# Converting engine torque to applied linear force

Hello,

For a given vehicle, I want to use a given chart for engine torque vs. engine speed (or hp vs. engine speed) and convert it to an approximate 'applied linear force' on the car (assuming no wheel slippage). I need a very rough approximation, so I've averaged the engine torque and assumed it's nearly constant over all engine speeds at 200 N.m.

I don't know how to convert this to an applied linear force... I'm thinking 200 N.m at the engine -> conversion ratio for the gearbox -> conversion ratio for the drive shaft = X N.m at the wheels. Then I can use the wheel radius to convert to a linear force.

* Is what I'm doing making any sense? Can I approximate the linear force I need in another way that makes more sense? The assumption I need to make is the force provided by the engine through all vehicle speeds is the same.
* If I'm on the right track, how do I account for the different gears in the gearbox?
* Is the engine torque = sum of wheel torques? Make the assumption all wheels get equal power (awd 50/50 central split)

I'd appreciate any tips

-Preet

## Answers and Replies

rcgldr
Homework Helper
Assuming no losses:

Wheel torque = engine torque x overall gear ratio
Wheel rpm = engine rpm / overall gear ratio