Society of Robots - Robot Forum
Mechanics and Construction => Mechanics and Construction => Topic started by: stopgo on January 25, 2008, 10:47:31 PM
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Does anyone know how I can gear two wheels together such that they both move when a single motor turns?
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uh yes...put the gear on the motor and the have one on the axle of the two wheels and put them at a perpendicular angle. and whola! you have a spinning wheel thing...next time google it or something.
~smash
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uh yes...put the gear on the motor and the have one on the axle of the two wheels and put them at a perpendicular angle. and whola! you have a spinning wheel thing...next time google it or something.
~smash
what he said. both wheels on a single axle and then turn the axle be it by gears or belt, etc.
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ya. but with belts they have to be tight. personally i think gears are a lot easier to use ;D
~smash
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Hmm, sorry, I should have specified. I actually want to gear together one side, like this:
http://blog.everythingrobotics.com/wp-content/uploads/2006/01/Image009.jpg
so I don't want to put the gears on a single axle. I guess I just need a line of gears with the motor shaft in the center and I need to figure out how to attach gears to the motor shaft and the shafts on which the two wheels are mounted.
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oh...that pic is very hard to make out whats happening...could you explain more plz.
~smash
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Actually, I just now see that those wheels look like they're on axles. That may not be way what I want. Specifically, I want to use differential drive, as outlined in Admin's tutorial, except I don't want to use casters for my front two wheels. I want to gear the right back wheel to the right front wheel, and the left back wheel to the left front wheel:
Left Back Wheel XXXXXX Motor Shaft XXXXXX Left Front Wheel
Left Motor
Right Motor
Right Back Wheel XXXXXX Motor Shaft XXXXXX Right Front Wheel
I'm new to mechanical engineering stuff, so this isn't trivial for me. My motor shafts have a keyshaft. I guess what I need is a gear with a notch sticking out in the center to lock onto the motor shaft, then have a set of gears on shafts to link up with the the right front wheel. Those gears won't have notches, and those shafts won't rotate - only the gears. That chain of gears will connect to a gear on the front wheel shaft - that shaft will be able to rotate. The gear on that rotatable shaft will also have a notch in it I guess. Likewise with the right back wheel. And a mirror image on the other side.
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4wd rc cars use a ribbed belt.
example-> http://www.redrc.net/wp-content/uploads/2007/09/wwspro4wd-1.jpg
you could take 2 of these gearboxes and make them run together. one front axle another rear.
http://www.pololu.com/products/tamiya/0114/
but you'll need to consider that 4 wheel diferential steering has ALOT more friction than 2wheel + caster
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Just a word of advice from past experience in making my own gear mechanisms. Unless you've got presice machinery, the right materials and good understanding of (shafts, ball bearings, gears, ex). I'd recommend using a system from a toy or something that you know already works right.
(my first gear system didn't go to well because all i had was hand drill with a few dull bits and a vise grip, long story short, some of the gears didn't make contract with each other as the motor ran :P)
bane.
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ya if i want those sorta things i just go buy one of those cars you pull back/ push and rip them apart.
~smash
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what cars? do you mean the ones that have springs in them?
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yes i think.
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ya if i want those sorta things i just go buy one of those cars you pull back/ push and rip them apart.
~smash
but where can you get one of those cars that are large enough for robotics projects?
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and with strong enough gears
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maybe we can reverse the shrink-o-ray. lol never mind, although there are tonnes of places to get gears i have heaps from meccanno sets ive collected over the years.
~smash
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this guy's (awesome) project might give some insight into one way to do it:
http://www.geology.smu.edu/~dpa-www/robo/jbot/jbot.html (http://www.geology.smu.edu/~dpa-www/robo/jbot/jbot.html)
for my own 4wd full suspension bot i just used 4 gear motors.
far simpler and less complicated machining.
KISS right?
dunk.
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beautiful design
this is going straight into my robotics notebook ( which you should all have)
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holy crap dunk. that link makes me want one too!
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Wow, thanks for all the feedback guys. Dunk, that link is really insightful -I think I'm going to take the timing belt approach. Now I need to study up on how all of this is going to affect my torque.
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i said the same exact thing dunk said
even did a picture :(
(http://i43.photobucket.com/albums/e398/RussianCommy/cool%20pics/1196991873429.jpg)
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ed, how come it seems like you have a pic for every situation???? ;D
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hehehe, sorry ed, you did recommend the same thing. for some reason the idea you mentioned only totally clicked when i was reading through the site dunk mentioned. i greatly appreciate your suggestions :)