Bearings, shafts, keys, couplings, gears, belts, chains, springs, fasteners, seals, clutches, brakes, and flywheels — how engineers actually select and size the components a drivetrain is built from.
A catalog page will tell you a bearing's bore, a gear's pitch, or a bolt's grade — it won't tell you which one actually belongs in your design. This module goes past the catalog: how a shaft's diameter comes from combined torque and bending, why a properly preloaded bolt is designed to carry almost none of the external shear load directly, why gear backlash is a deliberate tradeoff and not a manufacturing defect, and why fatigue at a stress concentration — not a single overload — is the failure mode that shows up again and again across nearly every element in this module.
By the end of this module you should be able to explain why a self-locking worm gear mesh trades efficiency for backdrive safety, and why torque alone is only an approximate proxy for the bolt preload that actually holds a joint together — two judgment calls Module 6's drivetrain design sequence builds on directly.