# Automotive Power train calculations question

1. Feb 12, 2012

### wasfy8

hi,
i have some problems in power train calculations for a small race car has a chain instead of crank shaft converting motion to the rear side, calculating torque on the axle and wheels, forces and the acceleration of the car.
So, can anyone help or mention a guide reference ???
thank you

2. Feb 12, 2012

### xxChrisxx

Can you post a specific question regarding your problem, or the things you are trying to work out?

It's difficult to determine exactly where you need help. From what I can gather, you know the engine outputs, but have a chain/sprocket driving a solid axle. Did you mean propshaft and differential rather than crankshaft?

So it sounds like a Kart, or a motorbike driven single seater or similar.

3. Feb 12, 2012

### wasfy8

this is exactly what i mean
need to calculate the torque on the wheel and the acceleration of the car

#### Attached Files:

• ###### sprocket-hub.jpg
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4. Feb 12, 2012

### xxChrisxx

Sprockets, pulleys and gears all work in the same way with regards to torque multiplication. The ratio between inputs and outputs determine the change in speed and torque.

You can calculate your acceleration from the power output, unless you are factoring in losses at each stage.

5. Feb 15, 2012

### aishu2015

Can anyone help me to calculate the power train calculations.....

http://www.emfocus.co.in/automotive-powertrain.html [Broken]

Last edited by a moderator: May 5, 2017
6. Feb 15, 2012

### The Chase

I think Chris has answered this for the most part. Remember torque is simply a force across a length, therefore if you have documentation and/or technical papers for the engine you should be able to find out the engines peak torque and at what operational speed it is made at. Assuming peak torque to be 50 N/m at 8000rpm for example, and gearbox reduction in a certain gear to be 5:1 then you know gearbox exit torque will be around 250 N/m (if you disregard frictional, heat and noise losses), say your sprokets give a further 2:1 reduction you can assume that you will produce roughly 500 N/m of torque at the rear axle. I have pulled these numbers out of the air but hopefully you get the picture. Calculating acceleration of the vehicle is a much harder task as the engines torque will vary dependent on the speed it is currently running at which will vary as you accelerate through the gears.