jdkuhndog
Mechanical
- May 1, 2003
- 68
Greetings.
I have an application where a crane will be recovered in emergency situations with a 'recovery' wheel. The best design for this will utilize a splined shaft through the wheel (actually two drive wheels on either side of the crane span).
Anyhow, I was curious if I was calculating this correctly. The spline shaft and 'recovery' wheel will experience conservatively 4000#*in of Torsion.
I am planning to use 4140 Material (Su=140ksi, Sy=90ksi).
The root diameter of the spline will be: droot = 1.113". The Outside diameter of the spline will be: 1.260".
There will be 20 splines total.
There will be 4" of engagement between the spline and the wheel.
J=(pi*droot^4)/32 = 0.151 in^4
c = droot/2 = 0.557"
Tshr=T*c/J = (4000#*in)*(0.557"
/(0.151 in^4)
Tshr=14.8ksi
Allowable Shear = 140ksi/5 = 28ksi < 14.8ksi =>OK
Since I currently have no details on the spline profile, I conveniently ignored any stresses incurred at the root by the force applied to the tip of the spline - I assumed this would be minimal since the force is distributed over 4" length and over 20 teeth. Is this a horrible assumption?
Thanks for any input.
I have an application where a crane will be recovered in emergency situations with a 'recovery' wheel. The best design for this will utilize a splined shaft through the wheel (actually two drive wheels on either side of the crane span).
Anyhow, I was curious if I was calculating this correctly. The spline shaft and 'recovery' wheel will experience conservatively 4000#*in of Torsion.
I am planning to use 4140 Material (Su=140ksi, Sy=90ksi).
The root diameter of the spline will be: droot = 1.113". The Outside diameter of the spline will be: 1.260".
There will be 20 splines total.
There will be 4" of engagement between the spline and the wheel.
J=(pi*droot^4)/32 = 0.151 in^4
c = droot/2 = 0.557"
Tshr=T*c/J = (4000#*in)*(0.557"
/(0.151 in^4)Tshr=14.8ksi
Allowable Shear = 140ksi/5 = 28ksi < 14.8ksi =>OK
Since I currently have no details on the spline profile, I conveniently ignored any stresses incurred at the root by the force applied to the tip of the spline - I assumed this would be minimal since the force is distributed over 4" length and over 20 teeth. Is this a horrible assumption?
Thanks for any input.
