# Gear Box design

I have school finish project.. a clyinder which has 20 ton weight and 2m diameter and i need to turn it at 36rpm
the gear box must connect directly to the clyinder from one end
what should i do first of all how can i calculate torque and which steps i need to follow

## Replies

• Differential
Welcome to the forum!
Yes, you need to calculate the torque required to turn the cylinder. Your gear-box must be able to provide this torque with certain factor of safety. Also you need to choose best possible type of gears (spur, helical, bevel,worm-worm wheel) The factors like a) motor-shaft and driven shaft positions, speed reduction ratio, efficiency,accuracy will play a role in deciding gear type. Also you may need to design shafts on which gears will be mounted.
• zobtirik
Gears type will be spur
but the point i cant find the torque
how can i calculate
• Differential
Torque - Wikipedia
• zobtirik
ok i found the torque
now i need to make other stuffs thank you for help
• patel kartik
hi.
i make a project on gear box desing in two wheeler.
what should be required to make a gear box, how to working, etc
so, you send me everything material.
thaks.
• Differential
Karthik,
We don't send you everything ! Its you who does it and we help you do it !
To start with, see existing gear boxes of 2 wheelers of different makes. Analyse them in all aspects ! Then come up with what all things(components like gears, shaft, lever, case) you need to design to prepare a gear box. Then come up with the parameters of these components that need to be designed. eg. for shaft: its length, diameter, material, support, bearing, lubrication system, etc.

Do study and come back with what you did and your questions.
• zobtirik
Hi all
Now i know the total power transmited by engine its 300kw and the last gear will have 36rpm and 2m diameter as i said before it ll be connect to 40ton now what are the factors that i need to choose material of gears (it ll be spur gear) i dont know factor of safety all i know is these informations ( gear type,transmited power,output rpm,output gear diameter,the total weight of the clynder 40ton,dia:2m and length 6m )
What i need to do what is the first step and follow
• zobtirik
The other problem is i cant deside how many gear i ll use and how can i arrange them
so i cant start to calculate
• Differential
Nice to see that you have taken efforts !
Select standard factor of safety and material for spur gear applications. Factor of safety would range from 1.5 to 3. You might want to refer B. U, Bhandari's "Machine Design" book. No of gears will depend upon your speed ratio, shaft positions, etc.
• zobtirik
So i need to know something becouse i couldnt decide
My project manager (my teacher) didnt give me the input rpm just the motor power
so i wonder do i need to know the motor rpm?
Because i checked some books and most of them start with motor rpm and output rpm and decide to the speed ratio.
• Differential
Output rpm is something we desire and we want !
Now it can be achived by combination of various factors which include motor rpm, size of gears, no of gears, etc. So its a combination ! Now as you say you are not provided with motor rpm, you may choose it !
• zobtirik
Ok thank you again ๐
i will go and ask to him
after that im here again for your help ๐
• zobtirik
Hi again i choose a motor
its rpm is 1400
So how many gears i have to use
output rpm is 36
what are the parameter that i have to check to select proper quantity of gears
• zobtirik
No response?
• Differential
Hey ! I was out for a weekend ! ๐
Anyway seems you did a good job ! Now no of gears will depend upon combination of following factors.
1) your speed ratio (1400/36) = 38.88 ~ 39
2) gear size available
3) distance between input shaft and output shaft

Now as you are given input and output speeds, I guss speed ratio is no longer a variable factor. Also speed ratio is considerably more. So I would suggest to achieve it in 2 to 3 steps. (ie. gear train of 3-4 gears). Also I would suggest to use gear types which are specially used for speed reduction. (worm and worm wheen would be best, worm at driving end and worm wheel at driven end). Also you need not achieve all speed reduction only at worm-worm wheel. A part of speed reduction can be achieved at next step also.

Considering all these factors choose a best combination !

Wishes !
• zobtirik
Hi again
in my project i just can use spure gears so how many steps and how must be the gear train i couldnt calculate it
• Differential
May I know the reason why you cannot use worm and worm-wheel. See, its the most suitable gear for speed reduction. If you are not using it simply because it may not be available, then its not what Projects are all about. You have worked great till here and for this small thing you should not lose. What if your external examiner asks why you didn't use worm gear ?
Talk to your teacher about where you can get desired worm-worm wheel gear.
Let me know what you think.
• zobtirik
Because he want me to use spur gear ๐
But i made a gear train and its ok now (he told me its ok )
I have 6 gears i need to calculate their size and transmitted power
But generaly project going well now
• manas0108
hi everybody.can any body tell me about how to design a gear box?? it would be very helpful if any body can explain with an example or a simulation. mond u its about the arrangement of transmission shafts,no.of gears,no of speeds etc.

thank u.
• raj87verma88
So you need a simulation
• Ashraf HZ
Which software can be used for those types of simulations?
• just2rock
whats happening CE'ian..๐
• ShrinkDWorld
• benhur83
you can decide how many stage using reduction rate.
1. <8
2.<45
3<200

and also you must calculate this rate for example
input w=1500rpm ;output w=15rpm
speed reduction ratio 1500/15=100 then you must design 3 stage gearbox

maybe you can select 5 reduction for first stage
then you need 100/5=20 reduction also need
for second stage 5 also selected
then 20/5=4 reduction rate for 3rd stage and also you must consider if speed decreases at the same time torque increasing POWER=angular velocity*Torgue so we have constant power electric motor so the torque is the biggest at last stage of gearbox .
then you must first calculate last stage for failure criteria AGMA
• benhur83
Worm gear manufacturing is difficult and cost is higger than the others also efficieny is lowest because of sliding motion cause friction loss. And other disadvantage is diamension is bigger than gear train.

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