# Step on design gearbox for speed reducer

## Main Question or Discussion Point

Anyone can guide me how to design gearbox on speed reducer?

If I using spur gear on my design which type of spur gear has better lifetime and lower cost?
1) Brass Spur Gears
2) Steel Spur Gears
3) Stainless Steel Spur Gears
4) Ground Spur Gears

If Steady-state input speed 1000 rpm and Steady-state output speed 180 rpm so
1000/180 = 50/9 by factor this ratio I get 2:1 and 25/9:1

For my N2/N1 is better use ratio 2:1 or 25/9:1 ?

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I'm afraid in it's current form there isn't really a question to answer properly. As the answer is 'it depends'.
You've also included three materials and one manufacturing method.

What's the loading, the duty cycle, the required durability? How many sets do you need? Are there any standard you have to design to?

I'm not quite sure what you've done with the second part of the question either, as you are either doing a two stage reduction, so you need both ratios. Or you aren't getting the ratio you require.

I'm afraid in it's current form there isn't really a question to answer properly. As the answer is 'it depends'.
You've also included three materials and one manufacturing method.

What's the loading, the duty cycle, the required durability? How many sets do you need? Are there any standard you have to design to?

I'm not quite sure what you've done with the second part of the question either, as you are either doing a two stage reduction, so you need both ratios. Or you aren't getting the ratio you require.
Sorry for my poor english,
https://www.physicsforums.com/attachment.php?attachmentid=51083&stc=1&d=1348285245 (https://www.physicsforums.com/attachment.php?attachmentid=51083&stc=1&d=1348285245)
The expected life of the unit is 5 years, which is based on 8 hours per day and 5 days a week. A maximum of 5% failures are allowed over the design life of the unit. Minimise on the overall package size.

I read through KHK 3011 catalog (http://www.khkgears.co.jp/en/catalogs/pdf/3011en.pdf) I found that there are many type of spur gear and module so I want to know which type of spur gear can fulfil the need of client and have smallest overall package size.

Then i try out 1st step which finding the gear size, in my case i using ratio 2:1 for my N2/N1 but some of my friend using 25/9:1 for N2/N1 so i confuse about which ratio I going to choose for my N2/N1 ratio?

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