Page 26 - WCS - Electrical

a
a
b

b

7
1
7
=
=
2
:

7
1
2
=
=
14 =
:
7
2
: 1
2
14
c
a
=
a
d
b
=
d
b
b
a
b
a
c
d
=
c
d
d
b
=
b
d
a
c
=
c
a
d
b
a +
=
=
c +
d
a +
d
b
b
a +
c
c
a
b
=
c
c
b
b
d
c −
a −
=
d
b
a −
c −
d
=
b
c
a +
b
a
=
=
a +
c
a
b
c
d
b +
d
=
=
d
d
b +
c
3
6
=
6

3
8
4
=
4 14 = c b = 14 c + d and and a : 1 a + = b c + c + d
8
3 4
3 4 = WORKSHOP CALCULATION & SCIENCE - CITS
= 6 8
6 8
4 8
• 4 = 3 8 = 6
3 6
• 3 + 4 6 + 8
=
3 + 4 6 + 8
8 8
3 4 − = 4 6 −
4 = 8 60 = Rs.30
=

• 3 − 4 4 = 6 − 8 8 60 2
4 8 = 2 = Rs.30
• 3 + 6 = 9 = 3
3 + 84 + 6 = 9 12 = 3 4 x = 50 × 30 = 10teeth
50
4 + 8 12 4 x = 180 × 30 = 10teeth
Ratio - relation of two quantities of the same kind.
Proportion - equality between two ratios.
180
1
Example x = 70 × 2.5 = 25days
1 20

2.5
70 × 7
• A steel plate of 800 x 1400 mm is to be drawn to a scale of 1:20. What will be the lengths in the Fig 1.
25days
x =
=
20 7
1 Δh = 1
800 × 1 20 = 40mm Δh l = 1 20
800 × = 40mm l 20
20
1
1400 × 1 20 = 70mm 3 − 4 6 − 8 60
1400 × = 70mm = = = Rs.30
20 4 8
3 − 4 6 − 8 2
400 T = 60 = Rs.30
=
= 4 8 2
6
300
400 T 24 3 + 3 − 4 9 6 3 8− 60
=
=
= = = = Rs.30
50
300 24 4 + 8 4 12 3 + 4 8 9 3 x = × 2 30 = 10teeth
6
24 × 400 4 + 8 = 12 = 4 180 50
T = 24 × 300 = 32Teeth 3 + 6 9 3 x = × 30 = 10teeth
400
T = = 32Teeth 1 = = 180
50
The reduction ratio is . 84 + 12 4 x = = 70 × 2.5 = 10teeth
300
25days
30 =
×
x
120 20 1 180 7
30gallons/
day
=
B is reduced from 800 to 800 x = 40 mm. 70 × 2.5
120 4 20 Δh 1 x = = 25days
= 30gallons/ day 1 1 = 7
=
2.5
800 ×
40mm
4 L is reduced from 1400 x = 70 mm. l x = 70 × Δh = 25days
20
20
1
20

7
1
=
=
40mm
800 ×
20
• Find the number of teeth of the larger gear in the gear transmission shown in the Fig 2.
l
20

1

1400 × = 1 70mm Δh = 1
800 × = 40mm
20
20 1 l 20
1400 × 20 = 70mm

400 T 1
1400 = 70mm
= ×
300 24 20
400 T
=
24 × 400 300 24
400
T
T = = = 32Teeth
300 300 24
24 × 400
T = = 32Teeth
120 24 × 400 300
=
day
T = 30gallons/ = 32Teeth
4 300
120
= 30gallons/ day
4
120
= 30gallons/ day
4
13
CITS : WCS - Electrical - Exercise 2