Chris Stoffel wrote:
It would be nice if someone can show us how to work it out when the reduction of gears is considered. It will make this thread better and more complete.
Crawler ratio/ crawler multiplier / Max Torque at wheel /max Force (at speed)/Force per kg (GVM) / Force per kg (Tare)
Compliments of Apoc
Disclaimer: Uninformed, no research, just very strong opinions
you see what happens when I'm too busy to post for a while.
you guys all forget how things work.
Torque at engine is meaningless figure if you don't know the reduction ratio and tyre size, whereas power is constant in the system. (less friction losses)
What actually matters for any kind of performance is the force you can apply to the mass. this is a function of available force and available traction.
Power to weight is only a meaningful guideline if the gearing is suitable for the power and traction. Pointless having 1000kW at 40 000 rpm in a 1ton performance car if you have it geared to the speed of light in first....
Apocalypse wrote:
Torque at engine is meaningless figure if you don't know the reduction ratio and tyre size, whereas power is constant in the system. (less friction losses)
You mean like torque to 1000cc ratio?
Disclaimer: Uninformed, no research, just very strong opinions
Interesting topic. HUMMER H3 Adventure, 328Nm on 1:1 from the 3.7-litre I5. Say, 17% losses for altitude at Gauteng, for non-blown car, we sit with a lousy 272Nm of Torque at the flywheel.
Then it gets very interesting, transfer case ratio, 4.03:1, which will be the Torque Multiplying Factor of the TC. This gives us 1097Nm on the TC output shafts. if we just look at that, before the 4.56:1 Axle (Diff) Ratios, with my H3 at 2340kg, we are looking at ca. 468.9Nm/ton, with me inside.
@Sennin, any thoughts?
2007 HUMMER H3 Adventure, 3.7-litre, Inline 5-potter, 4.03:1 Transfer Case Ratio, 4.56:1 Diff Ratios
Yes that’s true with the Hummer. It has among the best transfer case reduction which is something that people tend to forget. I think the only thing that beats it is the Rubicon Wrangler.
Disclaimer: Uninformed, no research, just very strong opinions
The Transfer Case ratio of the HUMMER Adventure and the Rubicon are actually the same, at 4:1. What would be interesting to know are the axle ratios of the Rubi. Adventure, 4.56:1.
2007 HUMMER H3 Adventure, 3.7-litre, Inline 5-potter, 4.03:1 Transfer Case Ratio, 4.56:1 Diff Ratios
Power is power, torque is torque, and neither really matter in the 4x4 world because it's all about force on the wheel at a given speed.
Power is absolute - less the losses in reduction and drag of course. at any given shaft, power is the same in the system (less losses and drag)
Torque can be multiplied and rpm can be reduced - and often torque at low rpm on a given shaft with a low motor rpm can be better than a high revving motor being reduced to high torque and low rpm.
I think I wrote an entire missive on torque and power and force and gearing and rpm....
