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hi all
for my crusher i now want to use 2x speed 900s, running on either a 25a abertooth or a scorpion xl/xxl-all running off 21v
however i would like to know a suitable gear ratio to use, in order to get good speed and high pushing power
any info/ help welcome
thanks alex
Depends on wheel size.
Let us take a 80mm Colson as the wheel.
@21V the Speed 900 runs 11550 rpm.
Aimed for speed is 20km/h
gives me a 9 or 10 to 1 gear ratio.
Youll end up with a 2 stage gearbox.
With a 8-1 gear ratio youll get about 24km/h
i was looking at using either 100mm wheels or 75mm ones
Simple calculation then.
1-10 ratio on a 100mm wheel gives 21 km/h
1-8 ratio on a 75 mm wheel gives 16 km/h
so i can use the 100mm wheels? matt said they would be to big
by the 1-10 ration i would need the gear on the motor shaft to have 10times less notches on correct?
such as 5 and 50?
thanks alex
Aboutish.
But I doubt you can find a 5 teeth gear to fit on a 6mm axle.
just go for the smallest T gear u can find and then the biggest size which is nearest the size off wheel if u want a 1 stage reduction
then guess the ratio and speed
is this the right sort of layout?
the page should work (i hope)
http://psychoflingteam.piczo.com/robotimprovements?preview=y&cr=5http://psychoflingteam.piczo.com/rob...preview=y&cr=5
also where do i buy the gears from?
thanks alex
Your Example is a single stage reduction, with 21V that will be really fast. We use a single stage with speed 900s, but on 12V and even then if we dont put our armour on it pulls a wheelie every time.
http://www.computerclub.nl/uploads/msrconcept.jpghttp://www.computerclub.nl/uploads/msrconcept.jpg
You can find gears in several locations, one of them is RS Components.
http://uk.rs-online.com/web/http://uk.rs-online.com/web/
We have driven the Hannibalitos with dual rate, so the voltage supplied to the motors was less than 6V, and still they are fast and fast accelerating.
I get my gears from technobots but if they dont have what i am after then HPC gears always does. Bit more pricey but the service is very good and you can get them to carry out various machining operations (at cost) on your gears.
ok so i just had the size of gears the wrong way around?
No i think it was right. Small gear on the motor, large gear on the wheel. it is a reduction, not an accelation you need.
hi leo could you reply to the email on my profile with your reply to my pm i sent to you?
thanks alex
just had a thought probably wont be suitable but, are there any tools which contain suitable gears which could be salvaged?
Alex, 100mm wheels will be WAY too fast for matts ratio. They are 5:1 and he just wanted the fastest he can get without burning the motors out and in a single stage.
The way you have drawn the gearbox will work, but with a 10:1 reduction on a single stage is quite alot and might not fit it in. I personally would build a 2 stage gearbox.
You havent stated what sort of speed you want so these ratios are just guesses. Do you want it really fast, real slow for easy control of in between?
Ploughbot is a fast featherweight with a theoretical speed of 9MPH, people say all these fancy speeds but they arent quite real.
Work out the sort of speed you want, it depends on the type of robot it is. I would Aim for the 8/10mph unless it needs to be really accurately driven.
Easy to work out the ratio you need.
Speed of motor divided by the ratio used. That gives RPM of the wheel, then work out the circumfrance of the wheel (diamtre x 3.124) that will give you the distance travelled in mm per rotation, turn that into metres.
Multiply that by the RPM at the wheel which will then give you metres per minute. Divide by 60 to get m/s. Then multiply that by 2.237 to get MPH.
Its worth making a note of that and tring to learn the rough workings out of ratios/velocities as it will help you alot.
hi grant
thanks for that, i will try it out to more i just used the technobots calcuator and did what you said start witht the mph (10) and found i would need 13.47:1?
alex
That sounds about right to me. I use 15:1 gearboxes on ploughbot to get 9mph and will soon be moving to around 16.5:1.
The higher the ratio the less your motor will have to work, so 13:1 sounds a good figure and shouldnt draw too much current. You will need a 2stage gearbox for that though. Not sure on the sort of money you have but I am making some more gearboxs for ploughbot, and a few other people will be using the same design so a few will be made if you were interested 16:1 ratio gearbox in a VERY lightweight package, but they will cost around the £250-£300 a pair mark.
you gettin ed to cnc them or makin em by hand grant?
Not sure yet - My gearboxes are different to eds so maybe by hand. Kenny might use some the same so he might cnc some.
Alex, sorry I completely miss understood your email, I thought you wanted to use two motors to drive the actual crucher mech. Please ignore what I said.
If anyone is interested, my gearboxes for Asgard are two stage astro driven like Grants coming in at about 800 grams including motor wheel, gears, bearings, shafts and casings. Cost, dont ask!
Alex, I already answered your pm with a pm last week or even the week before, did you not get it?
Anyway, Ill see if i can dig up my answer and send it again.
BonX uses 100mm wheels with a single stage 1:6.5 reduction on 24v.
13t on motor, 85t on wheel
plenty of power and speed, no melt-down of motor problems so far.
hi all thanks for th input
in an earlier post someone mentioned about cnc gear boxes could someone explain this too me please?
thanks alex
Made or manufactured via a CNC Machine.
http://en.wikipedia.org/wiki/CNChttp://en.wikipedia.org/wiki/CNC
(Message edited by woody on March 14, 2008)
what the gears are made by cnc machine?
No... The machining of all the bits and bobs including any mods to the bought in gears.
All CNCd rather than home built with a pillar drill and hammer.
(Message edited by woody on March 14, 2008)
Not that there is anything wrong with pillar drills and hammer built gearboxes.