Gearbox shaft design
Preliminary diameter d ≥ ∛(T·10³/(0.2[τ])), [τ] = 10…20 MPa; mesh forces; reactions in two planes; moment diagrams M = √(Mv² + Mh²); fatigue s = sσ·sτ/√(sσ² + sτ²) ≥ [s].
Shaft calculator: support reactions, moment diagrams, diameter and safety factor
Enter the torque, gear diameter and distances — the calculator finds mesh forces and reactions, draws bending moment diagrams in two planes and the torque diagram and checks fatigue under the gear and the bearing.
FAQ
How are shaft moment diagrams built?
Find reactions in two planes, compute bending moments at load points, combine them geometrically and plot the torque separately.
How is the preliminary diameter found?
d ≥ ∛(T·10³/(0.2[τ])) with [τ] = 10…20 MPa, rounded to standard.
What safety factor is required?
Usually 1.5…2.1; 1.3…1.5 with an accurate design model.
Where is the critical section?
Where bending is high and there is a stress raiser: under the gear (keyway) and at the bearing with an overhung load.
How is the coupling force considered?
F ≈ 125√T (N, T in N·m), directed to increase stresses.