I had a little bit of time this evening to try the Mamba Max on 4S and a 775KV motor, and guess what ... no stalling. It got warm but never hot. The cheapest solution seems to be working. What I have working for me is gearing ... it is geared so low, I'm not that surprised that a Mamba Max can handle it, or I guess wouldn't be except for the fact that I had issues with the Mamba Monster.

I like the thought of mechanical brakes and if I had more ambition, might even do it, but I think this will work for my purposes. I'm never really that far away from the wagon when it's on the driveway, so in a worst case scenario can always run over and go stop it from rolling back down. The Revo is still I'm guessing 1/4 the weight of the wagon when loaded, maybe less, so when going forward, the Revo's brakes aren't going to stop it on a dime in any case, and as Dave points out, jackknifing can be an issue if you're too aggressive on the brakes. The key is to drive to the capabilities of the system: give lots of room for braking, and be ready to jump in if it looks like it's about to stall on a hill.

I will say, I am very impressed with the durability of the drivetrain on the Revo, especially given the locked diffs. Much more traction and I would be a little concerned about snapping parts in the drivetrain, so I'm not inclined to push its capabilities much more at this point.

Thank you everyone for your very insightful comments. A lot of good thoughts.

While I agree with you on this. Your trying to stop way more weight then a small brake disk is designed to. I'm not saying it needs to be a on off switch, what I'm trying to say is you need more leverage action and friction.

You want a larger brake disc so you get better mechanical leverage, its far easier to apply force with more leverage. Think of a wrench, using a tiny wrench on a large bolt will do nothing. When you apply something like a cheater bar it give you the ability to apply more force because your applying it further out.
If this truck was for racing or something of that nature, a larger disc brake would be extra weight, you only need what is the minimum to stop the truck. However since your adding not extra weight but are pulling stuff ( which no RC was intended for) you are going to need that extra capacity.

Friction is also a important factor in how well your brakes work. I suggested a strong servo because you can modulate how strong the servo acts on the brake pads. You would also want to find a good brake pad material that has strong cold bite and does not fade. I'm not to update on pad material for RC cars but I'm sure a little research could find a manufacture that uses a good brake material.

In the end, YOUR settings would influence how strong the brakes are, servos are not on/off type of things. What the op is doing is taking a truck and using it way different than it was designed to do, I even bet when they designed it no one even thought some one would pull kids around in a wagon with it. I personally think this project is awesome, I'm just trying to give a realistic opinion.

I love my Monster but I wish Castle would release ratings for these things. I'm glad you got it working, the max looks like a beast of an ESC.

On the brake question, you are also limited by available traction.

On it being used for a purposes for which it was designed, this one has gone through a lot of that.
(1) Started as a Nitro Revo;
(2) I converted it to an E-Revo which I used until Traxxas came out with its own E-Revo (which is awesome) and then I had to find a new use for it;
(3) so then I locked the diffs, changed gearing and added the long throw suspension kit and converted it to a Revo Crawler;
(4) and now it's a Revo Puller!
Converting from the Crawler meant not just the addition of weight for traction, but the removal of the 4:1 RC4WD gear reduction unit which was not designed for this and stripped pretty quickly. Luckily I was able to find the very low KV outrunner motors to solve that problem.

Just posted a couple of videos on youtube, showing it pulling the wagon with my 4 year old daughter in it, and also one of it pulling my neighbor's 18 year old daughter. Don't have any videos of it going up the driveway yet.

pulling a kid - http://youtu.be/RdgAwjeBuEA
pulling an adult - http://youtu.be/0Kca37TQigw

good point about the traction, I guess I was looking at like its a perfect world.

Pretty sweet, looks like it has some series grunt to it.

How low of kV are you running?

I was running 350KV on 6S, and am now running 775KV on 4S, both geared as low as I could without any type of gear reduction unit.

Are they 540 size outrunners (roughly 36x50 external)? If so, and you're happy with them, can you provide links please? I'm currently running an 870, that I'm relatively happy with, but would am interested in other options. Thanks

No problems with either. Little surprised I'm getting so much power out of them and they aren't bigger, but then again, gearing matters.

Hyperion ZS 3025 10-Turn 775Kv, 38x50
Turnigy Aerodrive SK3 - 4250-350kv Brushless Outrunner Motor, 42x58

Not sure if I'm allowed to post links to products.

As a regular member discussing items like in this thread it's no problem, go ahead. The concern is only for sales oriented posts and threads.

In that case:

http://www.allerc.com/hyperion-zs302...or-p-4597.html
and
http://www.hobbyking.com/hobbyking/s...dProduct=18170