Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: ArcMan on September 30, 2008, 09:21:24 AM

Title: Knobby Tires
Post by: ArcMan on September 30, 2008, 09:21:24 AM

I started trial runs of my yard robot last weekend.  One of the problems I had was traction in the grass.  I'm using the 8" dia pneumatic wheels from Harbor Freight.  They're salmon-colored, non-marring, ribbed tread.  Heckofa deal at $4 ea, but not great in grass.  What I really need is 8" dia knobby pneumatic wheels.  HF only has the knobby wheels in 10" dia.

Anybody have a good source for these?  I specifically want 8" knobbies (the squarish blocked tread).  They grip grass very well.

Title: Re: Knobby Tires
Post by: Trumpkin on September 30, 2008, 11:49:25 AM

Traveling sprinklers have those kind of wheels. you can get them here http://lrnelsoncorp.stores.yahoo.net/77506.html not pneumatic though. I don't know if they are 8" either.

Title: Re: Knobby Tires
Post by: ahab on October 04, 2008, 09:59:50 AM

http://www.mcmaster.com/

Search for Pneumatic Wheels.

Title: Re: Knobby Tires
Post by: ArcMan on October 05, 2008, 08:52:42 PM

Yeah.  I forgot about McMaster-Carr.  I checked there.  Good selection, but not the one I want.  Too expensive anyway.

As it turns out, my 8" wheels are going to be too small to give the clearance I need.  I'm going to go with the Harbor Freight 10" wheels.

Title: Re: Knobby Tires
Post by: Admin on October 07, 2008, 07:15:39 AM

Just a thought . . . drill holes into the wheels and hammer in short nails . . . not only does it cut grass, but it also aerates the lawn! :P

Title: Re: Knobby Tires
Post by: sabireley on December 20, 2008, 11:05:17 PM

Hi Arcman,

What kind of motors are you using to turn those large wheels and how much does your robot weigh?  I am building an off road robot to drive in fields that have been bushhogged and are pretty rutted.  I am planning to use differential steering.  I have been looking at similar wheels in Northern Hydraulics.  They also have 8" and 12" in knobby wheels on plastic rims that look promising.

Thanks!

Steve

Title: Re: Knobby Tires
Post by: ArcMan on December 22, 2008, 03:08:25 PM

Thanks for the info.  I decided to go with 10" knobby tires.  I have clearance issues with 8" tires.
My robot is driven with 2 24VDC wheelchair motors (5.4 kg-m of torque each).  It comes in at about 130 lbs.

Title: Re: Knobby Tires
Post by: sabireley on December 22, 2008, 09:37:49 PM

Thanks for the info. I just checked Harbor Freight. 4.99 for a 10 wheel on a rim is a good deal, though they look heavy.  I need ground clearance, and rough terrain handling ability, but only need a robot platform of 24 x 15 to mount the payload. I will play with some different sizes and see how it goes.

What do you use your robot for and what issues did you have driiving it in the grass? How do you control it?

Thanks!

Title: Re: Knobby Tires
Post by: ArcMan on December 23, 2008, 04:47:30 PM

Quote from: sabireley on December 22, 2008, 09:37:49 PM

Thanks for the info. I just checked Harbor Freight. 4.99 for a 10 wheel on a rim is a good deal, though they look heavy.  I need ground clearance, and rough terrain handling ability, but only need a robot platform of 24 x 15 to mount the payload. I will play with some different sizes and see how it goes.

What do you use your robot for and what issues did you have driiving it in the grass? How do you control it?

Thanks!

So far my robot has hauled a barrel of leaves around the yard.  When my mower bag filled up with leaves, I "called" it over to pick them up.  It's an R/C controllled bot right now.
It currently has 8" wheels attached directly to the wheelchair motors' gearbox.  The gearbox would bottom out when driving in and out of mulch beds.  The 10" wheels should take care of that.
Other than that, it works great in the grass.

Title: Re: Knobby Tires
Post by: sabireley on December 25, 2008, 10:04:35 AM

I saw you video in the vid section. Very cool.  Thanks for the info.