Carryfast:
bobthedog:
I have never said anything derogatory about my truck. I think this is the best truck I have ever driven, in fact. My “guvnor” would not treat me with that much disrespect, anyway. If I said it, he would ask about my reasons.…
Just so you know, the 5 tonnes I have on board are double decked ATVs. They take the entire 53’ of trailer and are up to the roof. I will try to get pictures in the morning so you can actually get an idea.
If it’s the ‘best truck you’ve ever driven’ then what the zb are you complaining about when you say that a 4x2 unit would have made a better job of hauling a 5 tonne payload in those conditions
Because it would’ve got less wheel spin.
First, one gets wheel spin when engine output power at that moment is too much for tyres to transfer to the surface. You get this limit when you multiply friction coefficient between road surface and drive axle tyres with weight on said tyre. In conditions BTD described he seemed to be constantly near the edge of this limit on a solid surface and if I read it correctly a pretty gently push to the pedal did get his wheels spinning.
Amount of force he could transfer per tyre was Force = coefficient * weight. Amount of force is limited by a single tyre because when one tyre spins all the power from engine beguns to go to the surface via that tyre (one driven tyre, you know). I’m now making a numbers bit of a hat, but I’d think their magnitude is close enough to reality for this example hold true. So, lets say weight over his rear axle is 4 tonnes from bogie, 1.5 tonne from trailer and 2 tonne from the load, making total weigh 7,5 tonnes. When you divide this by four you get a weight on a single double tyre which would be around 1875 kg. For a 4x2 unit drive axle weight is something like 2 tonnes less, which makes weight on a double tyre be around 2,75 tonnes. With this knowledge, when friction coefficient stays the same (which it will), 4x2 unit can transfer something like (1 - 2750kg/1875kg) * 100% = 47% more force to the surface before wheel spin occurs. This is why BTD said 4x2 would’ve made better job hauling his load in those conditions.
6x2 unit with tag axle lifted would have around the same, or bit more weight on drive axle than 6x4 would have on it’s bogie (due to load transfer effect on lifting the tag) even though it weighs a bit less than 6x4 unit. This means 6x2 unit can transfer something like (1 - 3750kg/1875kg) * 100% = 100% more force to the surface than 6x4 unit before wheel spin occurs.
Engaging cross lock doesn’t give 6x4 an edge on this situation as it would got wheel spin on both axles and 4x2 could still transfer more force to the surface without wheel spin than the combined forward force coming from 6x4’s spinning tyres is.