Well after 4month pause in super m restoration I'm back at it. I've been going to ask since spring. As much power as this tractor has can anyone tell me why all the torque to the drivetrain and pto is delivered through two 3/8"? bolts in the yoke behind the clutch. Honestly just seems like they would sheer off. They must be some good ones.
- Thread starter Goodman
- Start date
Janicholson
Well-known Member
The bolts really hold the tapered components together, they hold the stress. It does look like a committee decision. I would have preferred a flange joint with spacer, but nobody asked me. Jim
End with nuts if kept tight fit in yoke with no movement. End of bolt with rubber and washers on each side of coupling can wear. See coupling worn into bolt diameter a good bit sometimes. Have seen some 3/16 or a little more in on one side of bolt without breaking. Coupling holes also wear.
mattofvinings
Member
Each 3/8" bolt has a cross sectional area of around .1105 sq inches, total of .221 sq inches between the two of them.
Grade 5 fasteners are around 125ksi tensile. In shear it should take somewhere north of 27,000 lbs of force to shear them both.
If the bolts run on a 5" circle or a 2.5" radius from centerline (I don't know, have never measured), then it should take ~5700 lbs applied on 12" radius to shear the bolts. (That 5700 ft-lbs is more than the Super M engine can deliver most likely ). Some safety factors for impact loads, the Gr5 bolts aren't all the same, the bolts don't look to be in pure shear with the rubber isolators, etc.
But I think the design is reasonable from an engineering perspective. :shock:
Grade 5 fasteners are around 125ksi tensile. In shear it should take somewhere north of 27,000 lbs of force to shear them both.
If the bolts run on a 5" circle or a 2.5" radius from centerline (I don't know, have never measured), then it should take ~5700 lbs applied on 12" radius to shear the bolts. (That 5700 ft-lbs is more than the Super M engine can deliver most likely ). Some safety factors for impact loads, the Gr5 bolts aren't all the same, the bolts don't look to be in pure shear with the rubber isolators, etc.
But I think the design is reasonable from an engineering perspective. :shock:
Thanks Matt. I too am aware of those calculations. Just interesting to me the massive steel these designers put in the rear of this tractor in
gears and such to come down to a yoke there. Apparently no one has problems.
Your point about them not being in perfect sheer position made me wonder too. That apparent offset with a washer would make their strength
less.
Thanks. Always good discussions on here.
gears and such to come down to a yoke there. Apparently no one has problems.
Your point about them not being in perfect sheer position made me wonder too. That apparent offset with a washer would make their strength
less.
Thanks. Always good discussions on here.
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