Rotational torque

flattop1

Dawg 89
A gear ratio is a gear ratio true or false . Brings about much discussion.
Heres a link to some engineering stuff .
https://www.khanacademy.org/science/physics/torque-angular-momentum/torque-tutorial/a/torqueA small view in case your interested .
Screenshot_20191013-162641_Chrome.jpg
 

Lykkan

Member
Gear ratios can either favor torque by forfeiting potential horsepower, or favor horsepower by forfeiting more torque. Torque is a measurement of power, horsepower is a mathematical equation for work over time
 

95 shaw

Site Supporter
A gear ratio is a gear ratio when it comes to transferring rotational speed.
A gear ratio is not a gear ratio when it comes to transferring rotational torque.


The mesh point in a chain/ sprocket system is the pitch diameter of each sprocket.
The chain can be thought of as merely an idler gear which both driver and driven sprocket act on at the same diameter mesh point, keeping rotation in the same direction for both shafts.

http://taylormhc.com/wp-content/uploads/2016/11/Sprocket-Engineering-Data.pdf
Page 21 for 35 chain sprocket pitch diameters.

Just trying to get all the info in one location for ease of viewing.

It's not really rocket science.
 
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flattop1

Dawg 89
Your right its not rocket science .
I'm certain we all studied levers , mechanical advantage and more in school .
Some has been forgotten . Maybe some one learns something . I did .
I really don't know how much torque is exerted on the wrench only that the nut came loose .
 

Ted Hamilton

Helmet Painter / Racer
The differential usually comes about between ratios due to losses of friction (heat.) Numerically, a ratio is a ratio but real world, YMMV. Mass of chain, pitch radius, etc. all play a part. This is why HP should be increased until that loss is negligible instead of low hp momentum racing.... :)
 

flattop1

Dawg 89
Acronyms are so easily misunderstood . YMMV .
Add 10 Horse power and a tenth of an inch pitch diameter , won't affect the Load Moment ?
👍
 

sundog

Member
Everybody thinks of the weight to give you momentum but you can't spin that weight up to speed for free.
 
Higher ratios do multiply torque.
Higher ratios do decrease top speed.
It is a trade off.
top speed vs take off speed Find the balance.
 
flattop1 said:


Who knew catenary tension even existed in a chain drive system .


Now, that is absolutely above my pay grade.

LOL
in physics and geometry a Catenary is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends. In other words how much droop does it have, that is the cantenary curve. And how much pull does it exert on the ends that are supported.
Example hang a 20ft piece of chain between two post of a clothesline.
Then tie a piece of bailing wire and measure the difference between how much force is pulling on the post holding them compared to how much they drop of sag.
In other words IN THEORY the shorter the chain the less frictional forces are exerted on the sprocket teeth. But to really get technical, you have to take into consideration the top span of chain and the lower span of chain. The rear sprocket on top gains a little help. But the front gear loses the exact same amount, same with the bottom so all that is really changed is the amount of friction.
So if you have it perfect. You might gain 1 centimeter during the entire race.
1 centimeter = 0.3937007874 inch
OR
25/64 inch I would not put a lot of effort into it.

Now hopefully it is in your pay-grade. And I feel like added absolutely nothing to this conversation.
Now it is time to discuss the cosine of the chain at different tensions. Another factor in winning races. just like octane.
 

flattop1

Dawg 89
The last link presented as i understand it .
Shows a 15 ft lb torque engine having 2 inch gear as 7.5 at the tooth and a 1.5 inch gear as having 10 ft lbs at the tooth .
Higher / lower ratios thats a whole nother discussion as it seems to be a different definition too different pepole . As in 3-1 is higher then 7-1 . 7-1 being high torque , low speed .
 

95 shaw

Site Supporter
Now take that torque all the way to the axle of the driven sprocket.

Do it for a couple typically used combinations of 4 to 1 gearing.
Probably need to round at 4 or 5 decimal places.
Yes, the effect is small, but we are not talking about an earth shattering difference seen on the track.

Plot a curve for both sprockets sets starting below regular rpm drop to above max rpm using the torque curve of the engine.
 
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95 shaw

Site Supporter
The last link presented as i understand it .
Shows a 15 ft lb torque engine having 2 inch gear as 7.5 at the tooth and a 1.5 inch gear as having 10 ft lbs at the tooth .
Higher / lower ratios thats a whole nother discussion as it seems to be a different definition too different pepole . As in 3-1 is higher then 7-1 . 7-1 being high torque , low speed .
In gear sizes. make sure you are using gear radius, not gear diameter.
 
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