Small wind / Buyer questions
Mechanical interfaces
Do two shafts with the same nominal diameter accept the same hub?
The short answer
No. A nominal shaft diameter identifies a size, not the complete mating condition. A wind-generator hub also depends on dimensional tolerances, form, locating features and the intended torque/axial load path. Two parts marked with the same diameter may assemble differently or be unsuitable together.
Read the shaft and bore as a pair
Identify the shaft tolerance and mating-bore tolerance at the same reference temperature and section. Their possible limits determine whether clearance, transition or interference can occur. The nominal size alone leaves that relationship unresolved. A measured diameter on one sample also cannot establish the full specified production range, and an average value can conceal taper or out-of-roundness along the working seat.
Look beyond cylindrical size
Check engagement length, shoulder position, chamfer, key or spline geometry and any intended axial retention. A hub can slide onto a shaft yet bottom against the wrong feature; another can have the correct fit but insufficient engagement. For a friction-driven connection, surface condition and contact pressure are part of the approved design. For a keyed connection, the shaft/bore fit still influences centering independently of key capacity.
Request a mating-interface assessment
Ask for the controlled shaft and hub drawings, actual fit designation and a section showing how the hub is located and retained. NSK fit documentation supports distinguishing nominal dimensions from fit ranges; it does not select a MARSTON fit. Treat an envelope match as the beginning of compatibility review. The supplier should confirm the exact offered combination and its load-transfer arrangement before a replacement is accepted or any shaft, bore or keyway modification is considered. Ask whether a quoted replacement preserves the shaft’s functional locating surfaces as well as its diameter. A changed shoulder position can invalidate axial alignment even when the cylindrical fit is completely unchanged.
Sources
Examples are illustrative. Confirm product-specific performance, compatibility and supply scope in the applicable documents.