Tractor pulling sled

[f150dan]

I have been trying to come up with a few ways to build a pulling sled for my rock crawler and a few other trucks I've got. I was thinking about making a pulling coarse 30ft long to use it on. I think the sled should weigh 50-150lbs. (including the weight) so it would be compatible with just about any RC truck.

IMO the easiest way to do make the weight move to the front would be to have a small rope that would wrap around one or both of the drive axles of the sled. That is the least complicated way I can come up with, but once the weight got to the top of the sled the wheels would lock up and slide. And I was planning on trying to get the weight to be all the way up top by 3/4 length of the track. I'm not really sure how it works in 1:1 scale, but thats what I was thinking.

My next idea was to find a small chain and sprockets to move the weight, but I'm not sure where I can find chains and sprockets small enough. I also don't know how much resistance that would be for a RC car to move it.

So far, I'm thinking about making the main trailer frame out of 1/4 or 3/8 square steel tubing and then make the ramp and front sled out of aluminum I've got lying around. The trailer needs to be heavy enough to turn its tires and not slide them once the weight gets started moving up. I'm also planning on running 2 axles under it with 2.2 tires/wheels.

Is there anything I'm not thinking about or unforseen problems that I might run into. What do you guys think? Do you have any suggestions? If I get one built, would any of you guys wanna see how your rig stacks up pulling it?

I've been seeing a sled on ebay called "The Draggin Wagon" but its kindof a classic or collectors item and I'm wanting one to use. I've also found other sled kits on the internet, but they are usually more then $500 bucks and some of them just don't look right to me. I'll try to make a quick sketch to show you what I'm thinking about building.

 

[crawlerman]

I have a pulling sled, it has been proven many times and broken several TLT's (it holds enough weight for a rock crawler, lol)
I can get some pics, there should be some on here also. Technically you are supposed to use a chain drive to be regulation, but i used a pully and cable system to get my reduction.

 

[f150dan]

I'm not really worried about it being regulation or not. If I can make it meed the spec's then thats fine, but that's not my main concern. Its just something for me and my buddies to mess around with. See if you can find some pics of yours.

Here's a quick drawing I did in Paint just to let you know how I want mine to look.

 

[Cole82]

http://www.rccrawler.com/forum/showthread.php?t=30287&highlight=pulling

 

[f150dan]

The actual angle of the weight ramp might not be that steep once I get it build, but do you guys see anything wrong with that design?

 

[crawlerman]

http://www.rccrawler.com/forum/showthread.php?t=30287&highlight=pulling

The shape and demensions are the easy part, its the reduction to get your full pull at 30 feet that is crutial.;-)

 

[f150dan]

Yea I'm worried about that. Actually, I would like to get the weight all the way up at about 3/4 length of the 30ft track. But I don't know how to get the axles to freewheel once the weight can't move anymore. So I will probably just have to match the reduction to 30ft like you said. I'm sure it will take alot of trial and error.

 

['83 chevy]

why over design it i'd just let the drive wheels skid causing more drag which will make it harder to get a full pull

 

[f150dan]

Well, I'm gonna have to run pretty sticky tires so they will pull the weight up instead of sliding. So I would say once the tires lock up, that sled will be very hard to move.

 

[trickedoutTLT06]

dont make the tires lock up!, thats just not scale!!! lol...im not sure how, but that drawing looks good to me, but the ramp shouldnt be so steep:shock:

 

[cvecmaxx]

maby use some small lawnmower tires, or something simmilar because i dont think 2.2's are going to support 50-150 lbs without running on the rims.

 

[Micropuller]

We use a chain to move the weight. Just before the weightbox reaches the front of the sled it runs off the chain. That way the rear-wheels can still spin free.

Here's the gearbox in the sled:

And the sled (our old one):

Here's a better pic of the internals for the gearbox:

Hope this helps.

Cyril

 

[f150dan]

How much weight does it usually take to stop a 2.2 crawler, Maxx crawler, or nitro MT's. I was figuring under 100 lbs. but I just wanted the ability to go more if I ever build a purpose built pulling rig.


If the tires I choose won't hold the weight, then I will get those little hard plastic pushmower wheels or something similar. They should have no problem with it.

 

[tombstone]

micro puller i have been a big fan of yours waiting and waiting for updates to your awsome pulling vehicles,

now on to my question,

how much would it cost for you to build me a twin engined puller

 

[Micropuller]

@f1 50dan:
That's hard to say. It all depends on the puller's own weight, gearing, hitch-height, track conditions etc.
Just to give you an idea, we once had a pull at an event where there were also some rc monstertrucks. These were by no means standard (lots of aluminum, stronger motors, extra baterries, you get the picture) They tried to pull our sled with about 10Kg (22 lb) of weight in the box. One didn't pull further then about 25 ft. The other stripped it's gears at about 30 ft.

 

[tombstone]

i would figure that stripping gears would be a big factor wouldnt aluminum gears help to stop the stripping?

 

[crawlerman]

Yeah, if you want to break your crawler, hook it to a pulling sled! Crawlers seem like they should be able to pull alot, but in reality, they are very weak. A lathe motor is nowhere near what a puller needs. I wouldnt even hook my TLT up to it, pot metal gears and plastic driveshafts wont make the cut. A stock based clod with internal steel gears, hitch, and pullmaster motors on gear reductions are the minimum needed to pull any kind of serious weight, more than one time that is. I saw Cole's tlt with 5 lbs added weight on the front end pull 30 pounds and snap the driveshat and rear servo/link mount like they were toothpicks. A puller needs to be built a lot heavier and stronger than a crawler. So I wouldnt think you would need a sled that can handle any more than 75 lbs maxx. Some of the big ones are pulling 600+ lbs though. You could always build the biggest baddest regulation sled in case you get a real puller someday, thats what I would do.

 

[slobin3d]

what about running a threaded rod with the end ground down so that when the weight reaches the end it stops moving the weight while letting the rod still spin