What is the Lewis form factor for a 20° involute spur gear with 25 teeth?
Answer: B
Using Lewis form factor tables for 20° involute gears, Y ≈ 0.295 for 25 teeth.
Q.242Easy
A journal bearing is subjected to a radial load of 10 kN with shaft speed of 600 rpm. If bearing length is 80 mm and shaft diameter is 50 mm, find the bearing pressure (Hertzian pressure approximation).
In a screw-jack with pitch 8 mm and mean diameter 40 mm, if the efficiency is 25%, what is the mechanical advantage?
Answer: C
M.A. = π × d_m / p × (1/efficiency) = (π × 840) × 4 ≈ 47.1.
Q.244Easy
What is the primary advantage of using roller bearings over ball bearings in heavy industrial applications?
Answer: B
Roller bearings have larger contact area and can sustain higher radial loads compared to ball bearings.
Q.245Medium
A wire rope with diameter 16 mm has a tensile strength of 1770 MPa. Calculate the breaking load if the rope has 6×19 construction (core factor = 0.55).
In a sliding contact bearing, which parameter represents the bearing characteristic number?
Answer: A
The Sommerfeld number λ = μN/P is the primary bearing characteristic number used in hydrodynamic bearing analysis.
Q.247Hard
A cone clutch has cone angle 15°, outer radius 150 mm, inner radius 100 mm, and coefficient of friction 0.25. Find the torque capacity for 3000 N axial force.
Which type of gear arrangement is suitable for power transmission between skew axes?
Answer: C
Worm and worm gear drives are specifically designed for non-parallel, non-intersecting skew axes with large speed reduction.
Q.254Medium
In a chain drive with sprocket teeth numbers N₁ = 20 and N₂ = 60, chain pitch = 12.7 mm, speed of motor shaft = 1500 rpm, find the linear chain velocity.
