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Up Topic Welding Industry / General Welding Discussion / Fastening Down Welders to Your Truck
- - By welderbrent (*****) Date 08-18-2014 13:34
Guys,

Based upon the recent event I would like to suggest some caution:

1) Please do fasten down your welders to your truck.
2) Do your research, there is a reason hitch suppliers provide Grade 5 bolts for installation of their hitches.  Grade 8's are better for higher torque, But Grade 5's are better when shear is involved.  You have the same forces at work with your welder as a hitch.  Forward and backward shear.  The machine is not being used to pick up the whole truck and it's weight keeps one from needing down pressure nearly as much as resisting the shear.
3) One might consider, but I don't know if this is accurate, structural bolts instead.  Grade A325. 
4) Safety is always a major consideration.
5) We never like saying good bye from preventable accidents. 

He Is In Control, Have a Great Day,  Brent
Parent - - By Plasma56 (**) Date 08-20-2014 00:31
Hi Brent,

While I agree with your caution regarding the need for fastening welders to truck decks, I suggest and feel any bolts is better than none at all for this purpose.  It was preventable but at the same time, what are the odds? What scares me more is the slide in skids.

I do however question your comments regarding bolts in #2. I was under the impression that a grade 8 bolt surpassed a grade 5 bolt in all mechanical properties? Could you explain this further to clarify the point.
My google search suggest grade 5 and A 325 are the same? I was however always spending the extra for grade 8 bolts so I need convincing.
As you mentioned, safety and prevention should be the concideration.

At the very least, 4 small 1/4" fillets, 1 inch long = 70psi. The guy was a welder. Lets not forget that mute point.
Parent - - By welderbrent (*****) Date 08-20-2014 02:44
The problem comes from the way you stated the hypothesis: "I was under the impression that a grade 8 bolt surpassed a grade 5 bolt in all mechanical properties?" 

So, when we look at "all mechanical properties" where do we start?  The most basic is tensile strength of the bolt?  Sure, Grade 8 surpasses Grade 5.  Clamping force?  Yes 8 passes 5.  Shear strength?  UUMM.  Do we need to define that to specify does it have a higher point of shear or higher probability to shear?  Look at what happens with any of your steels as the tensile strength goes up.  They become more brittle.  They will shear where the Grade 5 will yield and hold. 

We used Grade 8's on farm equipment where we wanted shear because when it went it sheared cleaner and was easy to remove compared to the Grade 5 which would hold too long and allow for damage to parts and when it did shear it didn't snap clean and was often a pain to remove so it could be replaced. 

Years ago people we hunted with started putting Grade 8's in to hold their hitches on their trucks.  It was soon discovered that the grade 8's would snap too easy under hard braking or an accident and the next thing you knew the trailer was going down the road by itself.  Ask hitch manufacturer's why their engineers design the units for and include Grade 5's in the hitch installation kits. 

Now, those are my personal experiences and research on the differences between Grade 5 and 8.  I am not an engineer.  I stated that everyone should do their own research.  Don't take my word for it.  Who knows?  I could be all wet.  Oh, I am.  4 1/2" in just a few hours here this morning.  Major flooding in the valley of the Sun Worshippers.  Rained all night at my place in Prescott but we didn't even get 2".  They had the snow plows out clearing the mud off the interstate and side roads. 

Just my two tin pennies worth on the bolts.  And while Grade 5 and A325 are BASICALLY the same, they are not the same.  Structural bolts are regulated, tested, and in other ways superior to machine bolts.  Are they better for hitches OR welders?  Don't know.  Just a suggestion to check and see. 

I agree with the comment about even some small welds.  The main point was, FASTEN DOWN YOUR WELDERS.  Even if recessed into a pocket so they don't NORMALLY slide, they aren't safe unless fastened down. 

He Is In Control, Have a Great Day,  Brent
Parent - By Plasma56 (**) Date 08-20-2014 05:43
Hi Brent,

I'm not an engineer either friend, just trying to make sense of stuff to form an opinion I can call my own with a degree of confidence and understanding to support it. Two guys talking. Lots more listening.

Tragically, the image of the forces present when that welder came loose hit close to home. I hit the ditch in a similar fashion in a company service rig, my welder was however bolted down, and while the welder held on tight, the capped bottles came loose in there clamping. The outcome not as serious or tragic as the young man who lost his life.

When I fastened down my Ranger 9 years later back in the day to my truck bed, they were 3/8 grade 5 bolts no doubt in my mind. Grade 8's cost to much.  Large washers on the underside due to the risk of pulling out after the scare. But I wasn't thinking mechanical properties either?
Between us, I think 4 , 3/8"  grade 5 bolts were called for minimum. Frame had 4 - 3/8" holes and the manual said to mount securely. They didn't however say much more. I do use grade 8 bolts in my tow bar without any issues, pivot points, receiver location and mounting hardware. I didn't cheap out there thinking I had a greater risk of liability to be responsible for protecting against when transporting car projects on the cheap. My bolt guy said use grade 8's.

At the end of the day, what matters most is the message of ensuring personal and public safety by securing the welder to the transport.
The conversation that results is the education of understanding it would you think?

Higher point of shear and probability of shear now has me thinking so to gain understanding, satisfy the listeners, the higher point of shear would be related to tensile strength?
Higher probability of shear would be related to hardness? Are we thinking alike?

I could see where the grade 5 while yielding at a lower applied force, could be ductile enough to stretch over the limit in duration a higher strain is being applied. Is that a dazzel of brilliance or flawed thinking?
Hows that for a sentence? Did it make any sense? Sometimes I'm not sure if I'm trying to convince myself or confuse myself? I would think when looking at loading it would be a shock to the fastener.
However, I'm not sure I accept your way of thinking brittleness in this useage? I just wouldn't describe a grade 8 bolt as being more brittle, harder maybe? Tougher? I just wouldn't have used brittle.

I did however do a quick google search on this grade 5 grade 8 topic.
And your right on when you say, bolt them down.
Grade 8 is seemingly like insurance, more is better. But a grade 5 is enough in most cases.   Internet can't be wrong right?

Just after reading your post, pictures flashed over the evening news. I caught the news report, more rain forecasted. Major flooding and wash outs... Prayers are with you folks.
- - By Northweldor (***) Date 08-20-2014 12:59
In the welder vs hitch example, the shear forces are much more perpendicular to the bolts on the hitch. And, in my experience with farm equipment, the shear was most often between two rotating parts like a gear or flywheel and axle, also perpendicular.

In addition, what about torque and friction? If sufficient torque is applied to grade 8 bolts, friction will lock the parts together, and shear force is eliminated, and tensile strength is more important. I think we need an engineering opinion, and, since the top-heavy welder will tend to rotate around the front side bolts, I think I would go for grade 8 in the meantime:confused::confused:.
Parent - - By welderbrent (*****) Date 08-20-2014 16:29
One great advantage is the way I see a lot of welders put on trucks that are pretty well permanent attachments for working- recessed into the bed in some way.  Then for sure it is only a matter of some clamping force to keep them from bouncing or being thrown out in an accident. 

As to the comments about clamping force removing the shear, or at least reducing it, I see that.

Remember, none of my comments is as an engineer only as a concerned fellow welder turned enemy, I mean inspector, and wanting to see everyone get home to their family at the end of the day.  Anything used is better than nothing in this case.

Let's not use this to run a topic to death, an extreme apology for the choice of word, Just be safe guys.  A little bit of prevention goes a long way. 

Back to the farm, Freeman baler with large flywheel taking the energy from the PTO on the 125-150 horse power tractor and going around at a pretty good clip.  When either a foreign object or a large wad of the windrow went into the bale chute if things weren't just right it needed to shear the bolt to keep from breaking other things.  It was also a safety so that if the timing was off when the baler went through the cycle that brought the 'needles' up and tied either wire or twine to make a bale, you wanted the bolt to shear to keep from having the plunger that compacts the hay into the chute hit and break the needles and other mechanisms.  You needed the right clamping force, shear strength, and ability to get a clean break so it was easy to remove and replace.

He Is In Control, Have a Great Day,  Brent
Parent - - By Cumminsguy71 (*****) Date 08-25-2014 19:35 Edited 08-30-2014 14:26
post edited.....

plain and simply put,

common sense
Parent - By Tommyjoking (****) Date 08-28-2014 01:22
Good post BUMP
Parent - By rcwelding (***) Date 08-30-2014 21:56
Thank you Shawn.
Up Topic Welding Industry / General Welding Discussion / Fastening Down Welders to Your Truck

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