Shafts, Keys & Couplings
Every shafts, keys & couplings calculator on CalcEngines — each with its formula, a worked example, the standard it follows and the assumptions it makes.
7 calculators in this section
- Coupling Torque and Selection CalculatorSelection torque for a flexible coupling from power, speed and a published service factor — then checked against what the prime mover can actually deliver, which for an induction motor is usually the larger number. With misalignment allowances by coupling type, the rule that they cannot all be used at once, and the bearing reaction the coupling puts back into the shaft.
- Interference Fit and Shrink Fit CalculatorA hollow hub on a solid or hollow shaft in two different materials, by the Lamé thick-wall equations: contact pressure, torque capacity, push-out force, hub hoop stress and the assembly temperature — computed at BOTH ends of the ISO 286 interference range, with the roughness the surfaces lose on assembly subtracted the way DIN 7190 does it.
- Parallel Key and Keyway Dimensions CalculatorKey width, height and both keyway depths to DIN 6885-1 and ISO 773 from the shaft diameter, with BOTH depth conventions printed side by side, the real clearance or interference each fit class delivers computed from the ISO 286 bands, Woodruff keys as a separate family, and the hub wall left over the keyway.
- Shaft Critical Speed CalculatorFirst bending critical speed of a shaft, bracketed between Dunkerley's lower bound and Rayleigh's upper one, with the shaft's own distributed mass, up to two point masses and three support conditions that differ by a factor of six — plus what the published codes actually require for separation margin, which is not the 75% everyone quotes.
- Shaft Deflection and Slope CalculatorDeflection AND the slope at the bearing, for the standard shaft load cases, checked against the published misalignment limits for what is actually at the bearing — because misalignment is what kills bearings, not deflection. The stepped-shaft case is solved exactly by Castigliano and the usual equivalent-diameter answer printed beside it.
- Shaft Fillet and Stress Concentration CalculatorKt for the three stress raisers that matter on a shaft — a shoulder fillet, a circumferential groove and a keyway — from published closed-form fits with their sources and their uncertainty named, plus the notch sensitivity that turns Kt into the fatigue-effective Kf. The chart of Kt against fillet radius is the point of the page.
- Spline Torque Capacity CalculatorTorque capacity of an involute or straight-sided spline against all three published limits — tooth shear, flank compressive stress and torsional shear of the shaft under the teeth — with the smallest governing, the fraction of teeth actually carrying as an input, Dudley's load distribution factor, and the factor of nine between a fixed and a flexible spline.