Calculate the diameter and length of a stub axle - dannybekaert.be

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calculate stub shaft

Calculate the required diameter d and length l of a stub shaft due to bending, surface pressure and heating in case of semi-dry friction

stub shaft

Load F on the stub shaft		N
Predetermined diameter d of the stub shaft		mm
Predetermined distance l		mm

Allowable surface pressure σ₀		N/mm²

For your information, some guidance values for σ₀
Hardened steel on hardened steel	14.7	N/mm²
Hardened steel on bronze or white metal	8.8	N/mm²
Unhardened steel on bronze or white metal	5.9	N/mm²
Cast iron on bronze	2.9	N/mm²
Steel on cast iron	2.5	N/mm²
Steel on lignum vitae	2.5	N/mm²

Allowable bending stress σ_b

N/mm²

For your information, some guidance values for σ_b
St70	58.8	N/mm²
St50	49.0	N/mm²
St41	44.1	N/mm²

Revolutions per minute n of the shaft		RPM

Factor w for the heat calculation		no unit

For your information, some guidance values for w
Gear boxes and normal stubs with ring lubrication on bronze	150000 tot 400000
Crank pins of fixed machines	400000 tot 600000
Crankshaft collar of steam engines	280000 tot 400000
Crank pins of steam engines	400000 tot 600000
Steamturbines	2300000
Crankshaft collar of combustion engines	600000
Crank pins of combustion engines	1000000
Marine machinery	600000 tot 800000
Shaft neck of passenger cars	660000 tot 950000
Shafts of locomotives	1330000 tot 1900000
External crank pins	2500000

Specific heat of the cooling oil		kJ/kg.K
ΔT that the oil is allowed to heat		K

The calculation result is:

d _{predetermined}	?	mm
According length l of the stub = d_{predetermined}.sqrt((π.σ_b)/(16.σ₀))	?	mm

Diameter d_{surface pressure} = 4.F/(π.σ₀.l_{predetermined})	?	mm
According length l of the stub = d_{surface pressure}.sqrt((π.σ_b)/(16.σ₀))	?	mm

Diameter d for bending = (16.F.l_{predetermined}/(π.σ_b))^(1/3)	?	mm
According length l of the stub = d_bending.sqrt((π.σ_b)/(16.σ₀))	?	mm

Required length l of the stub l for heat dissipation : F.n/w	?	mm
Is cooling oil required?	?
Circumferential speed of the stub = π.d_{predetermined}.n/60000	?	m/s
Friction labour = 0,05.F.v.3,6	?	kJ/h
Required cooling oil = friction labour/(specific heat cooling oil.ΔT)	?	kg/h

Enter your number values and press the Calculate! button to know the calculation result.

All calculated diameters d are for full shafts, for conversion to hollow shafts see "Properties of sections part 2".

Normal shaft diameters are: 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 125, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, 460, 480, 500 mm