trailer 101?

On Sat, 21 Oct 2006 22:50:47 -0500, Don Foreman


Indeed. I personally will NOT weld a chain on anything that takes a shock load. Ive seen too many of them fail. Oil field stuff. Failed at the link welded. Weldment was fine..rest of the loop was busted open, or busted in half.
Gunner
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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On Sun, 22 Oct 2006 05:09:31 GMT, with neither quill nor qualm, Gunner

Hey, aren't you the guy whose spare tire dewelded itself and then _passed_him_ on the freeway? <bseg>
[I should talk. I can't even figure out how to weld a piece of angle to my truck frame up behind the spring and next to the gas tank. I think next time (try #5, sigh) I'll take the dremel to the weldable area to make sure it's clean and bright. I finally tried tiggin' the bastid and even that didn't work for me. It's a hellish place to get to with the spring and truck bed in the way. I should have backed it in and done it at your place when I was there.] </hindsight>
- The only reason I would take up exercising is || http://diversify.com so that I could hear heavy breathing again. || Programmed Websites
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I don't think that you are supposed to weld anything to your truck frame...
i
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On Sun, 22 Oct 2006 06:40:56 -0700, Larry Jaques

Yep. And Im a hell of a lot better welder these days. While not cosmetic..<G>..that little episode caused me no end of personal embaressment and has challenged me to not only learn to weld better, but engineer better as well. I welded up a cart for a buddies Bridgeport the other day, out of 5" channel. He wanted to be able to move it around the shop at will. It, when there is a BP on it..is .625 off the floor. I gave it to him Wed..and he called me up Friday to compliment me on the welding. Seems the dumb bastard...sigh...couldnt find his slings...so used a couple motorcycle tie downs to lift the BP up and set it on the cart.
The straps busted 6" above the cart.
He said there are marks on the floor where the cart bowed and hit the floor...but nothing bent..is still square and all 4 wheels still touch equally. It bowed..then came back into square.
Fortunately..the tire (and mount)..cringe..came off out in the desert..and has likely become the happy home for a family of Bishops Chipmunks (just doing my part for nature of course..cringe..)

My shop is your shop.

Gunner
"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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On Sat, 21 Oct 2006 22:50:47 -0500, with neither quill nor qualm, Don

Right, but I didn't think they used hardened chain on trailers, Don. These spec at grade 30. http://www.ontheball.com/chains.htm Only the clevis slip hooks go to grades 43 and 70, f'rinstance.

Well, it's kinda -hard- to weld wire rope, innit? <g> I think I'd prefer a wire rope to chain, too: It's -= quieter =-.
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If you should mistakenly load it heavy in back it most likely will sway uncontrollably and possibly separate and/or put you in the ditch. Not a pretty thing to see on the highway.
Keep your speed slow enough to keep the rig stable and to stop in a reasonable distance. Watch it very carefully going down hills heavily loaded. Once it gets unstable things can deteriorate rapidly.
Don Young
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wrote:

Once it goes unstable you are purely SOL unless the trailer has brakes.
If you keep the hitch weight at 10 to 15% of trailer gross weight, you'll be fine. I've never gotten even close to trouble with the 5X9 my neighbor and I built that can easily handle a 3000 lb load. The tires limit it to 3000 lb safe load, more than ample for us.
I do know what trouble is like. Going down a long steep grade into either Birmingham or Montgomery AL, forget which, doin' about 80, the trailer started doin' the watusi. Oooooh shit! I was 16 or 17 at the time. I was far from being an experienced driver, but I'd learned some physics by then. Fortunately, the trailer had electric brakes that I could hit without hitting the tow vehicle brakes. I figured that tail drag might be a good thing about then so I stayed off the vehicle brakes but nudged the trailer brake lever that was mounted under the dashboard. I got 'er under control without needing a change of skivvies but not by much.
My Dad, who I'd thought was asleep at the time, opened one eye, said "nicely done, now slow down dammit" and appeared to resume his nap. He was a CPO in the SeaBees on Guam during WWII, didn't rattle real easy and took no shit at all from the likes of me. But he definitely cut me all the slack he thought I could handle and a bit more for growth. Gave me a .22 rifle (Mossberg bolt action clip fed) at age 12 that I was free and trusted to go plinking with any time I wanted on summer days, and I surely did. I still have that pretty good rifle.
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Don, do you know what may happen if the trailer IS attached with safety chains, but becomes unhitched. Have you seen that happen?
i who always uses safety chains
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I've seen the remains. When things are set up properly with chains that are long enough to allow sharp turns but short enough to keep the trailer under control AND the load is set with the usual 10% tongue weight, the trailer tongue just drops down and bangs around. Usually grinds some metal off the chains (requiring replacement), grinds metal off the coupler or the small foot just behind the coupler, and/or bangs the hitch into the bumper or rear gas tank. You hit a bump, the hitch comes off, you hear a LOT of noise from the rear, you see the dust and sparks in the mirror, you slow down quickly, assess the damage. Beats killing someone in the oncoming lane.
If things are NOT set up properly, things get nasty. If the chains are too long, the trailer tongue thrashes all over the place, may inflict serious damage to the tailgate/trunk. If the load is unbalanced, too much load in the rear, the tongue will rise up, tongue is guranteed to clobber the rear of the tow vehicle as well as a good chance of fishtailing from side to side. UGLY. Worst case is for the trailer to come unhooked and do a head on collision with the opposing lane. REALLY UGLY. I have a co worker who was killed a few years back, we had a camper trailer do in a family of 4 a few miles from me this summer. It does happen.
I have a specific caution for RCM types: A standard single axle trailer loaded with something heavy like 2000 pounds of sheetrock can tow quite nicely. Just load it with 10% of the weight on the tongue, low wind resistance, life is fine. Now load the same trailer with the same weight Bridgeport mill with it's high center of gravity. On level ground, you can load it with 10% on the tongue. When you go up a steep hill, the CG of the mill shifts back, all the weight comes off the tongue, you have no control. Plus if your trailer coupler is going to pick a time to let go, this is it. Wind resistance is just going to add to the effect.
No one else has mentioned it but remember your brakes. Most states don't require brakes on trailers under 3000 pounds (some states have lower limits). Put a 3000 pound trailer on the back of a 4000 pound tow vehicle and your stopping distance almost doubles. Hit the brakes and it feels like a giant hand is pushing you through the stop sign.
And one more: picture driving with your trailer at 60 mph on the freeway in a light drizzle. The guy in front of you hits the brakes, you hit the brakes and dive for the next lane. Your trailer will jack knife instantly. Slow down, be alert, keep plenty of distance from the guy in front.
Ignoramus22711 wrote:

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Thanks Roy. I have a 3,500 lbs boat on a trailer. So far we did not have accidents, but the old trailer rusted to the point of nearly falling apart. When I saw cracks in it, I was #%#%$ing shocked.
i

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All EXCELLENT advice!
Gunner

"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences." - Proverbs 22:3
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Probably the most important piece of information in the unfinished 'Designing Trailers' series is that all traliers become unstable at some speed. The plan is to design a trailer with a speed of unstability higher than it would be towed. There is no information as to how to calculate this or even what factors contribute to a trailer being unstable. Hints, but nothing specific.
So, when in doubt, slow down.
--
J Miller
"RoyJ" < snipped-for-privacy@microsoft.net> wrote in message
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On Sun, 22 Oct 2006 14:03:55 +0000 (UTC), Ignoramus22711

I have never had this happen. I'm careful about using good hitches, securing them closed with a padlock, and always using the right size ball.
Note that safety chains should be crossed. In MN it's state law. The point is moot if both chains are fixed to the same point on the tongue, as is the case on my (factory-made) boat trailer.
I also mouse the hooks on the chains. A piece of heavy rubber with two holes in it that are slightly smaller than the hook diameter provides a quick and convenient way to do that.
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I have not seen that happen. I personally feel that good chains will minimize damage and risk to life. I know people who disagree and pull large enclosed trailers weighing several tons with flimsy chains or no chains. Their theory is that in the event of it coming loose the trailer will somehow move away from the tow vehicle rather than cause it to go out of control. To me that is sorta like not using your seat belt so you will be ejected from the car in a wreck.
Don Young
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Thanks to both of you... I always use chains, though I have been skeptical of their usefulness... Most of my towing is about towing a heavy 21 foot 3,500 lbs boat.
i
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On Mon, 23 Oct 2006 03:52:35 +0000 (UTC), with neither quill nor
quoth:

Consider it an insurance policy. If the tongue comes off the ball, the chains keep if from digging in and catapulting into something. They give you a chance to stop the mass before it becomes a weapon (of mass destruction?) <groan> If it flips and goes over the divider, hitting 3 cars while 27 more run into them, you's in a heap o' trouble, boy.
Properly connected, the chains keep the tongue off the ground.
--
REMEMBER: First you pillage, then you burn.
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Grant Erwin wrote:

Owning about 5 right now, I'd have to say that trailers are pretty simple. The basic wiring diagram for lights is on the back of most lighting replacement parts that you buy at Wal-Mart. Bearing buddies are needed for boat trailers to keep the bearing cavity pressurized to exclude water intrusion, otherwise are not necessary on trailers that don't go into water. Jack up a side and give the wheel a spin, if it sounds smooth, it's probably OK. You may want to repack the wheel bearings since it's new to you, but I doubt if you ever will need to again. I've owned my 16 footer since '91 and have never repacked the bearings. Don't beat on the hitch mechanism with a hammer. Beyound that, there's not much except replacement of rotten wood (which never seems to be done the first time with treated lumber).
--
Gary Brady
Austin, TX
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Grant Erwin wrote: but I'd really like to know quite a bit more

I have never seen any book that covers the basics. And I am sure that I won't cover everything, but others can add the things I miss.
1. The tow vehicle must be heavier than the loaded trailer and have a hitch rated for the loaded trailer.
2. The tires must be rated for the load.
3. You must have trailer brakes above some loaded weight. Your trooper friend can let you know the law.
4. The center of gravity must be in front of the wheels. That is as others have said the tongue weight needs to be about 10% of the weight. But think of it as the center of gravity must be ahead of the drag.
5. The center of pressure must be behind the center of gravity. I have never seen this stated anywhere, but it is something I believe. If you have questions on this google on model rocket design. This is pretty much the same as 4. but saying that the center of gravity must be ahead of the aerodynamic drag. Again not to the extreme or cross winds will be a problem. My guess is the center of pressure ought to be over the wheels.
Dan
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On Sun, 22 Oct 2006 07:13:08 -0700, snipped-for-privacy@krl.org wrote:

Be sure to look at the springs. I had an axle come out from under an old boat trailer (with a heavy boat and motor) I had just bought in the dark. Spring broke coming around an intersection at about 5 MPH. I had just pulled it 50 miles at freeway speeds!
Since yours was in an accident, alignment might be in order. Alignment is simple. With the trailer on level pavement, measure from the center of the hitch to a point on the axle near the wheel, repeat for the other side. Measurements should be near identical. 1/8" out is OK. If there is a second axle, it should be parallel to the front axle. Align the front axle first.
Ron Thompson On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
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OK, 10% tongue weight seems to be the norm. How do you know when you are there, in the real world? Without unhooking the tongue and weighing it? Even then, you would need the weight of the loaded trailer to do the math. I always measure the distance form the tongue to the ground empty, then again when loaded. If the tongue goes down, I can assume there is weight on the tongue. But, I don't know exactly how much. How do you guys know when its right?
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