22 f

78

47

77

2 × 45°

f^11

15

f^22

12

3

45° 3

3

f 85

f 93 4

f^22

f

11

2

88

No. Name Matl Qty

1

2

3

4

Piston

Piston pin

Piston pin plug

Piston ring

Al-alloy

HCS

HCS

Cl

1

1

2

5

Parts list

7

Fig. 18.6 Piston of a petrol engine

18.2.7 Radial Engine Sub-assembly

Radial engines are mainly used for aircraft applications and are air-cooled type. The radial engine

employs a master connecting rod to which other connecting (articulated) rods are attached radially.