Automotive Power train calculations question

AI Thread Summary
The discussion revolves around calculating powertrain metrics for a small race car utilizing a chain drive instead of a traditional crankshaft. Key points include the need to determine torque on the wheels and acceleration, with emphasis on understanding the relationships between sprockets, torque multiplication, and power output. Participants suggest using engine documentation to find peak torque and operational speeds, and they explain how gearbox and sprocket ratios affect the final torque at the axle. Calculating acceleration is noted as more complex due to the variability of engine torque at different speeds. Overall, the conversation highlights the importance of understanding mechanical ratios and their impact on vehicle performance.
wasfy8
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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
 
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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.
 
this is exactly what i mean
need to calculate the torque on the wheel and the acceleration of the car
 

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




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