Driveshaft Critical Speed Calculator
SI
Imp
Imperial
Inputs
View results
Shaft length
(L)
Free span between effective supports.
in
Outer diameter
(OD)
Tube outside diameter.
in
Wall thickness
(t)
Tube wall thickness.
in
Elastic modulus
(E)
Young modulus of the shaft material.
Mpsi
Density
(rho)
Material density.
lb/ft³
Use-speed factor
(f)
Recommended operating speed as a fraction of calculated first critical speed.
Results
Default result
Edit inputs
Suggested max speed
(n_safe)
6,418
rpm
Pass
Using 0.75 x calculated critical speed.
Also computed
First critical speed
(n_cr)
8,557
rpm
Inner diameter
2.764
in
Tube area
1.069
in²
Second moment of area
(I)
1.112
in⁴
Mass per length
3.639
lb/ft
Method notes
2 notes
Uses a uniform simply supported tube approximation for first bending critical speed.
Real driveshaft limits also depend on joint angles, weld yokes, balance quality, tube straightness, end constraints, torque, dents and operating vibration.
Powered by MachineCalcs ↗