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Posted by stryped on April 19, 2008, 4:01 pm
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Been researching trailers and found this:
http://www.allstatetrailers.com/images/products/specsheet/30sa.pdf
Looking at the 14 foot long one, does it seem like the axle is not
placed right. I have been reading about how the ideal axle is placed
in a 60/40 configuration. This seems to have the back axle too far
forward? I like the trailer though.
Also, how heavy does a single axle trailer need to be before you
should put brakes on it?
Thanks again!
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Posted by Don Foreman on April 19, 2008, 5:03 pm
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On Sat, 19 Apr 2008 13:01:29 -0700 (PDT), stryped
>Been researching trailers and found this:
>http://www.allstatetrailers.com/images/products/specsheet/30sa.pdf
>
>Looking at the 14 foot long one, does it seem like the axle is not
>placed right. I have been reading about how the ideal axle is placed
>in a 60/40 configuration. This seems to have the back axle too far
>forward? I like the trailer though.
Summing moments about the axle and assuming uniform load, tongue
weight is about 4.8% of load. That's a bit light, but workable.
10% to 15% is usually better. Just moving the load c.g. a bit
forward would increase tongue weight.
>
>Also, how heavy does a single axle trailer need to be before you
>should put brakes on it?
Depends on applicable state law. In MN it's 1500 lb. A load
approaching 1500 lb without brakes significantly increases the
stopping distance of a 1/2 ton pickup tow vehicle, and it could be
dicey to drive in mountainous terrain.
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Posted by stryped on April 19, 2008, 7:21 pm
Please log in for more thread options > On Sat, 19 Apr 2008 13:01:29 -0700 (PDT), stryped
>
> >Been researching trailers and found this:
> >http://www.allstatetrailers.com/images/products/specsheet/30sa.pdf
>
> >Looking at the 14 foot long one, does it seem like the axle is not
> >placed right. I have been reading about how the ideal axle is placed
> >in a 60/40 configuration. This seems to have the back axle too far
> >forward? I like the trailer though.
>
> Summing moments about the axle and assuming uniform load, =A0tongue
> weight is about 4.8% of load. =A0That's a bit light, but workable.
> 10% to 15% is usually =A0better. =A0 Just moving the load c.g. =A0a bit
> forward would increase tongue weight.
>
>
>
> >Also, how heavy does a single axle trailer need to be before you
> >should put brakes on it?
>
> Depends on applicable state law. =A0In MN it's 1500 lb. =A0A load
> approaching 1500 lb without brakes =A0significantly increases the
> stopping distance of a 1/2 ton pickup tow vehicle, =A0and it could =A0be
> dicey to drive in mountainous terrain. =A0
Can you have too much tongue weight?
Maybe move that axle back six inches would work?
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Posted by Mechanical Magic on April 19, 2008, 8:15 pm
Please log in for more thread options > Can you have too much tongue weight?
Assuming the hitch on the tow vehicle has the proper rating, high
tongue weight is good. Witness a big rig trailer, the wheels are at
the extreme rear, the fifth wheel hitch at the front.
> Maybe move that axle back six inches would work?
On the 14' trailer the ratios are ~46%-54% NOT including the tongue
weight. If you move the axle 6" the ratio is ~43%-57% assuming a
uniform load. In reality, it's the driver's job to position the load
properly. The trailer does not force you to load it correctly.
>When is it ok to use a straight tongue with side supports and when is it best
to use an A frame with A frame coupler?
An Engineer will look at the load on the tongue, if a single straight
bar will provide the needed strength, then that's it. Side supports
are needed some times, since the single bar is relatively weak in that
dimension, and can also fail by "falling over". Double bars in an "A"
configuration are stronger still. It all depends on the load.
>If it "really" works why is that compnany building trailers that dont comply
with the 60/40 concept?
It's your job to load a trailer correctly. Also, the distance from
the hitch to the axle determines several things.
A long distance will mean the trailer cannot make sharp turns, and
will "cut the corner". Long distance is MUCH easier to back, since it
is not very responsive. Long distance can mean more tongue weight, to
the point where light trucks are not able to carry a fully loaded
trailer.
OTOH, a short distance from axle to hitch can make tight corners, can
be nearly impossible to back up (try a double cab, long bed backing a
tent trailer).
The problem with an improperly loaded trailer is that it is unstable.
A tail heavy trailer will start to move sideways, then correct, then
correct, like a dog's tail. I watched a trailer on HWY 80 North of
Reno, tail heavy. He kept increasing the speed, until it went
unstable. The trailer was going side to side about 6', to the point
the load was shifting, and the trailer was on two wheels left, then
two wheels right. If the load hadn't dumped, it would have pulled the
tail of the truck off the hwy.
Travel trailer folks discuss this all the time, and know to hit the
trailer brakes, at any sign of wagging.
Dave
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Posted by Don Foreman on April 19, 2008, 11:52 pm
Please log in for more thread options On Sat, 19 Apr 2008 16:21:04 -0700 (PDT), stryped
>> On Sat, 19 Apr 2008 13:01:29 -0700 (PDT), stryped
>>
>> >Been researching trailers and found this:
>> >http://www.allstatetrailers.com/images/products/specsheet/30sa.pdf
>>
>> >Looking at the 14 foot long one, does it seem like the axle is not
>> >placed right. I have been reading about how the ideal axle is placed
>> >in a 60/40 configuration. This seems to have the back axle too far
>> >forward? I like the trailer though.
>>
>> Summing moments about the axle and assuming uniform load, tongue
>> weight is about 4.8% of load. That's a bit light, but workable.
>> 10% to 15% is usually better. Just moving the load c.g. a bit
>> forward would increase tongue weight.
>>
>>
>>
>> >Also, how heavy does a single axle trailer need to be before you
>> >should put brakes on it?
>>
>> Depends on applicable state law. In MN it's 1500 lb. A load
>> approaching 1500 lb without brakes significantly increases the
>> stopping distance of a 1/2 ton pickup tow vehicle, and it could be
>> dicey to drive in mountainous terrain.
>
>Can you have too much tongue weight?
>
>Maybe move that axle back six inches would work?
That would bring tongueweight up to about 9% of load -- not including
the weight of the tongue itself.
There are a number of variables, tongue weight is just an indicator.
Variables included load weight, load distribution, length of tongue,
distance from hitch ball to rear wheels, length of tow vehicle,
weight and suspension of tow vehicle, yada yada. T.W. of 10% to 15% of
load seems to nearly always work OK but it's just a rule of thumb.
How you load it is just as important as the axle location.
If the trailer starts feeling skittish under way with a given load,
slow down! Then stop soon to redistribute the load.
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>http://www.allstatetrailers.com/images/products/specsheet/30sa.pdf
>
>Looking at the 14 foot long one, does it seem like the axle is not
>placed right. I have been reading about how the ideal axle is placed
>in a 60/40 configuration. This seems to have the back axle too far
>forward? I like the trailer though.