Gross Axle Weight Rating (GAWR)

[Denny_A]

The following excerpt is from a post I authored in "Maintenance Discussion / Wheel Wells and Tire Failures"; Reply #21, in regard to a GAWR of 3500 lbs for  series 26, 27, and 30 TMs:
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"According to Mike Hulsey, the axle is rated for 3500 lbs. Howsomever - the wheel weight and axle weight are not counted in the total. Standard practise? Sprung vs. unsprung weight, and Mfr has already accounted for it's own axle. Axle plus wheels is more than 150 lbs. I will assume 170 lbs, for a reason which will be obvious."  
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After off-n-on inquiry with TM and Dexter Axle, I am suggesting a fairly simple rule of thumb for keeping your 26, 27 and 30 series trailers within the approved weight limit. This is the only rule needed. There is an alternate rule offered at the end of this post, just in case!

Rule of Thumb:  1) Support the trailer's tongue off-scale.
                         2) Determine the "axle load" (scale reading) on-scale.
                         3) Ensure the recorded load is less than, or equal to 3500 lbs.

Explanation:  

The axle is the weight limiting factor. The tires will carry 3740 lbs and the wheel assemblies even more. As explained in the quoted post, TM "do not count" the weight of the axle (100 lbs) or the weight of the wheel assembly (around 100 lbs) as weight actually *supported* by the axle.

When employing the "Rule", the trailer + axle + wheel assemblies are weighed by the scale. Therefore a weight of 3500 lbs *at the tires* is only 3300 lbs *on the axle*. When the weight distribution hitch (WDH) is connected, as much as 200 lbs of down force is transferred to the axle of the trailer. If, in fact, 200 lbs were so transferred, the scale would then display 3700 lbs, yet the axle would only be supporting 3500 lbs. I.e., still WITHIN LIMIT! The tire limit of 3740 lbs is also not exceeded.

Alternate Rule of Thumb:

     1) Connect the trailer to the tow vehicle and rig WDH for travel.
     2) With tow vehicle off-scale, trailer axle on-scale, weigh trailer.
     3) Ensure recorded weight is less than or equal to 3700 lbs.

NOTE:Ignoring the example below won't invalidate the "Rules" -  proceed at your own peril   .


Example:  3023TM loaded to max gross vehicle weight of 4092 lbs, with a tongue weight of 600 lbs.

Say 400 lbs of the tongue wt is carried on the hitch, and 200 lbs on the trailer. Then axle load is:

       Axle Load = 4092 lbs - 400 lbs on hitch - 100 lbs axle wt. - 100 lbs wheel assy wt. = 3492 lbs [check].


Cheers, and safe trailering,


Denny_A

Thanks for the detailed discription of the various variables in determining proper loading.

I look forward to weighing my TM soon and then seeing what I find.

Hopefully I'll fit within your first example and won't have to worry about the details explained later in your post.