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I am working on building an autonomous snow thrower similar to the one in this video.

I tore an old RX73 tractor down to just the chassis, by removing the engine, transmission, mower deck, brakes ... basically everything. Here are pictures of the Top of Frame, and the Underside of Frame after I cleaned it a bit.

In terms of steering and control, differential drive robots are dead simple to control vs. ackerman steering (traditional car steering).

It's often preferred in robotics to use two motors, one connected to each back wheel, and use a free caster wheel in the front, or use a chain to connect each back wheel to the front wheel on its same side.

Another popular method is all-wheel drive by connecting a motor to each wheel but use the same DC output for the front and back motors on each side.

Seeing as I already just two 250W Motors, and chains, it seems like the easier option is to use a chain to connect the front and back wheels on each side, rather than buying more motors.

I am concerned however, with this design, that the chain in exposed to the ground seeing as the underside of the chassis is not enclosed.

I image this could potentially cause snow to build up somewhere in that mechanism. If you look at the video and how the chassis is connected to the thrower, there is a pair of linear actuators with arms, so I can also switch out the thrower for the mower deck and this robot to mow the lawn next summer. So I am concerned about dirt, mud and grass getting stuck as well.

My questions are:

Are my concerns valid, or just lack of experience? If valid whats a good way to prevent that from happening?

What would you change about the drive mechanism? An additional two motors is not out of the question, they're approx $40 each

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    $\begingroup$ Please paste the photos directly into your post. Some links go direct to photos which is not ideal, but the ones that want me to log in to Google Drive are a pain. What's the alternative if you don't use chains? Gearboxes? Because I find the motor isn't usually the problem. You can easily buy motors. It's the gearbox. Would running the chain past some brush bristles work? TBH, I'm wondering why dirt and mud and grass would get stuck in a snow thrower. Isn't everything frozen over? And isn't this being used on pavement? $\endgroup$
    – DKNguyen
    Jan 3 at 3:00
  • $\begingroup$ @DKNguyen Thanks for the feedback, I updated the links to the images. The dirt and grass are for when I use it in the summer time as a lawn mower. Never used a brushless bristle before, seems like an interesting idea. Even with a gearbox, I still to tie in the front wheel to the back (driven) wheel somewhow $\endgroup$ Jan 3 at 3:20
  • $\begingroup$ "brushless bristle" I mean run the chain past some stiff brushes. $\endgroup$
    – DKNguyen
    Jan 3 at 3:40
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    $\begingroup$ concerns of jamming and icing tend to valid in that you should look into them. You were considering it for a reason. You probably want all wheel drive due to terrain concerns. Chaining and even outright treads are not a bad way to achieve this. Usual solution is to put a guard to reject anything big enough to cause a problem, and spring-loaded tensioners with redundancy (more than one point of conveying force to the same wheel) to increase tolerances. $\endgroup$
    – Abel
    Jan 3 at 4:00
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    $\begingroup$ just general common sense observation - mud+grease+grass is okay, will just make a thick paste with heavy grease and will protect for a few years even if neglected. Ice+salt+sand will take its toll faster, end up stripping lubricant and ruining metal finish $\endgroup$
    – Pete W
    Jan 3 at 4:30

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Let's first think about the snow blower function.

Depending on where you live and if there is salt (may be by road cleaning trucks ) in the environment the exposed chains' grease will shave and collect and salty dust and particles from pavement and form a sticky paste, making it hard to keep them from rusting. The chains tend to throw this stuff to under carriage too and cause damage.

As for attaching a mower, again an exposed chain is bound to get jammed in small surface roots and old dead plant sticks.

you could pick heavy duty chains and deal with occasional cleaning and maintenance, but your idea of having a robot control means you don't want to constantly observe the machine.

So your idea of using separate motors for front wheels make more sense.

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  • $\begingroup$ Thanks @kamran. Seems an all-around consensus that AWD is the best bet. $\endgroup$ Jan 3 at 4:27

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