Heavyweight New Build Advice

[Jordanmann]

I'm building a new version of the heavyweight robot Chimera and looking to power it with 2 x 800w scooter motors with a gearing system. The current version of Chimera will still be in operation and running off 2 wheelchair motors but I want the new version to be better armoured and faster.

These 800w motors have an 11 toothed sprocket and I'm assuming a 2 stage reduction gearing system would be the best approach to get the required performance in a small body based on a ratio of 8:1, but is the best ratio and gearing solution?

Any advice would be gratefully received and if you have any other ideas on how I can do this please let me know. Also if you know the best place to buy sprockets and chains would be great.

Thank you.

Jordan.

[leorcc]

How big are the wheels? Is there a rpm number given on these motors, and on how many Volts?

[Jordanmann]

Hi Leo,
The motors we are looking at are these ones on ebay: http://www.ebay.co.uk/itm/like/800W-Electric-Motor-36v-6mm-Sprocket-Bike-Scooter-2800RMP-28-5A-36-Volt-MY1020/172051000823? hlpht=true&ops=true&viphx=1&_trksid=p5197.c100068. m2280&_trkparms=ao%3D1%26asc%3D20140211130857%26me id%3D02c23abd604349e58dc298e8e0177956%26pid%3D1000 68%26clkid%3D3846418150432835950&_qi=RTM2063723

We are currently using old Ford Fiesta wheels, with a rim size of 13 if that helps with the wheel size.

Thanks.

[typhoon_driver]

You'll need some heavy gearing on such large wheels. This will be why the older version got away with wheelchair motors. What's the outer diameter of the tyres?

[leorcc]

With a 8:1 gear ratio that would give you 23km/h (14 mph) top speed on 36V.

[leorcc]

You'll need some heavy gearing on such large wheels. This will be why the older version got away with wheelchair motors. What's the outer diameter of the tyres?

35.6 cm according to Google.

I tend to agree with Gary on this though, such large wheels you need some bigger gearing than that I think.

[team death]

I used a ratio of 8 to 1 and would double that to 16 to 1 -take off speed is more important than max speed I found,the arena is relatively small so don't go for a big top speed-for sprockets and matching chains I use Calda morley at wakefield

[timelord2003]

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