The GMC CCKW

I was looking at the manual the other day and it list 5,000 lbs as the towing capacity of a CCKW. The M7 series trailers are about 5,100 lbs empty. I am wondering what the 5,000 relates to? Tongue weight?

I believe the 5000 lbs means the "towed load " which would include trailer and load in the trailer.
But I have to agree it does seem "low"
If that is the case there sure is a lot of photographic evidence of the CCKW being regularly "overloaded"

John

You are right there John on both counts. These old trucks were constantly overladed in load and trailered loads. They preformed way beyond the design capabilities and did it on a daily basis.

The Army figures the load capasity of a vehicle is what is the Max load it can handle /carry during rough cross country no roads driving without causing undue stress or breakage to the vehicle. So 2 1/2 tons is what a CCKW can handle while driving off road cross country. But driving on improved roads it can carry 10,000 Lbs or 5 tons. The same goes for trailers as if you have ever loaded a 3/4 ton trailer to the max the spring pac hardly sags under the load. And 2 1/2 tons on a CCKW flexes the springs alittle, but it can handle more.
This was explaned to me by my motor cheif along time ago when I was an engineer and I had my M35 series Dumptruck. And he referanced some TM but I cant remember what it was, too long ago.

The 2.5 tons cross country and 5 tons on paved roads I understand, but I don't think that explains the trailer situation, especially when it comes to the M7 at 5,100 lbs empty.

As an side note. The M1 Searchlight trailer has skidplates under the springs to prevent the spring U-bolts from striking the ground. The actual ground clearance from the skid plate (slightly wider then the spring) to the ground is only about 4".

All I know is it will tow alot more than it was rated for that's for sure

If you look on page 41 in this months Army Motors
You will see a D4 Cat dozer being unloaded from the bed of a CCKW tipper
I'm not sure what a D4 Cat weighs but it must be way.... more than 10,000 lbs


John