Aquabot Repair, Drive Belts Slipping, Won't Climb the Walls

by T.S.

Aquabot Parts drive gear and sideplate

Aquabot Parts drive gear and sideplate

This is a series of Emails about a broken robot and subsequent repair.

Thanks for your reply. Actually, the bot isn't moving. It is hard to describe in an email but here goes... :o)
On the one side of the bot (like this picture)

there is a gap between the pulley (58 as described here) and the plate (45). So the belt closest to the plate slides off the pulley and gets caught between the pulley and the plate. I don't know if I put something together wrong when I replaced the pulley about a year ago or if something is just not working correctly. Thanks to your directions I have replaced the belts, and repaired the power cable from the bot to the electrical box and feel pretty confident about working on it but as it is now it seems like I need an "expert" to see what the problem is.

Anyway, thanks for your reply. If you have any suggestions I would appreciate it.
Thanks again,

Hi, Several things to check. The drive gear on the motor shaft has a channel to retain the belt. check that the top of the belt is under the fat side of the step pulley , number 56 on your diagram, before entering the channel

The top side of BOTH belts should run under the fat part of their respective pulley. The fix could be as easy as flipping the step pulley. If you do not have a step pulley...its all one size, make sure the top of the belt runs under it before entering the channel on the drive gear.

Seems the routing of the belt or the step pulley may be the problem.
Refer to this diagram.

There is also a washer in the side plate that holds the end of the motor shaft. Is it there? they sometimes fall out when the machine is taken apart.

I think the fix is easy once the problem is identified.

One more thing. Is the motor working, turning the drive gear?

Hi Curt.
Yes, the drive motor is working as far as I can tell. While the bot is in the pool (under the water), I lifted it up enough so I can try to make the tracks run. One of them would run intermittently and then it would stop. The other wouldn't run at all which is probably related to the pulley belts.
Also, it appears that the "shaft" rod (where the drive pulley comes through the whole body of the bot) is somehow off kilter like it's worn or something. I don't know if that is due to the wear and tear or what. That is what concerns me most. Plus the open space between the pulley and the plate. I think my bot just needs a good look over.

Hi T.S.,
Sounds like the bushing in the side plate that supports the drive shaft. I
called it a washer in the last message, may be missing or broken. On some
robots it is identical to the bushing that holds the wheels in the side
plate. This bushing keeps the shaft centered and supports the tip. This
part, number 51, may fix the problem assuming the belts are routed properly
and the stepped pulleys (if your's are stepped, one side bigger than the
other) are in the correct way...belts ALWAYS contact the fat side.

Sounds like an easy fix.


Hi Curt,
Thanks for all your help. I was able to find a local guy who took my bot apart, and basically put new parts on it. He did a terrific job, only replaced the parts I needed, and only charged me for the parts (which were pretty much the price I pay on the internet). So, anyway, that worked out for me.
The problem was that plastic hub piece that surrounds the metal center of the pulley assembly was worn away. (The right side end in this picture) So only the metal piece was exposed. So without the plastic hub it just slopped about in the bushing.

I hope that makes sense but I'm sure you probably know what I'm talking about. Maybe you could mention on your site (or already have) that this plastic piece does erode and would cause slop in the bushing located on the plate. (Or maybe you told me this and I just didn't get it). Nonetheless, thank you very much for your help and really just your kindness to respond to my panicked messages.
It was very much appreciated.
Take care,

T.S., I believe I mentioned the bushing in the side plate If you will pardon the bragging.
I am very happy you got it fixed for a good price.
I will make a page this week and email you when its up.

Actually, it wasn't the sideplate bushing at all. The problem was with the plastic end piece on the driveshaft. The plastic broke off and the shaft no longer fit neatly into the sideplate.

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