# Automotive Application

1. Sep 24, 2014

### 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,

2. Sep 24, 2014

### 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.

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/