split axle flatbed

Well they are actually for a smoother ride. Back before air suspension there were a very few spread axle trailers but they had an equalizer beam between the front and rear axle to balance (equalize) the load between the axles. Rode a little better than a closed tandem but with the proliferation of air ride suspension the ride was significantly better on a closed tandem air ride than a spread axle spring ride. The biggest reason for spreads nowadays is ease of loading/weight distribution.

I've done the aviation thing for over 25 years off and on. Back when I hauled my very first set of thrust reversers for Boeing they required air ride on the truck and trailer all to reduce road shock transmitting through the suspension to the load.

 

Yea and we got high dollar for air ride equipment then too.
Made it justify the costs verses spring ride..

 

Go through any backwoods single axle scale house and if they're busy they'll only stop to weigh your steer axle and front spread axle. Screw either of those up and you deserve to get pulled around back, but DOT knows if those two weights are reasonable all your axles should be fine.

 

Somewhat related question:

As a Canadian, I don't have any experience with splits (we have trailers that do it, but I've never used the split) but is there a difference in how the weight balances between a split (either 10' or 12') and a Canadian tri-axle?

And why does the US allow the split but not Canada if there is no difference?

 

The US allows 40k lbs (20 each axle) on a 10' split while Canada doesn't. I don't remember what it is but I think it's only like 12k lbs.

 

Good info and explanation guys. These are the threads I like to read.

 

I think it's 10k actually. I remember asking the question way back when I started. It makes a split useless in Canada (which is why you never see fixed splits up here).

But is there a fundamental difference between how a 10' split and a tri-axle with a 10' span balances the weight between the axles with the air suspension? Because we are allowed 50,600 (~17,000 per axle) on a tri up here and you guys get 20,000 per down there.

 

I have scales on my trailer which weigh the axles together. The scales T into the air line which gives a weight for both axles together which can have a max of 40,000# for both axles.
Rarely do the two axles carry the 40,000# max. If the combined weight was at 40,000# then there might be a need to weigh them separately. But the air bags do adjust to where the weight is close to the same.
Under a normal load there should be no need for concern.

 

Normal weight allowed on a tridem is 42,000 in most states. Some will give you 60k but the formulas are based on the bridge calculations. I don't know why Canada does not give you 20k per axle on spreads. Maybe it has something to do with tire scrubbing on corners where you don't seem to get as much on a tridem. Now you can permit 60k pretty easily on a tridem with non divisible loads.