Calc Required Torque & RPM for Automotive App

[Rob]

Hello
I am working on vehicle, for which i need to calculate following things

1. Required torque (Nm) to move vehicle from stationary position?
2. RPM of the engine at the time of torque mentioned in point number 1?

Available Input:
1. Vechile Weight(kg) - 4300
2. Engine Displacement - 3455
3. Gross Vechile Weight(kg) - 12990
4. Tyre Raduis (m) - 0.464
5. Gear Ratio 1st - 7.600
6. Gear Ratio 2nd - 3.7
7. Final gear Ratio - 6.142
8. Engine Max. Te(Nm) - 315 @ 1625RPM
9. Engine Torque = 230 Nm @ 1000 rpm , 241 Nm @ 1200 rpm (Actual Measurement)

Thanks,

 

[billy_joule]

Copied from your the identical question in this thread https://www.physicsforums.com/threads/calculate-motor-torque-requide-to-drive-a-cart.772433/

Please don't double up posts, it makes the forum messy.

"241 Nm @ 1200 rpm"

That gives a power of under 30kW, a third of the power of my last motorbike. Good luck shifting a 12 tonne vehicle with that. It's possible but probably not wise.

As for your questions:

1. Depends on the friction of all moving parts.
2. Zero. If the vehicle is stationary, so is the motor (unless you use a clutch).

Thanks for help

We are using dry friction clutch
Vehicle stationary and engine is idling, but when i put vehicle on 1st gear at what point of Torque@RPM vehicle start moving?

When the torque applied by the motor is equal to the friction of all moving parts.
There's no easy way of calculating this. Easiest way is probably to pull the stationary vehicle with a spring scale - the reading when the truck begins to move can be used to calculate the torque at the wheels required to move. Of course that ignores all the torque losses between the motor and the wheels which could be around 30%, it'll depend on the efficiency and condition of your drive train, this article is a good intro to drivetrain losses:

http://www.modified.com/tech/modp-1005-drivetrain-power-loss/