Machine Design Miscellaneous
Direction: A 20° full depth involute spur pinion of 4 mm module and 21 teeth is to transmit 15 kW at 960 rpm. Its face width is 25 mm.
 The tangential force transmitted (in N) is

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P =15 kW
m = 4 mm
Z_{p} = 21
N = 960 rpm
b = 25mm
D_{p} =mZ_{p} = 4 × 21 = 84 mmSpeed of pinion, υ = πD_{p}N m / s 60000 = π × 84 × 960 = 4.22 m / s 60000
Also, P = F_{t}υor F_{t} = P = 15 × 1000 υ 4.22
≈ 3552 NCorrect Option: A
P =15 kW
m = 4 mm
Z_{p} = 21
N = 960 rpm
b = 25mm
D_{p} =mZ_{p} = 4 × 21 = 84 mmSpeed of pinion, υ = πD_{p}N m / s 60000 = π × 84 × 960 = 4.22 m / s 60000
Also, P = F_{t}υor F_{t} = P = 15 × 1000 υ 4.22
≈ 3552 N
 A spur pinion of pitch diameter 50 mm rotates at 200 rad/s and transmits 3 kW power. The pressure angle of the tooth of the pinion is 20°. Assuming that only one pair of the teeth is in contact, the total force (in Newton) exerted by a tooth of the pinion on the tooth on a mating gear is ________.

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NA
Correct Option: A
NA
 Two mating spur gears have 40 and 120 teeth respectively. The pinion rotates at 1200 rpm and transmits a torque of 20 N.m. The torque transmitted by gear is

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We know
N_{p} = T_{G} N_{G} T_{p}
where,
N_{p} = speed of pinion,
N_{G} = speed of gear wheel
T_{G} = number of teeth of gear,
T_{p} = number of teeth of pinion∴ 1200 = 120 N_{G} 40
or N_{G} =400 r.p.m.
Since power transmitted by both gear will be equal
i.e. T_{p}ω_{p} = T_{G}ω_{G}
where,
T_{p} = torque transmited by pinion
T_{G} = torque transmitted by gear wheel∴ 20 × 2π × 1200 = T_{G} × 2π × 400 60 60
∴ Torque transmitted by gear, T_{G} = 60 Nm.
Correct Option: D
We know
N_{p} = T_{G} N_{G} T_{p}
where,
N_{p} = speed of pinion,
N_{G} = speed of gear wheel
T_{G} = number of teeth of gear,
T_{p} = number of teeth of pinion∴ 1200 = 120 N_{G} 40
or N_{G} =400 r.p.m.
Since power transmitted by both gear will be equal
i.e. T_{p}ω_{p} = T_{G}ω_{G}
where,
T_{p} = torque transmited by pinion
T_{G} = torque transmitted by gear wheel∴ 20 × 2π × 1200 = T_{G} × 2π × 400 60 60
∴ Torque transmitted by gear, T_{G} = 60 Nm.
 A wire rope is designated as 6 x 19 standard hoisting. The numbers 6 × 19 represent

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NA
Correct Option: C
NA
 A singleplate clutch has a friction disc with inner and outer radii of 20 mm and 40 mm, respectively. The friction lining in the disc is made in such a way that the coefficient of friction μ varies radially as μ = 0.01 r, where r is in mm. The clutch needs to transmit a friction torque of 18.85 kN mm. As per uniform pressure theory, the pressure (in MPa) on the disc is __________.

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Correct Option: A