Identified content errors were corrected on 2026-10-25. Sources and scope for this page: University of Florida — Keys and couplings (accessed 2026-10-25), covering torque-based key shear and bearing checks. Standard dimensions alone do not establish load capacity. What the 2026-10-25 correction changed is stated with the source above; nothing beyond that scope was re-checked. How sources, methods and updates are recorded.
Last updated 2026-10-25
How the joint carries torque
A keyed joint transmits torque through contact between a separate key, shaft keyseat and hub keyway. A spline uses mating teeth. Neither construction guarantees overload protection, and both require stress and fit checks.
Shaft diameter helps select a standard key cross-section. Design torque, load history, key length, materials and engagement determine whether its shear and bearing capacities are adequate. A key is not automatically a mechanical fuse.
Choose a joint for the actual load
Splines can provide multiple contact surfaces and may allow axial sliding when designed for it, but load sharing is not automatically uniform. Tooth geometry, fit, fatigue, alignment and manufacturing constraints matter. Use a deliberately designed overload device when a predictable release torque is required.
Basis and scope
University of Florida — Keys and couplings: Torque-based key shear and bearing checks. Standard dimensions alone do not establish load capacity.