Shaft Torsion Calculation
Shaft Torsion Calculation
(OP)
I am looking for a formula to calculate shaft diameter needed.
The shaft is 20 feet long with one end stationary with no load and the other end has a 6500 in/lb load @90deg. I am looking for the angular deflection at the loaded end to determine the proper shaft diameter needed.
Thanks for your help.
Fred
The shaft is 20 feet long with one end stationary with no load and the other end has a 6500 in/lb load @90deg. I am looking for the angular deflection at the loaded end to determine the proper shaft diameter needed.
Thanks for your help.
Fred





RE: Shaft Torsion Calculation
Dr Lemaster's Lecture at UT.
http://ww
RE: Shaft Torsion Calculation
θ = TL/GJ
where
θ = shaft angular deflection in radians
T = applied torque in N·m
L = shaft length in m
G = shear modulus in N/m2 (steel is 80·109
J = polar moment in m4 (J = π·r4/2 for a solid cylinder)
If you solve for radius r, you get about 12 mm; thus, your shaft diameter should be about 24 mm, or about 1 inch.
Regards,
Cory
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RE: Shaft Torsion Calculation
RE: Shaft Torsion Calculation
RE: Shaft Torsion Calculation
The equation I provided is correct. If T, L, and G are fixed, then you must increase J (which really is only r multiplied by a constant) to result in the smallest deflection. Your choice of shaft (2-7/16 in) results in an angle much smaller than one degree.
Regards,
Cory
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
RE: Shaft Torsion Calculation
RE: Shaft Torsion Calculation
RE: Shaft Torsion Calculation
My application requires me to turn the shaft at one end (very low, 18 rpm) with a gearbox to turn a sprocket at the other end to lift 6500 in/lbs. The shaft is anchored along its length with 5 pillow block bearings to support it. Two of the pillow blocks will be mounted very close to the ends. Under a static load, I am looking for as little shaft "twist" as possible. The shaft will see little to no shock load and the gearbox will be driven with a drive to start/stop it slowly.
RE: Shaft Torsion Calculation
You'll have to be a bit careful lining up all these bearings.