Gears

I'm looking for gears that are the same as DB5 used. My robot is similar in design, I know there's gears in Technobots but I don't have a clue what to go for. The motor I'm using is Speed 900's.

Gears For what drive to wheels or weapon drive?

The wheels.

what gear ratio are you looking for?

If I knew that then I won't be asking.

So what exactly are you looking for? A gear ratio? What MOD of gears to go for? Your initial question is quite vague. It wouldn't be hard for someone to assume you already know what ratio you're using based on what little information you've provided.

If it's a ratio you want to know, work out what you want to aim for in terms of top speed of your robot, then use the statistics of your drive motors to work out how fast they'll be spinning at the voltage you intend on running them at. Apply a bit of basic mathematics to calculate how much of a ratio you'll need to drop the speed of the motor to a suitable speed at the wheel. Then decide on what number of teeth your gears will need and take it from there.

Go mod 1 gears and minimum ratio 6:1 ive ran 5:1 and its hard to control and not the best speed for a small arena id say 7:1 or 8:1 is a nice ratio to try. You could try a 1 stage but if your going 7 or 8:1 might want to do a simple 2 stage

8:1 2 stage sound good.

It really depends how big wheels you're planning on using. I've gone for single stage 4.5:1 reduction with 75mm wheels

8:1 would give you a nice mix of speed and power with 100mm wheels at 24v

I've got 4 100mm wheels and I'm running at 12v.

Ah I see, I'm planning to run on 13.2v Which is why I'm going for a lower ratio

12v id run 5:1 still fast and will have fair bit of push nice and controllable aswel as being single stage so easier and cheaper to make

Little bit of advice, don't be a snippy little so and so if I ask a simple question to get some background on an exceptionally general question. If you want help then a little manners goes a long way :angry: :angry: :angry: :angry:

Sorry I didn't mean to sound rude. But just to show you what my knowledge of gears is like. 8:1 may sound good to me but at the end it's just a number, I know what stage mean but that's it.

A speed 900 is rather powerfull. So module 1. (module=size of teeth)

The axle is 5mm, meaning Z12 (12 teeth) as a minimum.
Smaller as that and the inner diameter of the gear gets too small .
Formula for this. Module*Z-(2,5*module)= 1*12-(2.5*1)= 9.5mm

Mechanical guideline, single stage, max ratio 8 to 1. (wormgears are an exception)

Max size for the wheel-gear is 12*8= Z96. But that's a problem in itself.
Because a gear has an outer diameter module*z+(2*module).In this case 96+(2*1)=98mm.
The wheels can't have any wear and tear. Or you're driving on the gears.

Therefor, 12 to 90 is the practical maximum to be used. Means gearratio 7.5-1

Then the rest of the calculations.

RPM of a speed 900 @12V 6600 rpm 100mm wheels.

6600/7.5 * (diameter in meter*pi)*60/1000= 16.57 km/h theoretical.

for help figuring out ratios http://howto.killerhurtz.co.uk/calculator.htm