In belt drive design, if the velocity ratio is 3:1 and the smaller pulley has a diameter of 100 mm, what should be the diameter of the larger pulley?
Answer: B
Velocity ratio = D₂/D₁ = N₁/N₂. Therefore, 3 = D₂/100, giving D₂ = 300 mm
Q.42Medium
A cast iron flywheel has a mean diameter of 800 mm and rotates at 600 RPM. If the allowable tensile stress is 60 MPa, what is the maximum thickness of the rim?
Answer: B
Using the formula for rim thickness: t = (ρ × v²)/(σ_allowable), where v = π × D × N/60 = 25.13 m/s, and ρ for cast iron ≈ 7200 kg/m³, t ≈ 25 mm
Q.43Medium
Which type of key is most suitable for transmitting high torque in rotating shafts with frequent load reversals?
Answer: B
Woodruff keys provide better shock resistance and are less likely to loosen under load reversals due to their semi-circular design and secure seating.
Q.44Medium
A riveted joint connecting two steel plates has 6 rivets arranged in two rows. If each rivet has a diameter of 16 mm and the tensile stress in the joint is 120 MPa, what is the tensile load on the joint?
In spur gear design, the module is 4 mm and the number of teeth on the pinion and gear are 20 and 60 respectively. What is the center distance between the gears?
Answer: B
Center distance = (m × (T₁ + T₂))/2 = (4 × (20 + 60))/2 = 160 mm
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Q.46Medium
A rolling contact bearing has an equivalent dynamic load of 8 kN and a rating life of 10,000 hours at 1500 RPM. Which bearing parameter is most affected by speed and load combination?
Answer: B
The L10 life (in revolutions) is directly affected by both the equivalent dynamic load and speed according to the bearing life equation: L₁₀ = (C/P)³ × 10⁶
Q.47Medium
Which of the following statements is TRUE regarding stress concentration in machine design?
Answer: C
At lower speeds (static loading), stress concentration has more severe effects as fatigue is not a factor and stress peaks can cause immediate failure. Larger fillet radii reduce stress concentration.
Q.48Medium
In a multi-plate clutch, if there are 5 pairs of friction surfaces and the coefficient of friction is 0.3, what is the relationship between the torque transmitted and the axial force?
Answer: C
T = μ × F × r × n, where n = number of friction surfaces = 5 × 2 = 10. Therefore, T = 0.3 × F × r × 10 = 3.0 × F × r
Q.49Hard
A spring is subjected to a tensile stress of 600 MPa. If the endurance limit of the spring material is 400 MPa and the stress concentration factor is 1.8, what is the factor of safety against fatigue?
Answer: B
Corrected endurance limit = 1400.8 = 222.2 MPa. Factor of safety = 222.6002 = 0.37. However, using the safe stress (endurance limit)/operating stress correctly: FOS = 400/(600 × 1.8/actual calculation) ≈ 1.11
Q.50Easy
Which of the following materials is BEST suited for manufacturing hydraulic cylinder pistons?
Answer: C
Stainless steel provides excellent corrosion resistance, high strength, and better sealing properties in hydraulic applications compared to other options.
Q.51Easy
In a worm gear drive with a single-start worm, module 2 mm, and 40 teeth on the gear, what is the worm pitch?
Answer: A
For a worm gear, pitch = module × number of starts = 2 × 1 = 2 mm (for a single-start worm)
Q.52Medium
A deep groove ball bearing is subjected to a radial load of 5 kN and an axial load of 2 kN. If the X and Y factors for this bearing are 0.56 and 1.8 respectively, what is the equivalent dynamic load?
Answer: C
Equivalent dynamic load P = X × Fr + Y × Fa = 0.56 × 5 + 1.8 × 2 = 2.8 + 3.6 = 6.4 kN (approximate)
Q.53Medium
In brake design, which factor is MOST critical when designing brakes for automotive applications operating at high temperatures?
Answer: A
High-temperature brake operation requires materials with excellent thermal conductivity to dissipate heat quickly, preventing brake fade and maintaining friction coefficient stability.
Q.54Easy
A hollow shaft has an outer diameter of 60 mm and inner diameter of 40 mm. What is the polar moment of inertia of the shaft?
In a power screw design, if the pitch is 5 mm, major diameter is 20 mm, and the coefficient of friction is 0.15, what is the efficiency of the screw?
Answer: B
Using η = (l - μπd_m)/(l + μπd_m) where l = 5 mm, μ = 0.15, and d_m ≈ 18 mm, efficiency ≈ 35.8%
Q.56Easy
Which type of bearing is preferred for applications requiring self-alignment capability?
Answer: B
Spherical roller bearings have a spherical outer raceway that allows self-alignment up to 2-3 degrees, making them ideal for misaligned shaft applications.
Q.57Medium
A V-belt drive operates with a belt velocity of 20 m/s and transmits 30 kW. If the belt has a mass of 0.5 kg/m, what is the centrifugal tension in the belt?
Answer: D
Centrifugal tension T_c = m × v² = 0.5 × 20² = 200 N
Q.58Hard
In gear tooth bending stress analysis according to Lewis equation, which parameter does NOT directly affect the bending stress?
Answer: A
Pitch line velocity affects dynamic load factors but the Lewis equation σ = (P_t × Pd)/(F × Y) directly depends on transmitted load, diametral pitch, face width, and form factor, not pitch velocity.
Q.59Medium
A clutch is designed to transmit 15 kW at 1500 rpm. If the coefficient of friction is 0.3 and the axial force is 2000 N, what is the effective radius of the clutch disc?
Answer: B
Using P = 2πNT/60 and T = μ × F × r_e, solving gives r_e ≈ 95 mm for the given parameters.
Q.60Easy
In a spur gear design, what is the primary function of backlash?
Answer: B
Backlash is intentionally provided to accommodate thermal expansion, manufacturing errors, and to prevent gear jamming.
