Abscraperguy
Senior Member
How much is heavy equipment overbuilt to compensate for shock loads without failing? Example: if axle loads are 10000 lbs sitting still to what strength would the axle be built?
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- Thread starter Abscraperguy
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hvy 1ton
Senior Member
I can't give you any specifc numbers, but the service/saftey factor for dynamic loading is normally 1.5-2.5. I'm having bit of trouble remembering, but i think saftey factors are on top of the rating. So, a factor of 1.5 would be 250%. I'm not sure if this is true, but i've been told that most heavy equipment start with 20% over loaded as the basis.
So, 10K axle*120%(20%overload)*250%(safety factor)= 30K dynamic load rating
I didn't sleep much last night and had two tests today, so Tigerotor77W or somebody else will probably come along and correct me.
So, 10K axle*120%(20%overload)*250%(safety factor)= 30K dynamic load rating
I didn't sleep much last night and had two tests today, so Tigerotor77W or somebody else will probably come along and correct me.
special tool
Senior Member
The real question is....why do you want to know?
You have a bet with your buddy, don't you.
John C.
Senior Member
Everything I have had to deal with needed a four to one safety factor.
Hydraulic hose for instance may have a 4,000 PSI service rating and at a minimum requires a 12,000 PSI burst rating. As I recall wire rope on a crane had the same factor.
When we are putting safety cages on excavators back in the last seventies I know we figured all that at four to one also.
Good Question? I'm sure someone else will chime in.
Hydraulic hose for instance may have a 4,000 PSI service rating and at a minimum requires a 12,000 PSI burst rating. As I recall wire rope on a crane had the same factor.
When we are putting safety cages on excavators back in the last seventies I know we figured all that at four to one also.
Good Question? I'm sure someone else will chime in.
I think the most truthful answer would be that it depends upon the manufacturer. Different manufacturers will have different standards that they design their equipment to. Just look at how some manufacturer's equipment stands up to abuse, but other manufacturer.s doesn't.
Abscraperguy
Senior Member
Can't find the quote option so I'll do it this way.
SPECIAL TOOL THE REASON I WANT TO KNOW IS: after spending years sitting on equipment and inventing faster and better equipment I'm getting into building and selling equipment in a small way. I draw everything up on paper and then run it thru my CAD program where i check for tolerances and fit and then as a final test do a computer generated stress analysis. :waving
RobVG
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That's very cool. Do you stress your models to the point of failure?
Edit: Or does it just show stresses and stress points?
Edit Edit: Maybe I should just ask "How the heck does that work?"
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Does your liability insurance require a PE ( Someone that has a Professional Engineer's cert ) to sign off on all designs? That would be the person who would figure the safety factor.
Speedpup
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I know tubular steel scaffolding is a 4:1 minimum safety factor. Six foot span with scaffold planks rated for 50 lb sf will take 200 lb. sf
I wonder on the boom of a telehandler before failure?
I wonder on the boom of a telehandler before failure?
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Abscraperguy
Senior Member
Ya'll see if I can get pics here shortly. I use the Alibre CAD program. It has a good stress analysis program but when I want a real good one done I bring my CAD file to my engineer buddy who has a huge expensive Solidworks program. I just tell him what the loads are and from which directions and it will spit out a color coded picture; red failure and green pass and every shade in between.
hvy 1ton
Senior Member
After some much needed sleep and some thought about my post, 4-1 saftey facor is proabably better for most things. I know i had a chart at one point that showed different saftey factors
dirt digger
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it really depends on the equipment as well...the more of a safety factor the more the machine will weigh and cost. Unfortunately now it is coming down to dollars and cents more then brute and brawn. Take a look for instance at an old 955 loader and compare it to a current day one
regardless your not really going to need a FS of 4 for a skid loader or a "disposable" machine but something more expensive and expected to live longer will be engineered to a higher F.S...also the type of work it will be doing comes into play as well...for instance cranes and machines that can be used as cranes.
bridges and buildings for instance are designed with a typical F.S. of 1.5 where as air planes are designed with a VERY minimal F.S (weight issues)
what types of machines are you drawing up?
regardless your not really going to need a FS of 4 for a skid loader or a "disposable" machine but something more expensive and expected to live longer will be engineered to a higher F.S...also the type of work it will be doing comes into play as well...for instance cranes and machines that can be used as cranes.
bridges and buildings for instance are designed with a typical F.S. of 1.5 where as air planes are designed with a VERY minimal F.S (weight issues)
what types of machines are you drawing up?
Abscraperguy
Senior Member
Mostly compaction equipment. I'm trying to get some pics rounded up to post. Should be shortly.
hvy 1ton
Senior Member
Some how i managed to post this unfinished, oh well. Any way what i was trying to say was i had a chart somewhere that showed safety factors for different compoent types and service types. On a related note, when i used to do FIRST robots, we had some planetary boxes that where built with a safety factor of 2.5, me and about every other team driver in country shattered the sun gear on the second stage. They sent out replacements with gears made out of better steel. Upped the FS to 4 to match the old style gear boxes some still broke those boxes. Competition driving with component life being the last thing on your mind, since it becomes useless in about 2 months. Not so much with most heavy equipment, since you talking compaction equipment, might as well make it 5 or 6, more weight the better right?