Machine Design Miscellaneous
 In order to test the efficiency of reducer gear train 1 kW input was given at the input end at a speed of 1440 rpm and at the output end the measured torque was 56.36 Nm. If the ratio of speed reduction in this unit is 10: 1, the efficiency is about

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Speed reduction = 10: 1
Output speed = 1440 = 144 rpm 10 Output Torque = T.ω = 56.36 × 2π × 144 = 849.88 N  m 60 % efficiency = Output × 100 Input = 849.88 × 100 = 85 %(Approximately) 1000 Correct Option: B
Speed reduction = 10: 1
Output speed = 1440 = 144 rpm 10 Output Torque = T.ω = 56.36 × 2π × 144 = 849.88 N  m 60 % efficiency = Output × 100 Input = 849.88 × 100 = 85 %(Approximately) 1000
 Which of the bearings given below SHOULD NOT be subjected to a thrust load?

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NA
Correct Option: C
NA
 A horizontal plate has been joined to a vertical to a vertical post using four rivets arranged as shown in the figure. The magnitude of the load on the worst loaded rivet (in N) is _______.

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Primary force (P_{1}) = 100 N
P"_{1 } = P"_{2} = P"_{3} = P"_{4} = P_{e} × r 4r² = 400 × 500 × 40√2 2 4 × 40√2 2
= P"_{1} = 1767.766N
1 & 4 are worst loaded
∴ (P_{net})² = (P_{1})² + (P"_{2})² + 2(P_{1})(P"_{1}) cos 45°
P_{net} = 1839.83 NCorrect Option: C
Primary force (P_{1}) = 100 N
P"_{1 } = P"_{2} = P"_{3} = P"_{4} = P_{e} × r 4r² = 400 × 500 × 40√2 2 4 × 40√2 2
= P"_{1} = 1767.766N
1 & 4 are worst loaded
∴ (P_{net})² = (P_{1})² + (P"_{2})² + 2(P_{1})(P"_{1}) cos 45°
P_{net} = 1839.83 N
Direction: A single riveted lap Joint of two similar plates as shown in the figure below has the following geometrical and material details.
width of the plate ω = 200 mm, thickness of the plate t = 5 mm, number of rivets n = 3, diameter of the rivet d_{r} = 10 mm, diameter of the rivet hole d_{r}= 11 M mm, allowable tensile stress of the plate σ_{p} = 200 MPa, allowable shear stress of the rivet σ_{s} = 100 MPa and allowable bearing stress of the rivet σ_{c} = 150 MPa.
 If the rivets are to be designed to avoid crushing failure, the maximum permissible load P in kN is

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For rivet,
σ P = P 3A_{r} 3d × t
∴ P_{s} = 100 × d × t × 3 = 15 kN
and P_{c} = 150 × d × t × 3 = 22.5 kN
∴ p = max (15, 22.5) = 22.5 kNCorrect Option: C
For rivet,
σ P = P 3A_{r} 3d × t
∴ P_{s} = 100 × d × t × 3 = 15 kN
and P_{c} = 150 × d × t × 3 = 22.5 kN
∴ p = max (15, 22.5) = 22.5 kN
 A cylindrical shaft is subjected to an alternating stress of 100 MPa. Fatigue strength to sustain 1000 cycles is 490 MPa. If the corrected endurance strength is 70 MPa, estimated shaft life will be

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By concept of straight line,y  1.8451 = 1.8451  2.6902 x  6 6  3
At y = 2
⇒ x = 5.4501
log10_{N} = 5.4501, N = 281914Correct Option: C
By concept of straight line,y  1.8451 = 1.8451  2.6902 x  6 6  3
At y = 2
⇒ x = 5.4501
log10_{N} = 5.4501, N = 281914