Support of a heavy iron yoke

[drodrig]

Hi everybody

We are reusing an old iron yoke for a new experiment. It is ca 100t heavy. By looking at its support I was held with four big shoulder bolt type (one in each corner); which go in horizontal position. Bearing the load in shearing (I don't know if it a preloaded bolt).

I attach some pictures and design captures to show it better.

Can anybody think of a reason why it was not supported from the bottom but with these bolts? There is even a gap at the bottom

thanks

 

[BrianE22]

Is the bottom flat? The mating surface? Supporting it by the sides and assuming there's some clearance in the bolt holes , you'd be able to keep it from rocking on a non-flat surface.

 

[dhengr]

Drodrig:
It’s supported that way because that’s the way the original equipment manufacturer designed it. That isn’t the way I would do it. I would sooner shim at the (a slightly larger) gap, so I was supporting the load in bearing. That’s a more certain and direct load path, where I can also level the equip. in the shimming process. Then apply the four bolts to hold the equipment in position, and any tolerance problems btwn. bolt holes is less a problem.. Note that it appears that the equip. is supported in bearing at the foot of the angle shaped, unpainted, bearing foot bracket with the stiffener. But, the load must go through the bolt, in shear and bolt bearing on several holes before it gets to the bearing foot bracket. Also note, that with a moving piece of equip., rotating, starting and stopping, punching, impulse loads, whatever, the two bolts on one end or on one side, may each take more than 25% of the 100 ton load. I just don’t like single bolts (one each corner) for this type of connection. There is no redundancy if everything doesn’t line up perfectly or if the equip. moves a bit. On the other hand, if it has worked that way for years, replacing it in-kind has some merit too, as long as nothing else has changed.

 

[EdStainless]

Is it actually resting on the second step/shoulder on the bottom edges (mid-way between the bolts and the very bottom)?
I have seen old equipment with similar mounting, they said that it was done so that the base surfaces did not have to be precisely flat.
Sometimes you can rely on gravity to keep things held down.

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P.E. Metallurgy, Plymouth Tube

 

[drodrig]

BrianE22,
yes, the surfaces are flat, but what you say makes sense

dhengr,
I didn't really get your point, you mean you will also hold the whole weight with the "four horizontal bolts in shearing" but shimming before the whole thing to find the holes? The bolts are 60mm-2.4inches in diameter

EdStainless,
very good point! it is actually supported there right now, to move the big thing around (with air pads), but in the final position it goes with the -four horizontal bolts in shearing"

thanks all

 

[kingnero]

Thanks for the clear question with pictures, this really makes it doable to produce a decent answer.
As said above, this is not a common way to set equipment, however truth be told I haven't even come close to anything of that scale.
But to me it does not look like those four bolts hold up that piece of equipment. Perhaps there's a gap below, but I would really think it rests elsewhere.
For a M60 bolt, the anchor point with the gusset plate seems light, very light.
The "bolt" looks like all-thread, which isn't usually used in shear. It would imply that the whole thing is held in place by friction.

I don't buy it. I'd wager a bet that we don't see the whole picture.

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http://be.linkedin.com/in/fusionpoint

 

[drodrig]

Thanks kingnero,
Do you mean that the screw is preloaded?
I'll ask in order to see if this is the only support. There are so many things around that it is difficult to see
thanks