Trucking in North America vs around the world

Is there a height problem if you go for 275/70 on the tag axle?
For safe winter driving tag axle truck is a must.

 

For real Scandinavian winter yes, for typical European 1cm of snow a bit of overkill to get tag axle

btw. newest Volvo has got modifed eco settings, driver can't change how eco the truck should behave, it's set to max eco all the time, drivers complain a little, not going to lie .. hopefully they will find a workaround for this.

Plus something is wrong with speed reading .. truck is set to 85, but it's actually driving 83-84. Daf style .. they will also take a look at this, I was the first to complain, but I'm not the only one with this issue.

 

depends how high you go with 5th wheel.

i think it is best case to chose scania for this calculation, their dimensions are very legal with standard 13.6m trailer, and i keep dimensions in head.

lets say that we need 1150mm 5th wheel, which is about standard for EU, although 1170-1180 is very common and way more usable (on 4x2).
to get 1150 on 315/70 we need special order of low 3mm L bracket (normal is 40mm) and 173mm sliding 5th wheel.

5th wheel would be 140mm behind driven axle, (1160mm from tag axle).
chassis height is about 975 unloaded.
when you lift tag axle, suspension height on rear goes up by 35mm, and truck with empty curtainsider trailer with raised tag and front trailer axle, you get 5th wheel height about 1185mm. it is still possible to get 2,7m internal height with 4.05m overall.

but we have a problem now
chassis height above 2nd axle is about 60mm more than on 1st, this means extra 26mm above 3rd axle over 2nd.

when you lift tag axle it goes up by 88mm and with 315/70 upper edge of tire is 115mm above frame.. if we look truck as straight line as semitrailer should be, we get gap between upper edge of semitrailer to neck of semitrailer of only 35mm.

if we remember that we have 1160mm distance from 5th wheel to tag axle, this means it can drive only on straight road.

if we put 315/60 on tag, we get extra 32mm (lets say twin are too heavy so we dont use 275/70), this could work OK, with good driver and front air suspension. however rear angle from trailer frame to truck frame is like 5,5 degrees (7 is minimum you can drive without issues), so driver will use front air suspension a lot.

if we use 315/60 on drive too and standard 40mm bracket, chassis is quite straight and will raise only about 10mm over 3rd axle, with raised tag we would get about 115mm between tire and trailer neck which is rather OK.
and 5th wheel is below 1190mm.

if you want care-free ride you need 203mm 5th wheel, so not possible to be legal anymore.

 

From another site…….

Outside Windhoek on my way to Walvisbay Namibia



can’t even imagine…….

 

US army puts their 170th BROSHUIS semi-trailer into use

 

That Oshkosh tractor pulling it is powered by a Caterpillar C18.

 

I wonder when US heavy haulers will start to understand the benefits of pendular axles?

 

They already do for some circumstances. Weight and deck height are problematic though.

 

Are the typical american trailer with jeep dolly etc lighter than a european trailer?
Deck height must be the same if you order a lowboy trailer.

 

Deck height can be as low as 18" or less for a cantilever trailer. With a beam trailer load height can be lowered even more. Additionally, placing those small tires under the deck cause problems with speed and heat.

The additional weight required for a tractor to have traction pulling a platform trailer must be added, which then kicks a lot of loads into super-load category and requires extensive and expensive route surveys, and can add weeks to the permitting process.

Finally, our bridge laws (not the bridge that one drives on, but the "bridge" length between axle groups) will prohibit such configurations, or at least require special permits that again add time and cost to a project.

Form follows function and laws - otherwise trucks would look identical around the world. It is not that we are so stupid and fail to recognize the benefit of configurations used elsewhere around the world. Our configurations vary a lot even between states and regions according state laws. There are quite a platform trailers used here, but they are used for very specific loads.