# Farm Machinery Questions and Answers – Power Transmission System – 1

This set of Farm Machinery Multiple Choice Questions & Answers (MCQs) focuses on “Power Transmission System – 1”.

1. Two pulleys are connected by a belt. The sum of the diameter of two pulleys is 90 cm and while the one makes 50 rpm, the other makes 20 revolutions. What will be the diameter of the pulleys?
a) 19.7cm, 70.3 cm
b) 23.4 cm, 68.7 cm
c) 25.7 cm, 64.3 cm
d) 21.1 cm,63.2 cm

Explanation: D1 + D2 = 90cm
Or, 50 * D1 = 20 * D2
Or, D2 = 2.5 D1
Now, D1 + 2.5 D1 = 90
D1 = 25.7 cm
D2 = 64.3 cm

2. Two pulleys are connected by a belt. The sum of the diameters of the pulleys is 92.6 cm and while one makes 50 rev/min the other make 200 rev/min. What will be the diameter of the pulleys?
a) 18.53 cm, 74.07 cm
b) 19.65 cm, 64.89 cm
c) 20.01 cm, 78.09 cm
d) 17.69 cm, 69.90 cm

Explanation: D1 + D2 = 92.6 cm
D1N1 = D2N2
50(92.6 – D2) = D2 * 200
D2 = 18.53 cm
D1 = 74.07 cm

3. In which rivet joint the plates are kept in the same plane?
a) Lap joint
b) Wood screws
c) Butt joints
d) Cap screws

Explanation: Rivets are used for connecting two pieces of metal plates or bars permanently. In butt joints, the plates are kept in the same plane and the joint is covered on one or both sides by a cover plate which is riveted to the plates.

4. What is the train value (G) in compound gear train?
a) G = $$\frac{N6}{N1} = \frac{T1*T2*T3}{T2*T4*T6}$$
b) G = N6 * N1 = T1+T2+T3+T4+T6
c) G = N6 – N1 = T1 * T2 * T3 * T4 * T6
d) G = $$\frac{N1}{N6} = \frac{T2*T4*T6}{T1*T2*T3}$$

Explanation: A system of gears which transmits motion from one shaft to another is known as a gear train. When there is more than one gear on a shaft, then, it is called a compound train of gear.

5. What is the length of cross belt to connect two pulleys 4 m apart. the diameter of driving and driven pulley is 1.25 m and 0.75m respectively?
a) 12.39m
b) 11.39m
c) 13.39m
d) 10.39m

Explanation: Lc = 2x + $$\frac{π}{2}$$(d1+d2)+$$\frac{(d1+d2)^2}{4x}$$
= 2*4 + $$\frac{π}{2}$$(1.25+0.75) + $$\frac{(1.25+0.75)^2}{4*4}$$
= 11.39m.
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6. Which of the following is not a type of chain?
a) Roller
c) Pintle
d) Bevel

Explanation: Bevel is a type of gear used where the axis of the two shafts are at right angles and can intersect each other. When the power has to turn a corner, bevel gears are used. Plain bevel gears have straight teeth while spiral bevel gears have twisted teeth.

7. Which of the following is not a type of screw?
a) Machine
b) Hexagonal
c) Square
d) Plough

Explanation: Machines are a type of screws which are threaded for their full length. They look like bolts. They are used to screw directly into threaded holes in machine part and do not need nuts.

8. What is the width of belt to transmit 15 HP to a pulley 35 cm in diameter. Pulley makes 1600 rev/min, coefficient of friction between belt is 0.22 and angle of contact is 20°. Maximum tension in belt not to exceed 8 kg per cm width.
a) 7.79cm
b) 9.79cm
c) 3.49cm
d) 8.79cm

Explanation: $$\frac{T1}{T2}$$ = e0.22*3.66=e0.8065
T1 = T2 * 2.24
15*746 = $$\frac{[π*35*1600(T1-T2)]}{100*60}$$
2.24 T2-T1 = 381.63
T2 = $$\frac{381.63}{1.24}$$ = 307.76N
T1 = 307.76*2.24=689.38N
Width of the belt = $$\frac{689.38}{8*9.8}$$ = 8.79cm.

Sanfoundry Global Education & Learning Series – Farm Machinery.