scamp safety chain safety

[WDavidG]

Expert advice for safely hooking up a trailer seems always to stress crossing the chains. On our 2014 scamp 13 the chains are fastened to the tongue with a single bolt so can't be crossed. I wonder how much of a safety issue, if any, this may be. I'm also a bit skeptical about terminating two chains with a single bolt, particularly since the load, if the chains are called upon to do their job, will create a sudden, perhaps extreme, bending force on the bolt.



I would like to think Scamp engineered this key safety element properly but it feels a little sketchy. Am I over thinking this or is it worth finding a welder to modify the chain attachment points?

[floyd]

They sell better chain sets with better connectors for under $15.
It is a simple matter to attach separate chains to the each side of the tongue frame if you are dissatisfied with the stock chains.
They are available for either single point attachment or double.
I too prefer separate attachment as shown below.
Notice I decided to bolt mine in place for easy replacement,even though I have a good MIG welder.



Remember that many trailers have a straight tongue on which the chain(s) attachment point(s) can't be more than a couple of inches apart to start with.

[Wayne Collins]

The best arrangement is two chains, each with its own bolt, mounted to the insides of the A-frame just behind the jack.
Drill the holes horizontally in the vertical center of the rectangular tubing.
Those anchor bolts should be equidistant behind the hitch ball as from the ball to the chain loops on your TV. Adjust the length of the chains to hang with a small amount of sag. with the chains crossed in the middle.
..Oh, and the bolts should be grade 8 for max strength. Use flat washers and self locking nuts.

[Byron Kinnaman]

Originally Posted by WDavidG

Expert advice for safely hooking up a trailer seems always to stress crossing the chains. On our 2014 scamp 13 the chains are fastened to the tongue with a single bolt so can't be crossed. I wonder how much of a safety issue, if any, this may be. I'm also a bit skeptical about terminating two chains with a single bolt, particularly since the load, if the chains are called upon to do their job, will create a sudden, perhaps extreme, bending force on the bolt.



I would like to think Scamp engineered this key safety element properly but it feels a little sketchy. Am I over thinking this or is it worth finding a welder to modify the chain attachment points?

You can still cross the chains, it may take a couple of crossings to provide the basket to catch the tongue. I've used mine for 13 years with a single attachment point and still able to make the crossed catch.

[Wayne Collins]

Originally Posted by Byron Kinnaman

You can still cross the chains, it may take a couple of crossings to provide the basket to catch the tongue. I've used mine for 13 years with a single attachment point and still able to make the crossed catch.

The chains are there only as a backup. As long as your hitch ball & socket are properly adjusted and locked down, it should never come apart.
I did experience the value of the chains - once - when I got in a hurry to hook up, and did not get the hitch all the way down on the ball. Lucked out though; it came apart going over a speed bump just as we were leaving the campground.

[WDavidG]

Interesting. What is the thinking about fore/aft placement? Floyd, it looks like your bolts are far enough forward that you can reach into the tubing end and place a nut so that the bolt is just through the coupler flange and one wall of the tubing. That seems a good mechanical fit. Wayne, as far back as you suggest fastening I assume it has to be a bolt through the tubing? Is that an issue compressing the tubing? Are there advantages to moving the chain attachment further back rather than close to the coupler?

[Wayne Collins]

Originally Posted by WDavidG

Interesting. What is the thinking about fore/aft placement? Floyd, it looks like your bolts are far enough forward that you can reach into the tubing end and place a nut so that the bolt is just through the coupler flange and one wall of the tubing. That seems a good mechanical fit. Wayne, as far back as you suggest fastening I assume it has to be a bolt through the tubing? Is that an issue compressing the tubing? Are there advantages to moving the chain attachment further back rather than close to the coupler?

Yes, it takes longer bolts to go through both walls of the tube. No need to tighten them so far as to squeeze the tubes. That is why you use stop nuts, or a jam nut.
As to placement, the bolts should be as far behind the hitch ball as the chain hook points on your TV are ahead of the ball.

[CarlD]

I agree with Wayne, grade 8 bolts, minimum 3/8 inch diameter and self locking nuts, commonly referred to as nylocks ( nylon lock nut).

This may help you find parts.


from the interweb


A nyloc nut, also referred to as a nylon-insert lock nut, polymer-insert lock nut, or elastic stop nut, is a kind of locknut with a nylon collar insert that resists turning.

[floyd]

Originally Posted by Wayne Collins

Yes, it takes longer bolts to go through both walls of the tube. No need to tighten them so far as to squeeze the tubes. That is why you use stop nuts, or a jam nut.
As to placement, the bolts should be as far behind the hitch ball as the chain hook points on your TV are ahead of the ball.

All good advice!

Although I preferred to place the bolt through the frame close to the box of the tube to provide better rigidity and allow the chain link to lay flat against the frame. I also went one up on the chain size just cause I liked them and they had safety closure clips.

[WDavidG]

Thanks all. This gives me some direction. I think I'll be modifying the scamp single point of attachment with two bolt connections following the specific advice from all of you. Your suggestions are consistent with my intuition and it's great to get some confirmation from smart experienced people that this is a prudent way to go. Your advice is appreciated
.

[Gompka]

I can say that the way scamp puts them, they still work just fine, it still creates a cradle when the chains cross to get to either side of the hitch. I'd rather not admit as to why I know they work ,but they do work.

[Thomas A Cronquist]

Originally Posted by WDavidG

Expert advice for safely hooking up a trailer seems always to stress crossing the chains. On our 2014 scamp 13 the chains are fastened to the tongue with a single bolt so can't be crossed. I wonder how much of a safety issue, if any, this may be. I'm also a bit skeptical about terminating two chains with a single bolt, particularly since the load, if the chains are called upon to do their job, will create a sudden, perhaps extreme, bending force on the bolt.



I would like to think Scamp engineered this key safety element properly but it feels a little sketchy. Am I over thinking this or is it worth finding a welder to modify the chain attachment points?

You must have 2 chains and crossing, it's the law. If the tongue comes off the hitch, it should drop down and be supported with e cross 2 chains.

[Wayne Collins]

In our tractor engineering dept. we once had a young engineer designing the fasteners for the sheet metal. He decided that 1/4 inch bolts would be enough to hold all the hoods and shields in place.
A senior engineer reviewed the prototype. He told the rookie to use 1/2 inch bolts. When asked why…. the elder engineer said, "Your calculations are right, the smaller bolts will do the job, but it doesn't look right.
So, Scamp's chains would probably do the job. BUT, they just don't look right being fastened with just one small bolt.

[WDavidG]

Originally Posted by Wayne Collins

In our tractor engineering dept. we once had a young engineer designing the fasteners for the sheet metal. He decided that 1/4 inch bolts would be enough to hold all the hoods and shields in place.
A senior engineer reviewed the prototype. He told the rookie to use 1/2 inch bolts. When asked why…. the elder engineer said, "Your calculations are right, the smaller bolts will do the job, but it doesn't look right.
So, Scamp's chains would probably do the job. BUT, they just don't look right being fastened with just one small bolt.

Thanks for this story Wayne. My old-fashioned engineering training leads to similar conclusion. Do the math, but don't ignore your instinct of what feels/looks right.

[floyd]

Originally Posted by Thomas A Cronquist

You must have 2 chains and crossing, it's the law. If the tongue comes off the hitch, it should drop down and be supported with e cross 2 chains.

Crossed chains is certainly NOT the law in Illinois.
Common sense though ( at least in this case) is not yet illegal.
Cross the chains where practical because it makes sense, not out of fear of punishment.

[Thomas A Cronquist]

Originally Posted by floyd

Crossed chains is certainly NOT the law in Illinois.
Common sense though ( at least in this case) is not yet illegal.
Cross the chains where practical because it makes sense, not out of fear of punishment.

Floyd, Thank you for the update on chains in IL. When I grew up in Chicago in the 1950- 1972, my Dad always taught me to use 2 chains, and when I started to drive and tow my boats, I always use chains. I thought is was the law, but I guess I’ll state legislators don’t really care about safety to their people or others. In Texas, chains are the law.

[floyd]

Originally Posted by Thomas A Cronquist

Floyd, Thank you for the update on chains in IL. When I grew up in Chicago in the 1950- 1972, my Dad always taught me to use 2 chains, and when I started to drive and tow my boats, I always use chains. I thought is was the law, but I guess I’ll state legislators don’t really care about safety to their people or others. In Texas, chains are the law.

Chains are the law in Illinois, its crossing them which is not required.


Still your guess is correct and always has been... Educate yourself, use common sense, and take responsibility.
Don't hold your breathe waiting for the state to care!

[ntsqd]

A note on thru-bolting through a thin-walled tube. It will crush the tube without a sleeve. If it doesn't happen on install because the installer was careful to not over-tighten the bolts then it will happen when those chains are suddenly loaded. Adding the sleeve is difficult, but it should be welded into place so as to distribute any load to both sides of the tube. That takes it out of the range of abilities for some people.
I drill a bolt clearance hole all of the way thru, then drill a sleeve clearance hole thru one wall only using the bolt clearance hole as the pilot hole. I cut the sleeve slightly longer than the tube's width so that it is slightly proud of the tube wall surface. Bolt it in place and then weld the sleeve to the one side only.


Or avoid all of this by making a bolting tab and have them welded to the tongue tubes. Make them such that the bolt hole for the chain is below the tube, and for sure make them so that the edges where the weld will be are NOT straight up and down the side of the tube. Simplest way to achieve this is to use a hole saw in the part of the tab in contact with the tube and make one big hole there. Weld only the inside edge of the hole and not the outside edges.



Use the biggest diameter bolt that will fit through the chain link. Grade 8 is good, F911 is a better bolt as they are both stronger and more ductile than a G8.

[RogerDat]

The bolt would have to pull out to fail I would think. Shear force on a bolt tightened on the chain won't get any leverage from or on the bolt. Also the crossed chains are not ridged so they will divert some force of trailer falling on them into front to back or side to side direction.


There may be a point to a single bolt. What happens if one chain fails and the other doesn't? Would that insure the trailer swings sideways? Would both chains letting go allow the tongue to drop and drag possibly stopping or flipping end over but staying in own lane?


Just speculation, I did have the original 77 scamp 1 7/8 hitch removed and replaced with a new 2 inch hitch, will have to look at the chain attachment to see if new one is one or two bolts.

[mizterwizard]

I suspect if the tongue of a trailer drops to the road surface it would have to find a pot hole or curb to have any chance of going end over end and even then it would more likely destroy the trailer frame rather than flip. I don't think even Top Gear in all their caravan bashing has been able to make one flip.

A second reason to cross the chains is to prevent binding on turns. If a chain goes straight forward and back it gets stretched on one turn and goes really slack on the opposite turn. This risks dragging it at times and snapping it at others. If you cross the chains and the cross is below the ball then the slack remains about the same all of the time. If the attachment points of the chains on the trailer and tow vehicle are equidistant from the ball then the amount of change in the slack in the chains on turns is minimized.

The bolt that secures a chain should be stronger than the chain so that the chain is the weak link (pun is coincidental).
It really doesn't matter what the diameter or grade of the attachment bolts are as long at the combination adds up to more strength than the chains.

One of the reasons to have two chains is redundancy. If there is a single failure point that can take out both chains then redundancy is lost. It doesn't matter that the single bolt holding the chains is stronger than the combined chains. If the bolt wears through, rusts out, comes unscrewed or any of a number of other things the whole system is compromised.

When bolting to thin material it is important to spread the forces far enough that the tongue doesn't tear out at the critical moment. I like the through bolt with a sleeve like ntsqd described. I would also include a pretty good sized thick washer on each side of the frame.

This is a safety thing and anytime safety enters the picture there are people who feel that all you can do is almost enough. There is no need to get carried away with this. You will never need it if you do a good job of hitching. Most of us make the mistake at least once of doing a poor job of hitching and then never again. For that one time though it is good to have the right setup. Just don't go overboard.

I have seen people use some pretty wimpy chain and bolts to meet the safety requirement. I guess if you don't care then it doesn't matter but it cost so little more to do it right that I just don't get it.