Trailer Questions

That four wheel setup is a "full trailer", where the trailer wheels / axles support the entire weight of the trailer and the draw bar only has a pulling load.
The normal OTR rigs you see are as you note "semi trailers" where part of the trailer weight is supported by the tow vehicle. The converter dollies used for tandem setups convert a "semi" trailer to a "full" trailer.
Permanent full trailers are typically low speed setups seen in farming, mining and circus uses.
Pete C.
Reply to
Pete C.
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Yesterday, while in Cedar City, Utah, I saw a modern Basque shepherd
shelter. For those who don't know what that is, it is a trailer for staying
in the mountains and caring for sheep. They are about 16' long or so, boxy,
except for a half circle roof. Door always in the rear. Traditionally,
they are green. This one was modern, and clad with the aluminum sheeting
just like a modern travel trailer.
My questions come from the suspension. On every one of these, I have seen
four wheels, two on each axle. Just like a toy wagon, or an old west wagon.
The front wheels are attached to a tongue, and have a tie rod turning
system, or in the old ones, just a pivot point. I'm sure there's a simple
explanation for this choice of wheels.
I have also noticed that this is about the only rig I have seen set up this
way. All the over the road trailers, except semis have wheels in the
middle. It probably has a lot to do with tracking and stability. Probably
stability at highway speeds, too. I have seen the four wheel front yoke
setup on low speed farm haulers, too, particularly hay wagons.
Anyone care to enlighten me?
Steve
Reply to
SteveB
Thanks for that! I have often been curious where the term "semi" came from.
Shawn
Reply to
Shawn
Hi Steve
Are you are asking about trailer design because you are thinking about building a trailer with the axels separated by an appreciable percentage of their width? If so, research "ackerman". The front wheels of a two axel trailer need to *toe out* while turning to avoid scraping or scrubbing. That can get complicated and is a good reason to use only 1 axel on a trailer.
Jerry
Reply to
Jerry Martes
"Jerry Martes" wrote ...
But a 4 wheel trailer is stable when you disconnect it from the pulling vehicle.
Reply to
B Fuhrmann
"Jerry Martes" wrote
Nah. I've just seen a lot of these over the years, and figured they were the best way to go for that trailer. I would imagine this trailer would be slow speed tow, and wheels spread out so that it could be dropped off in a meadow with little leveling. I have seen the insides of the old ones, and they are about as spartan as you can get. Two bunks, a table, and a small stove. I want to see the insides of the new metal ones.
Steve
Reply to
SteveB
Only if the four wheels are located at or close to the four corners of the trailer. The typical semi trailer has four wheels (or sets since they are duals) as well, but it sure as hell isn't stable when disconnected from the truck and relies on the landing gear jacks for stability.
Reply to
Pete C.
No, he's referring to a "full trailer" with axles located front and rear and typically steerable, same geometry as a car, but without any drive source.
Reply to
Pete C.
That type of trailer will require just as much leveling as any other type, it all depends on the terrain you park it on. The main advantage of a full trailer are it's continuous stability (connected or unconnected assuming it has brakes), and the ability to two it with pretty much any power source ranging from a dozer to a bunch of people pulling on a rope.
Reply to
Pete C.
I forgot to add that this type of trailer has been used in this configuration for + or - 100 years now in the US. And I don't know how long it was used in the Pyrenees before that.
Steve
Reply to
SteveB
Yep. Last time I checked, horses didn't come with 5th wheel hitches so you couldn't really go with a semi-trailer setup :)
Reply to
Pete C.
Actually, I believe that the word, "trailer," refers to a unit with one axel or with several that are close enough together to act like one. When you have wheels at the corners, the front set of which steer, the rig is generally called a "wagon."
The word, "semi," is a contraction of semi-articulated. A fully articulated vehicle bends in the middle but steers at both ends (think some fire engines and large city busses...). A semi-articulated vehicle bends in the middle but only steers at one end.
But, such terminology is always a bit dicey, since local usage may vary...
Jerry
Reply to
Jerry Foster
Hi Pete
Judging by the responses, I suppose my "ackerman" comment isnt what people are interested in. BUT, cars do like to have their front wheels *toe out* while turning. The "toe out" makes the car easier to turn because the tires dont scrub while the front wheels are turned. I thought, maybe, the OP was considering building a trailer with two axels, front and back. That kind of trailer sure is easier to pull (or push) when the front wheels are *toed out*.
Jerry
Reply to
Jerry Martes
On Mon, 27 Aug 2007 01:42:05 GMT, with neither quill nor qualm, "Pete C." quickly quoth:
I see no reason why 4 horses couldn't be hitched up that way for a lighter-tongue-loaded 5th wheel. They hauled 300 lb men around on their backs and thousands of pounds of wagon loads. Where's your blacksmithing spirit, boy? ;)
------ We're born hungry, wet, 'n naked, and it gets worse from there.
Reply to
Larry Jaques
A quick search comes up with:
trailer ?noun
1. a large van or wagon drawn by an automobile, truck, or tractor, used esp. in hauling freight by road. Compare full trailer, semitrailer.
full trailer ?noun
a trailer supported entirely by its own wheels.
semi trailer ?noun
1. Also called semi. a detachable trailer for hauling freight, with wheels at the rear end, the forward end being supported by the rear of a truck tractor when attached. Compare full trailer.
Reply to
Pete C.
Where would you plug in the air brakes?
Reply to
Pete C.
On Mon, 27 Aug 2007 12:53:35 GMT, with neither quill nor qualm, "Pete C." quickly quoth:
In parallel with the methane dollectors, of course.
------ We're born hungry, wet, 'n naked, and it gets worse from there.
Reply to
Larry Jaques
That's what I was afraid of.
Reply to
Pete C.
Sounds British.
Reply to
clare at snyder.on.ca
Nah, Britts has "Articulated Lorreys", Americans have "Semis".
Reply to
Pete C.

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