Trailer coupler rating

[furnacebrook]

Hello, I have a 12' x 8' flat bed trailer with brakes that weighs 1200lbs. It has a 5000lbs rated coupler on it with a 2" ball. The trailer is rated at 7000lbs and I plan on carrying 4000lbs of stove pellets on it a few times a year. This puts it over the coupler rating as well as the reciever drop hitch I have on my truck by 200lbs. The trailer hitch I have on the truck is a class 4 so I'm OK there. The question I have is, why does a trailer manufacturer put lower rated couplers on their trailer when they are rated for much more or, is this Ok to use?

Thanks for any help, Scott

 

[MikeD74T]

I'm guessing that since you have a rolling load the pull on the hitch will not be 5000 lbs. Likewise since you have brakes the pushing load will not exceed 5000 lbs. Only if you suspend the truck or trailer from the hitch would you exceed the rating of the hitch & I suspect there's a built in safety factor before failure as well. MikeD74t

 

[chvet73]

I don't why they would put an under rated coupler on the trailer. But I do know I would not exceed the rating.

 

[wushaw]

My BigTex trailer is that way also, 7k trailer 5k coupler and I have a 6k ball. I have had atleast 5k on my trailer many times and it has a 5100lbs of carry capacity.

Trailer manufactures do it all the time...who knows really why.

 

[Skyco]

Why? Because they are cheap. I bought a 7000lb rated car trailer a few years back and discovered days later the coupler was a 5000 lb rated one. Called the manufacturer who said "Oh it will be fine don't worry" I asked them to put that in writing so if it ever broke and caused an injury or death I'd have proof they said that.
They declined but sent a guy to town who cut off all the couplers at the dealer and mine and welded 7000 lb rated couplers on

 

[wushaw]

I know I just put in a reply to this but I just remembered something.

I was at Southwestwheel a few months ago getting some trailer parts and they have couplers in big tubs so I pulled a 5k and a 7k Bulldog and layed them on the counter and asked whats the difference....and the only answer was on the 7k coupler there is a 1X2X5/16 or 3/8 flat that is welded at the smallest section of the V just behind the ball retainer.

The rest of the coupler was the same thickness in material so that little piece of flat adds 2k worth of rating????

 

[furnacebrook]

Thanks for all the input guys,sorry to take so long responding. MikeD74T, I had a feeling you had something with that point. It just did not seem like all these big trailer manufacturers would put these lower rated couplers on if they were going to come apart on the road and I have not heard of any either. So, I got in touch with an old professional welder friend of mine who has made trailers for a living in the past. I asked him the same question posted here. He said the reason is just what you thought. The coupler and the ball and hitch will not have that amount of weight due to the trailer taking most of it. He said just for example, a 7000lbs GVW fully loaded trailer at that same weight would only have about 2000lbs on the coupler and hitch. And its a rolling weight as you mentioned. You would have to suspend the whole tuck and trailer to get the full load to bare on the coupler and hitch. It did still bugged me some though. If I put on a 7000lbs coupler I would need to upgrade to a 2 5/16" ball and a forged drop hitch because mine is only rated for 5000lbs the reciever is rated for 10000lbs as I mentioned so that was Ok. It would cost quite alot more to get it to full rating. I guess I wounder if what Skyco said about them being too cheap to put on heaver rated parts has a factor in there somewhere ? I'm going to keep it the way it is though as I don't usually carry that much weight more than to or three times a year.
Thanks again for the input, Scott

 

[Reg]

Thanks for all the input guys,sorry to take so long responding. MikeD74T, I had a feeling you had something with that point. It just did not seem like all these big trailer manufacturers would put these lower rated couplers on if they were going to come apart on the road and I have not heard of any either. So, I got in touch with an old professional welder friend of mine who has made trailers for a living in the past. I asked him the same question posted here. He said the reason is just what you thought. The coupler and the ball and hitch will not have that amount of weight due to the trailer taking most of it. He said just for example, a 7000lbs GVW fully loaded trailer at that same weight would only have about 2000lbs on the coupler and hitch. And its a rolling weight as you mentioned. You would have to suspend the whole tuck and trailer to get the full load to bare on the coupler and hitch. It did still bugged me some though. If I put on a 7000lbs coupler I would need to upgrade to a 2 5/16" ball and a forged drop hitch because mine is only rated for 5000lbs the reciever is rated for 10000lbs as I mentioned so that was Ok. It would cost quite alot more to get it to full rating. I guess I wounder if what Skyco said about them being too cheap to put on heaver rated parts has a factor in there somewhere ? I'm going to keep it the way it is though as I don't usually carry that much weight more than to or three times a year.
Thanks again for the input, Scott

The coupler's rating is about the towed load - NOT as you seem to have concluded, about what it can take suspended from or loaded directly onto it.

If you go through the whole trailer you will find similar mismatches in other places, e.g. the tires COULD take more or less load than the axles, typically more. You are limited by the lowest rated component - in it's role, not a fantasy role of hanging the trailer from it.

 

[MikeD74T]

The coupler's rating is about the towed load - NOT as you seem to have concluded, about what it can take suspended from or loaded directly onto it.

If you go through the whole trailer you will find similar mismatches in other places, e.g. the tires COULD take more or less load than the axles, typically more. You are limited by the lowest rated component - in it's role, not a fantasy role of hanging the trailer from it.

Reg, Yes, that's what we said! BTW I've seen pictures of a tow vehicle hanging off a cliff whth the trailer supporting it, but again, that's not within the components' design criteria. And actually tires may not be rated for 100% of capacity as the hitch carries a significant portion of the load. Have fought with NH DOT, and won, on that one with a 20T trailer. MikeD74t

 

[skipmarcy]

I had a 2" Bulldog coupler rated for 10k and 2" ball & mount rated for 10k, you just have to look elsewhere than Walmart for them.

 

[furnacebrook]

The coupler's rating is about the towed load - NOT as you seem to have concluded, about what it can take suspended from or loaded directly onto it.

If you go through the whole trailer you will find similar mismatches in other places, e.g. the tires COULD take more or less load than the axles, typically more. You are limited by the lowest rated component - in it's role, not a fantasy role of hanging the trailer from it.

I believe what I am trying to find out is not a fantasy rating of the trailer components abilities under extreme instances but rather if the manufacturers are correct in putting lower rated components ( specifically the 5000lbs rated coupler) on a trailer rated for thousands of pounds more overall.
What would be the difference between the "towed load" and the "load directly placed onto the trailer"??
By your point of being limited to the lowest rated component ( which I happen to agree with) than it would be the wrong coupler for a 7000 GVW trailer? There seems to be a huge disparity in opinions here but I would rather err on the side of caution or am I reading your message wrong?
Thanks again for the input, Scott

 

[kenmac]

Not all . But, most places only sell 2" 5000# rated balls. I had to look around to find a ball rated for more than 5000#

 

[MikeD74T]

I believe what I am trying to find out is not a fantasy rating of the trailer components abilities under extreme instances but rather if the manufacturers are correct in putting lower rated components ( specifically the 5000lbs rated coupler) on a trailer rated for thousands of pounds more overall.
What would be the difference between the "towed load" and the "load directly placed onto the trailer"??
By your point of being limited to the lowest rated component ( which I happen to agree with) than it would be the wrong coupler for a 7000 GVW trailer? There seems to be a huge disparity in opinions here but I would rather err on the side of caution or am I reading your message wrong?
Thanks again for the input, Scott

As much as the litigious society we live in is touted on TBN do you think it's likely that ALL trailer manufacturers use the same components in their trailers, purposely overrate their capacity, and remain in business for decades?

If you've ever moved something like a boat on a trailer by hand you can visualize the difference between towed & actual load. If the boat weighed 1500 lbs you could neither lift it nor drag it directly across the ground. When on a trailer the leverage of the tongue length makes it possible to lift the front of the trailer, a portion of the boat's weight. The bearings & wheels carry most of the boats weight and overcome the friction of dragging the boat. The hitch sees the resultant weight, not the actual weight. Even in severe braking most of the boats weight is carried by the wheels. If you run into a wall the hitch will see the full weight of the boat plus the force generated by its velocity. Then the hitch will probably fail.

Over the road log trailers in NH can be registered for 50 ton. You won't find them fitted with tires rated for 12500 lbs because the tractor carries much of the load. I looked at a new 20T tagalong trailer last night. The load capacity of the tires is just under 16T. The designed rating is based on the assembly, not the weakest part. A failure of the weakest part usually comes from exceeding the design rating thru extraordinary circumstance, like hitting the wall. MikeD74T

 

[wushaw]

I had a 2" Bulldog coupler rated for 10k and 2" ball & mount rated for 10k, you just have to look elsewhere than Walmart for them.

I've seen 8k 2" ball, I have one but a 10k 2", I have not seen or heard of this animal.
Got a link of who has this?

 

[skipmarcy]

Sorry, I don't know where to get the 10k 2" ball online. I bought mine from a trailer supply outfit in Ft. Pierce, Fl., along with the 6" gusseted drop mount I used on my F250 to pull my tractor. The ball had the same diameter shank as my 2 5/16" ball, I think it was 1 1/4" shank. They both were stamped for 10k rating. My Hurst 20' equip. trailer had a cast Bulldog type coupler with 10k rating stamped into it, not sure if it was the Bulldog brand. I just sold my F250 and 2 heavy trailers about a month ago so I don't have them here anymore. That Hurst trailer was a 14k trailer by the way, with that 10k rated coupler. I wondered about it for awhile but in the 7 years I had it I'd hauled my tractors around thousands & thousands of miles on all kinds of roads and fields.

 

[wushaw]

Yea that 8k I have is also 1 1/4" shank.

Interesting on what makes one 8k and the other 10k with same shank size and that 10k probably had a tapered shank from the ball to the base also.

 

[amigauser]

Here is a 2 inch ball rated for up to 12,000. I am sure there are other sources online to.

Curt Hitchball with 2 inch Ball Diameter-Optional Shank Diameters - Hitch Balls at Trailer Hitches

 

[Kendrick]

there are 2 points to this. 1 is how the trailer is designed to distribute weight when properly loaded. the balancing act between weight down on the hitch vs the weight on the wheels.
2 is, what constitues resonable risk. how much must a trailer manufacturer overbuild a trailer to be reasonably safe from litigation when some one misuses a trailer and it fails. the trailers have to be built to handle some over exertions due to user error. ie 40/60 so that the toungue is lifting the tail of the truck due to load shift during use. handeling a left side heavy trailer because some one has 1 full tank and 1 empty tank on the trailer with 2000lbs of liquid in the tank. the users tendancy's to not follow the weight or load specifications are part of the "proper" build process for a good trailer or any tool for that matter.

users view of the product also falls in to play as well. some one mentioned the in writing issue and how the manufacturer just replaced all the fronts in town. it is easier for them to not have to answer those questions then to find out. it also is better to make a product the user doesnt question right off the bat.