1/2" Carriage Bolt Loading?

[tomrscott]

1/2\" Carriage Bolt Loading?

This should be simple for someone out there. I can probably find this somewhere, but off hand don't know where.

My JD790 rear R4 wheels have four 1/2" carriage bolt holes (square holes) for mounting wheel weights. I'm wondering what the load capacity of those carriage bolts are? I'd like to put about 500 lbs of homebrew wheel weights on them, but the JD owners manual doesn't say what the limit is. They say you can mount up to 3 of their cast iron wheel weights per wheel. The tractor manual doesn't say what their weights weigh, but they don't ever really say that the limit is the strength of the wheel or bolts. It may just be how long the bolts they supply are. Could also be an excess of caution over liability issues with as nutty as their lawyers have gotten.

Seems to me, just my mechanical intuition, those bolts ought to handle about 500 pounds each (~2.5 x my weight?). The wheel rim face is 3/8" thick steel. With four bolts, seems like 500 lbs per wheel ought to be safe? /forums/images/graemlins/ooo.gif

 

[bobodu]

Re: 1/2\" Carriage Bolt Loading?

If in doubt...buy grade 8s.. /forums/images/graemlins/grin.gif

 

[ThistleKop]

Re: 1/2\" Carriage Bolt Loading?

<font color="blue">If in doubt...buy grade 8s </font>

Bobodu, They may be grade 8. He did not say what they are. That is a very relevant point. Can be determined by looking at the marking on the head of the bolts.

TK

 

[Soundguy]

Re: 1/2\" Carriage Bolt Loading?

Sure.. just straight load.. it would take quite a bit to have a failure on even a grade 2 bolt. Side loading and shear, and shock loading all effect that. However.. with 4 holes per wheel.. I'd guess you can bolt on as much weight as the tractor can handle with (4) 1/2" carriage bolts. if in doubt.. use grade 5 or 8. I'd guess 4 grade 8 bolts would carry as much weight than a scut tractor axle will be rated for. when you count both rears and even fronts.. etc..

Soundguy

 

[PILOON]

Re: 1/2\" Carriage Bolt Loading?

As far as I know, carriage bolts would not be available in the higher grades, like 8.
Only ones I have ever seen are the hardware store variety mild steel.

On the other hand 4 ea 1/2 bolts can take a lot of wt.

My concern would be the fact that in this application they would be in shear and also they will tend to wander and possibly wear through.

As suggested better to use grade 8 or better regular machine bolts and washers even if you have to get a helper to hold a spanner on the other side.

Probability is that JD have graded special PN's for that application.

My 2 cents.

 

[justforme]

Re: 1/2\" Carriage Bolt Loading?

mcmaster.com

has grade 5 carriage bolts listed on there site

additionally they have 8.8's if you need something in metric

 

[tomrscott]

Re: 1/2\" Carriage Bolt Loading?

I am surprised that carriage bolts are available in grade 5, but that is good to know, thanks!

Another consideration: I would rather the bolts snap than the wheel face get deformed at all if this is going to be pushing it, but I am really having a tough time imagining that it can be a problem. Still, maybe I am better off using cheap carriage bolts. The are surely not better steel than the wheel face, and if something is going to give, they'll shear and I'll know pretty quick. It's not like it is going to be a major catastrophe if a wheel weight starts clattering on two or three bolts cause one or two sheared off.

The weights I am making are out of 3/8" plate, about 20 pounds each, easy enough to handle one at a time.

I got to thinking that I have put my whole 200+ lbs of weight on a single cheap grade 1/4" lag bolt without snapping it. The more I think about it, I think even the lowest grade 1/2" bolts would probably each hold the 500 lbs, with four I am having a hard time getting worried about it.

If the wheel face were thinner material, I might worry about it deforming, but 3/8" plate is pretty stout. I am sure a John Deere wheel is good quality steel.

 

[Soundguy]

Re: 1/2\" Carriage Bolt Loading?

</font><font color="blue" class="small">( As far as I know, carriage bolts would not be available in the higher grades, like 8.
)</font>

The specialty fastener store that the GC I work for buys from can get just about any type of bolt.. any grade.. any material... and yes.. we have bought hard carriage bolts.

</font><font color="blue" class="small">( this application they would be in shear )</font>

My concern as well.

I think I would find some pipe to cut and use as a bushing or spacer.. and add a few large flat washers to that, and size the weights mount holes for those pipe sections. Either way.. 4 bolts are gonna hold alot of weight.. no matter what grade.

Soundguy

 

[mrcaptainbob]

Re: 1/2\" Carriage Bolt Loading?

I agree with that, Soundguy. Four 1/2" grade 5 bolts would hold a lot. Heck, that's only 125# per! I don't think, however, that these are really in shear and that the chance of the weight hanging from a couple on one side (should two adjacent actually break!) would stand a bigger chance of rim distortion by the time the last two gave way. I don't think any of that would really happen though.

 

[JJT]

Re: 1/2\" Carriage Bolt Loading?

No problems with the bolts and the load. Anybody see a problem with 500#'s per wheel on a JD790? Seems excessive to me. My larger Kubota only has 400#'s per wheel and that's CACL.