Grit dog
Black Diamond, WA
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A cheap one won’t shear either. Maybe unless your trailer rear ended by a loaded semi truck while you simultaneously an actual brick wall in front of you.
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valhalla360
No paticular place.
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Grit dog wrote:^Nope, but those may be good numbers for aluminum or brass or something. Hence why there’s no such thing as an aluminum hitch pin. You could rip 15000lbs in half just puttin the wood to it pulling your camper out of the driveway. (Not literally but it likely would not make it to the first campground.)
Any good hitch pin and maybe even the cheap $3 ones is going to have a shear strength FAR greater. Take normal 36ksi yield mild steel (that’s tensile strength). Ultimate tensile is more like 50ksi. Round numbers and approx.
Hitch pins are or should be 50-60-80ksi steel and shear is about 80% of tensile.
The factor of safety is 5-10 or idk maybe more.
Now bending is a different story. And why those silly reducer inserts for the trucks with 2.5-3” hitches are a horrible solution to being cheap with your hitch stingers.
The insert creates a short bending moment in the hitch pin and can and will easily pretzel a hitch pin. (And Waller out the holes in your hitch receiver, generally prior to bending the pin.)
I’ve cut off numerous bent pins due to those stupid little accessories.
Show me a strain guage showing 15k lbs on a 10,000 lb bumper pull. A truck with 7000 on the rear axle and sticky tires with a 50% coefficient of friction with only be able to apply 3500lb of shear force to the pin. Lock up all 4 wheels on a 10,000 lb truck and you are around 5000lb applied to the pin. But in normal use even those numbers are unrealistically high.
Also, try reading....I specifically said iron not steel as a worst case scenario and that steel can easily double the strength.
This is a shear failure so work in shear strength not tensile strength.
If you start mismatching parts of course you can have problems.
The point is even with the worst case scenario the pin is still several times stronger than needed.
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Grit dog
Black Diamond, WA
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^Yup, you’re correct. Although also correct. I didn’t pickup on your reference to iron, as in cast iron, of which NO hitch pins are made of. And I understand this concept better than most.
Why would you even say that? Be like using a wooden dowel or titanium as odd ball “examples”.
Although the silly original question may have prompted your almost as silly comparison?
3 pages in, it’s a hitch pin, it’ll be fine. End of story. OP can now sleep well with visions of hitch pins NOT breaking dancing in his head!
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opnspaces
San Diego Ca
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Grit dog wrote:opnspaces wrote:If the pin is smooth and undamaged I would leave it alone. I would replace it if it's showing signs of damage like maybe the receiver tube gouging into the surface of the pin.
A few weeks ago I noticed that a replacement pin for a 2 inch receiver is a whole $3 on Amazon. At that price I ordered a few extras since I have multiple hitches at home. I also keep an extra in the center console of the Suburban as a just in case.
Amazon
$3 Scamazon hitch pins are maybe not the best purchase…I’ll leave it at that.
I stand by my first post. It's a Curt pin not a no name overseas knockoff. Here's another link to the Curtmfg.com website where the pin lists for $4.95 if it makes anybody feel better about purchasing.
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swimmer_spe
Sudbury, Ontario, Canada
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valhalla360 wrote:mosseater wrote:Any idea what the shear forces required to chop it in two? There are anomalies in this world but betting the farm very few ever are sheared. The receiver welds would probably fail before that pin would shear. I'd sooner keep the one I have road tested than risk a new one these days.
5/8inch pin has a cross sectional area of around 0.30in^2.
It will depend on the specific steel but say we made one of iron (not steel for a worst case scenario). Iron has a shear strength of around 26,000PSI.
So each end of the pin would have a strength of around 7,800 but since both ends would have to shear to get a failure, 15,600lb.
A descent quality steel (nothing exotic) can be twice that shear strength.
Keep in mind, when you tow, you aren't lifting the weight of the trailer. The force needed to pull the trailer is a small fraction of the trailer weight. Even in a panic stop, the trailer would push the truck into a skid long before the force reached the weight of the trailer.
So long as there is no sign of damage or deformation, it should be fine.
Thank you for the math.
Now, what about fatigue? If you bought it brand new and it is used regularly and is 10,20+ years old?
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SUMRX4
VA
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The pin really isn't holding any weight. I towed an 8,000Lb tractor on a flatbed trailer about 60 miles once and after the trip I realized I never put the pin into the hitch. Won't do that again but that taught me the pin isn't doing any work.
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JRscooby
Indepmo
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SUMRX4 wrote:The pin really isn't holding any weight. I towed an 8,000Lb tractor on a flatbed trailer about 60 miles once and after the trip I realized I never put the pin into the hitch. Won't do that again but that taught me the pin isn't doing any work.
Thank you.
I have had to cut pins to get them out when somebody did something silly like put cable in receiver, then pin thru eye, but then all the force is center of pin. But I have had to cut more of the locking pins, where snot gets in key-hole, key won't work
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Grit dog
Black Diamond, WA
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SUMRX4 wrote:The pin really isn't holding any weight. I towed an 8,000Lb tractor on a flatbed trailer about 60 miles once and after the trip I realized I never put the pin into the hitch. Won't do that again but that taught me the pin isn't doing any work.
Your confusing ignorance and luck with physics….
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JRscooby
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Grit dog wrote:SUMRX4 wrote:The pin really isn't holding any weight. I towed an 8,000Lb tractor on a flatbed trailer about 60 miles once and after the trip I realized I never put the pin into the hitch. Won't do that again but that taught me the pin isn't doing any work.
Your confusing ignorance and luck with physics….
There have been times when I have had to telescope dry tubes. The only way to do it with reasonable amount of force is make sure there is no side pressure. If you lift the ball mount too high it is harder to get it out. The same would apply with TW on the ball
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Grit dog
Black Diamond, WA
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swimmer_spe wrote:valhalla360 wrote:mosseater wrote:Any idea what the shear forces required to chop it in two? There are anomalies in this world but betting the farm very few ever are sheared. The receiver welds would probably fail before that pin would shear. I'd sooner keep the one I have road tested than risk a new one these days.
5/8inch pin has a cross sectional area of around 0.30in^2.
It will depend on the specific steel but say we made one of iron (not steel for a worst case scenario). Iron has a shear strength of around 26,000PSI.
So each end of the pin would have a strength of around 7,800 but since both ends would have to shear to get a failure, 15,600lb.
A descent quality steel (nothing exotic) can be twice that shear strength.
Keep in mind, when you tow, you aren't lifting the weight of the trailer. The force needed to pull the trailer is a small fraction of the trailer weight. Even in a panic stop, the trailer would push the truck into a skid long before the force reached the weight of the trailer.
So long as there is no sign of damage or deformation, it should be fine.
Thank you for the math.
Now, what about fatigue? If you bought it brand new and it is used regularly and is 10,20+ years old?
A. His “math” ain’t right for STEEL, which all hitch pins are made of. And a “decent quality” steel is far more than double the shear value of cast iron.
B. “Fatigue” isn’t a real world consideration unless you could somehow get enough stress into it to have repeated elastic deformation (you can’t and won’t) resulting in strain hardening which will eventually leading to cracking.
However plastic deformation would cause it to be rendered unsafe. Never gonna happen with a proper hitch setup but somewhat common when those silly hitch stinger reducers are used on larger receivers to fit smaller stingers.
Finally physical wear could cause it to have reduces strength. For steel rigging subject to cross sectional loss due to wear, the criteria is a reduction of 10% or more of the effective cross section.
At the end of the day, unless you bend a pin as I described above, there is a 99.9999% chance that pin will outlast you, and your kids too. Maybe grandkids as well.
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