Machine design Basics - I - Shaft, Bearings & Gears

Explore press fits and interference fits for mounting bearings and components on shafts, and learn how shaft-hub tolerances and friction govern holding power and assembly strength.

Analyze deflection and slope of a centrally loaded simply supported shaft by deriving slope and deflection diagrams from the bending moment diagram, and check against bearing tolerances and gear misalignment.

Learn how to select bearings for shafts, from plain bushings to fluid and rolling contact bearings, balancing space, loads, speed, lubrication, life, and misalignment in design.

Explore the factors driving bearing selection in machine design, including loads, speed, packaging, life, friction, lubrication and sealing, tolerances, assembly, temperature, contamination, materials, and misalignment.

Identify the primary causes of bearing failure, focusing on metal fatigue due to contact stresses at ball/roller–race interfaces, and the role of contamination, lubrication, misalignment, corrosion, and manufacturing defects.

Explain contact stresses at curved surfaces, forming hemispherical pressure distributions and the maximum B max in ball bearings and roller contacts, and how larger contact areas reduce stress.

Determine the equivalent bearing load by combining radial and axial components using VFR criteria. Extract X, Y, and C_not values from manufacturer catalogs to compute P.

Assess the maximum axial load the bearing can tolerate and compute the minimum radial load with the formula, applying preloading when the radial load falls short.

Explain the conjugate action of gearing, where two gears maintain a constant velocity ratio via rolling contact along a fixed line of action at the pitch point.

Learn how to compute the contact ratio by analyzing the contact angle, angle of approach, and angle of recess, using addendum circles, line of action, and length of engagement.

Explore worm gearset design basics for high gear ratios and sliding contact. Learn lead angle, axial pitch, circular transverse pitch, starts, and the worm gear pitch diameter.

Design a worm gearset in CAD using Indian values, determining the reference diameter, axial pitch, and lead angle to create the worm profile and sweep it for proper engagement.

Execute the worm gearset design workflow in CAD part 3 by using addendum circle profiles, extruding, and circular patterning around the cylinder axis, then compute the twist angle for sweep.

perform spur gear force analysis by calculating transmitted load from 1 kW at 1000 rpm with a 200-tooth gear and determine gear reactions via pressure angle and force triangle.

explain bevel gear force analysis by deriving the average radius RTV from the gear cone geometry and relating the tangential force W.T to RTV and the cone angle Delta.

Explains gear surface damage from high contact stresses using Hudson contact mechanics, modeling teeth as cylinders to compute max contact pressure from local radii of curvature and material properties.