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06-11-2010, 08:30 PM
| #1 |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
|  large scale RC's
i am tossing around the idea of building a large scale RC crawler. i am thinking it will be between 1/3 and 1/4 scale. at work i design and build small materials handling machines that run on 24V DC. i am thinking of using a lot of the components that we use on our machines such as the transaxles and the equivalent of a esc. this would essentially be a MOA project, with each transaxle putting out about 5 1/2 horsepower. i would start by using the 13" pneumatic tires we currently use and maybe increase the size later. the width of the transaxle and tires is around 25.5" and the wheel base would be about 40". this thing will probably weight about 100 lbs wet, maybe less if i use a lot of aluminum. the part i am stuck on is what to use for the steering servo? i probably want something that is capable of putting out 50+ lbs at the tire. has anyone made something similar? |
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06-11-2010, 08:43 PM
| #2 |
| Rock Crawler Join Date: Jul 2009 Location: boise
Posts: 587
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the new hitec servo puts out 600 ounces of torque, and you could use 2 or even 3 of them if you wanted  |
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06-11-2010, 09:02 PM
| #3 |
| Quarry Creeper Join Date: May 2008 Location: Hartsville, SC
Posts: 461
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When I think of something that big. The first thing that comes to mind is maybe some type of rack & pinion design. Maybe find some way of mounting a motor pinion to a really strong servo and building some type of rack for the pinion to ride on. That would at least maximize the torque a given servo would put out. You loose a little when its stuck out on a arm. Like I said it will take some designing and engineering to pan out though. Could be kick ass though.
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06-11-2010, 10:27 PM
| #4 | |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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06-11-2010, 10:36 PM
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| Rock Crawler  Join Date: Mar 2009 Location: West of Eugene, OR
Posts: 942
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06-11-2010, 10:43 PM
| #6 | |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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06-11-2010, 11:14 PM
| #7 | |
| R.I.P. Chip   Join Date: Jan 2004 Location: The Crawler State
Posts: 13,938
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http://www.servocity.com/html/heavy_...vo__115__.html | |
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06-12-2010, 02:08 AM
| #8 |
| Quarry Creeper Join Date: Aug 2009 Location: Heilbronn/Germany
Posts: 293
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How aout this ->  or using the Motor of an windshield wiper?! Last edited by annedecke; 06-12-2010 at 02:10 AM. |
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06-12-2010, 01:05 PM
| #9 | |
| Quarry Creeper Join Date: Jul 2007 Location: Fort Mill, SC
Posts: 349
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wow-- those are frekin' cool. these ServoCity monsters are a possibility too-- they are used on RC powerwheels -- over 4000 oz. in. possible. | |
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06-22-2010, 05:35 PM
| #10 | |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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06-22-2010, 06:09 PM
| #11 |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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i've done a lot of planning. i still need to work out how to fabricate the knuckles to make the transaxles turn, but that should not be too hard.    |
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06-23-2010, 12:06 PM
| #12 | |
| Quarry Creeper Join Date: Jul 2007 Location: Fort Mill, SC
Posts: 349
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Here's what I used one on-- some video there of it in action. | |
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06-23-2010, 08:44 PM
| #13 |
| Newbie Join Date: Jun 2010 Location: Peoria
Posts: 2
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When I built my Power wheels I used a relay controller from RobotMarketPlace.com. I used this to control a regular linear actuator. The only thing is it does not auto center like a regular servo.
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06-24-2010, 02:14 PM
| #14 |
| Quarry Creeper Join Date: Jul 2007 Location: Fort Mill, SC
Posts: 349
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Wow-- I just noticed the 32" wheelbase-- that is BIG! What are you going to use for tires? This is about the size of a Powerwheels. They are fun to drive.  |
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06-25-2010, 04:47 PM
| #15 | |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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the tires are 13x4 knobby tires we use on our machines at work. they are on a split rim and i should be able to make internal bead locks for them too. they accept a 19mm keyed shaft. they come from our transaxle manufacturer directly from china. the transaxles are 5hp each and have a load capacity of about 1300 lbs each. i dont know that the tires would hold this much weight, but the transaxle is very beefy. they use a 4.5" diameter motor. | |
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06-26-2010, 08:46 PM
| #16 | |
| Quarry Creeper Join Date: Jul 2007 Location: Fort Mill, SC
Posts: 349
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what are the axles originally intended for? Ideally something rated for that much weight will hold up well to the hits they are going to take. DO you have pics of these things? | |
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06-27-2010, 01:52 PM
| #17 |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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the transaxles generally come out of the scooter industry, but i think the ones we are using now are intended more for self propelled materials handling machines. think of small walk behind forklifts. this one in particular uses 19mm shafts which is just a few thousands under 3/4" as for pictures, i dont have any good ones yet. the rending is fairly accurate though, |
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06-28-2010, 05:37 PM
| #18 |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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this is probably the transaxle i would use. http://www.ruipuco.com/english/product11.asp?id=195\ does anyone know of a reciever that will bind to my dx6i and will run on 12 or 24v? |
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06-28-2010, 05:42 PM
| #19 |
| Pebble Pounder Join Date: Jun 2006 Location: Keizer, OR
Posts: 170
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i think this thing will work best with a droop or at least semi droop setup. i will likely run a gas damper for a shock, with a small spring on the rod. the problem is dampers typically only dampen one way, either extension or compression, but not both. i am thinking that i want it to dampen extension to minimize the unloading on climbs. any thoughts?
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06-29-2010, 10:10 AM
| #20 |
| Quarry Creeper Join Date: Jul 2007 Location: Fort Mill, SC
Posts: 349
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no thoughts on the dampening other than snow-plow shocks?  Those are sweet-- any chance they make them in steering-axle format, as well? I'm thinking of a set of axles for a 4x4 buggy for my kid. ` |
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