anyone here good with math?

i'm trying to figure out what gears would be needed to come up with a 11 to 1 gear reduction.the only gear that's a constant is 11 teeth as that's what's on the motor,and it doesn't come off.I'd like to keep the gears under 4" or so in diameter.If you can't help can you point me in the right direction to sites that can?

 

I'm good at math but you suck at telling us what we need to know in order to help.

 

you're going to want a 121 tooth gear if i understood your question. 11x11=121. what are you doing with these gears?

 

11:1 is a large reduction. What HP & RPM is the the motor. What is the full wheel (including tire) size. Usually, if yer doin what I think. A 20" wheel with 2-5hp only needs 3:1 - 5:1 reduction. To simplify your question just remember that for every 11 turns of your primary you want 1 turn of your final gear. If you want small chainrings a transfer case (engine mounted reduction case) or jackshaft is the way to go. If your drive gears (primary & final) are on the same side, just offset the chainrings next to each other with a jackshaft (two birds one stone).

What are you working on?

 

There are three (3) kinds of people in this world; those who are good with numbers, and those who are not

 

i know i suck at describibg things.Justin415 i want to use only a series of gears to get that ratio.I just want to mesh the right size/number of gears to meet my goal.I can't use any large gears as space is at a premium.Thanks for anyone that wants to help,and i've got wide shoulders if want to give me a hard time.Hell i'm married and used to it by now........

 

So you're setting up bicycle gearing are you?
Divide the big gear teeth by the small gear teeth.


Or is it a jackshaft deal?
Get the ratio from each gear combo and multiply.
A four to one and a three to one equals a twelve to one.

 

guess i left that part out i'm building a mini bike for my 4 year old son.I want a small contained gear drive system.I plan on using a starter motor for power.I want the 11:1 ratio as that's what the starter was made to run.Starter specs 10 hp,free speed 10,000 rpm (min)@ 10v,free current 45 amp max@10v,stall current 300 amp @4v,stall torque 3.2 ft. lbs@4.0v. That's all the technical info i can provide.I know i can make it work as it does with the 66 tooth gear i first used.I have a friend who had to starter motors on a go cart so i know it can work.Thanks to all

 

If only the 11tooth drive gear and one final gear: final gear is 121teeth (drive gear teeth X 11 = 11:1 reduction gear) If you want to make an 11:1 reduction between two specific gears you will need another 11tooth gear and another gear that is 1/11th of the number of your final gear.
example
11tooth drives 11tooth-that has a 9tooth gear on the same shaft. That 9tooth gear drives final 99tooth gear.

 

Hey, I have a 2hp briggs motor. I'm in Topeka Kansas. 25.00 buys it. It runs also! I pondered the idea of making my daughter a go cart with it.

 

thanks i understand what your saying but i need to end up with out any one gear being more then 40 teeth or so.I can't fit a single large gear on this project.

 

What is the smallest gear you have to work with?

 

yeah ,give us the amount of space you have to work with, i would just measure the 11 tooth gear diameter and get one with more teeth,but with the center hole the diameter of 11 tooth and slip it over and pin it in place, then you can use what ever gear ratio you wish by changing that gear that fits over the 11 tooth,thus giving you many options, any store like tractor supply or similar has gears in the tractor dept,done it many times , just figure out what ratio you need and get the gears

 

Am I way off?

11 to 31 with 11 on other side that 11 to 31 with 11 on other side that 11 to 31 with 11 on other side that 11 to 28 and that's it.

Comes pretty close to the 11:1 created by the 11 to 121 gear right?

 

what gear reduction would a transaxle from a riding lawn tractor result in?...... Just an abstract thought! that way[trike] it would not turn over as easy![in case YOU rode it]

 

Sounds like you got it right on the money.

If all your drive style gears on the inividual shafts are equal to the origional 11 tooth drive gear, just make sure the sum of your driven gears is 121.

<font color="orange"> YOU WIN THE BOOBIE PRIZE </font>

 

Kenny i think you might be on to something with my luck on two wheels ,Kilroy could i do the same without the extra 11 tooth gears if direction wasn't a problem?Would just reduce the amount of gears needed.I have some 48 tooth gears but don't look like they'd work.Thanks to all who replied.

 

At 10,000 RPM the 11 to 1 gear reduction slows the ouput cog down to 909 RPM. What is the diameter of your rear tire and what top speed are you looking for?

 

slow top speed,will play with tire size to get the speed slower or faster.

 

there's loads of cool little apps on this page, I think you'll need gearfind.zip
http://www.geocities.com/CapeCanaveral/Hall/4425/

 

This is a formula to help take some of the guesswork out of gearing.
RPM refers to transmission output RPM, not engine RPM.


RPM= Mph x gear ratio x 336 / tire diameter

These formulas are the same formula transposed to figure tire size, mph, or to figure what gear ratio you would need, but remember, RPM is trans output RPM:


Tire Diameter = mph x gear ratio x 336 / rpm


mph = rpm x tire diameter / gear ratio x 336


Gear Ratio = rpm x tire diameter / mph x 336

An example could include the following:

900 rpm x 20” tire / 10 mph x 336 = 5.35 ratio

The 11 to 1 ratio is irrelevant to your situation. It only helped determine the output shaft speed of your starter motor. This speed will of course drop as your battery looses voltage (quickly).

 

What about cones and a belt? Makes for a simple automatic system.

 

this is just an idea... I don't have a clue about the ratios, but what about using the planetary gear reduction off of a masonry drill? You can get them at harbor freight pretty cheap...