odd trailer design ?

[rb1957]

i noticed an odd looking trailer this morning ... with three light looking axles well to the back of the flat-bed, well behind the obvious CG, which would put a reasonable load on the hitch. something that should be avoided, no?

 

[SnTMan]

Maybe a "special"?

 

[KENAT]

Was it a low loader/heavy duty one? They often have another short 'trailer' immediately behind the tractor which the main trailer hitch goes onto.

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[ornerynorsk]

Very common on super singles nowadays, at least in the upper midwest.

 

[btrueblood]

I think RB might be talking about a trailer being towed behind a pickup, i.e. by a ball hitch. A semi trailer always puts a high load on the tractor wheels, so that the tractor gets traction.

RB, I've seen combination horse trailer and camp trailers in the configuration you saw. The human quarters are in the forward section of the trailer. Humans being generally lighter than horses, and not (supposed to be) occupying the quarters during travel, the balance point of the trailer is probably pretty far aft (depending on how many horses are in there).

 

[KENAT]

You may be onto something btrue, plenty of trailers with ATV parking in the rear like I see out my way use a similar configuration.

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[CorBlimeyLimey]

Depends what you consider "reasonable". Tongue weights of ~500lbs are quite common.

If the axles were excessively toward the rear, the trailer was probably custom built for hauling a particular offset CoG load. e.g. A large fork lift with extended tines, or even a stack of other multi-axle trailers.

 

[rb1957]

btrue has it ... it was a flat bed being towed behind a ute.

it was someting like >20' long. i noticed a king pin brace underneath (obviously). i thought it was normal practice to have the load over the axles.

 

[ivymike]

if memory serves, yaw stability of a trailer requires a certain amount of tongue load compared to the polar MOI of the load... it's been a long time, but it sounds like the sort of configuration you'd want for hauling distributed loads like pipe (higher MOI / mass).

 

[Ron]

rb1957...yes, the load should be centered over the axle(s) on light trailers, otherwise the hitch load is higher which makes braking and steering more difficult.

 

[btrueblood]

Rb - do you mean this trailer had a standard 5th wheel hitch, in addition to the ball hitch that was being used when you saw it? It's probably a 5th wheel trailer that had a ball hitch adapter added. This would allow an unloaded trailer to be moved by a lightweight vehicle (pickup or ute), i.e. taken to where the next haul job is, and be hitched to a tractor (or heavier-duty pickup) there.