landowner:
Juddian:
Excellent point well put.
Shows how out of touch I am with the newer vehicles in transport, also shows that tyre tech must have advanced as well because 90psi in the drive wheel tyres years ago was running soft risking heat build up and blow outs especially if carrying max weights.
Never any wheelspin even with 120psi those days but then I only had 300 odd horsepower and more driver feel for the road with the older vehicles.
Progress has brought it’s own problems it seems
An old now passed friend/relation and i had quite a few discussions about such matters as power etc, we came to the conclusion that with all the emission equipment and the generally smaller in swept volume modern engines (when compared to a 14 litre ■■■■■■■■ you now need something like 500hp to put the same amount of useable at a moment’s notice torque and be as driveable as a decent 300/320 would give you in the 80’s when we’d upped to 38t.
Also the drive axle is doing a hell of a lot more work now but with often less weight imposed on it with a modern 6 axle vehicle than a 4 axled artic of previous design would have to shift, even if the drive axles of both designs were grossing off at 10tons the 6 axle jobbie’s axle is having to drive anything up to 12 more tons from the same 4 tyres, plus as we know with steel sprung trailer axles of old where invariably the trailer sat higher at the front then in practice the 4th axle weight was often higher by quite a bit than axle 3 if you put them over an axle weigher, in effect putting more weight still onto the drive axle.
When 38tons came less percentage of GVW wopuld be imposed on the drive axle in theory but lots of existing trailers were converted simply by bunging another steel sprung axle in front of the two already fitted, few gave the slightest thought to weight distribution, one instance i can recall was a bulk tipper trailer had another axle slung underneath, after a few weeks i happened upon an axle weigher at a modern farm, shockingly the three trailer axles grossed out at 5t 7t and 12t respectively, that was sent for immediate resolve but shows how poor some conversions were at the time where no one doing the conversions had paid any attention to the weights attained after.
A lot of those trailers were designed and built when artics had fixed fifth wheels and were lower riding as a result, stick a slider on and the front of the trailer’s gone up another 3" exacerbating the problem.
I regularly use an axle weigher and note the weights carefully, invariably at 43 tons gross there’s only some 9.5 tons being imposed on the drive axle if someone else who may not pay much attention to such things has loaded the trailer, i try to get the drive axle up to 10 tons at least because the whole outfit is noticeably more stable on the road and even that 500/1000kg less can translate into wheelspin pulling away and on roundabouts where it wouldn’t be the case @ 10,200+.
Note how easy these new designs get stuck in the smallest of snowfalls, though there are advantages to full air suspensions in that there are several ways to impose much more weight onto the drive axle, up to around 15tons if you know how…not as you’d run like obviously that but to get up an incline instead of blocking the road up for hours, well it makes sense.
Going back to the days of 32 ton work, it always seemed to be 900 x 20s that blew out seldom would 1000 x 20’s blow on the same work or weights.
For those not familar with split rim sizes, a 10 x 22.5 was the equivalent of a 900, an 11 x 22.5 equivalent to 1000 x 20.
…but it would be interesting if one of our brain boxes here could do the calculation for us, ie what mileage covered difference is there due to the difference in full tread tyres compared with recuts then down to about 4mm and ready for replacement.
