Kingpin to rear axle

There is a small flatbed company near me that has some 48 ft spread axle trailers, the rear axle is up under the trailer (like a California spread on a 53 ft flat) I have always wondered why on a 48 ft trailer ? They run out west, maybe it was a California thing at one time

 

Because that extra 6,000 lbs gives me a lot of room to be legal on the other axles. I have not had to get an axle weight while pulling a spread axle. It has been loaded correctly, the gross is 80,000 or less, my axle weights will be fine.

 

We hauled a 48 foot Ravens covered wagon with a 10 foot spread axle. It allowed us to load something some what heavy on the trailer end up to 20K per axle back there if necessary for a total of 40K. But it does NOT allow you to load more than 80K gross. there were many times I would cross a scale and find that the spread axles provided me a defense against a fine being heavier than 34K back there because the loading physics and dimensions just wont allow you to put it on the deck to keep it under 34K back there.

48 footers would slide the tandems anywhere forward and back along the rail, I think it was 500 or 750 pounds a hole until you got the 34K or less on your trailer or drive tandems. 53 footers create a problem. In some states such as Vermont I think there was a town called Rutland that will pull you over the moment they see that large '53 on the forward part of your trailer. Ive gotten pulled over a time or two through there.

Other areas sliding the tandems too far back on the 53 simply creates a dangerous situation in certain scenarios making for far too wide a turning circle for the availible pavement.

You can do a 48 all day anywhere in the lower 48! But problems begin when you cannot bridge the 80 properly on the tandems. Either youre loaded nose too heavy or too tail heavy and have to pull the freight out and reload it properly.

There are as you know weight tables and certain advantages are found in equiptment with triple axles, spread axles, even B trains and so forth in certain areas. But not all over the USA.

If you really want to have fun, check out the road trains down under. Whatever you put onto your tractor will take about 10 seconds or more to travel the length of your train.