I built a trailer mover out of a hand truck, a 2000lb worm gear winch, a chain drive and a hitch mount. I saw commercial models that go for $1500, but I thought they looked like overkill for what I wanted.
I got a hand truck with a solid axle, and welded one of the wheels solid to the axle - put a chain drive from a 2000lb worm winch to the axle, and welded on a hitch mount so I could interchange a tow bar for different ball sizes.
I also put a third castering wheel with a locking mechanism on the back of the hitch mount so that when you lean it back it sits on three wheels and the hitch mount is horizontal.
I wanted to move my boat trailer and my 6x12 box trailer around without hitching it to the truck. The box trailer fits into my garage with about 1 inch on both sides and on top to spare, and it's very difficult to fit it in there with a truck. Good news is this thing makes that job a lot easier.
I drive the winch with my Milwaukee V28 drill. I wanted to do this, because I didn't want a cord or another 12volt car battery sitting around to maintain. The drill has plenty of power because the winch is 15:1 reducition, and I further reduce it, 3:1 with the chain, so if I run my drill in low range at 400 RPM that means the wheels turn at less than 10 rpm - at about 1 foot diameter for the wheels, the maximum moving speed is about 30 feet per minute.
OK, so here are the things I learned:
1. That Harbour Freight 2000 pound worm winch you were thinking of using is total junk. First the bearings were so loose, that the gears would slip. Then when I fixed that, and got everything installed, I found out the gears aren't hardened, and they grind each other to dust under load. I bought a Thern lubed gear winch that I'm going to replace it with off Ebay, but it seems almost too nice to cut up an use in this application.
2. The geartrain works like a charm - the drill has plenty of power and can move my trailers all over the driveway - On flat ground - I found out the unit simply doesn't have enough weight to get traction to pull the trailers up any kind of grade at all - this was a disappointment. I was hoping to move my trailer down a slight grade that I can't back my truck down - no way.
3. I built an extension out of a 1/2 inch steel rod to route power to the winch, mounted on the base of the hand truck, from near the handle. I just chuck the drill onto the rod (I ground a triangle on the end of the rod) and I can run the drill with one hand easily while guiding it with the other hand. At 400 RPM, every little defect in my driveshaft shows up, and vibrates the whole thing.
4. Originally I planned on welding only 1 wheel on the hand truck solid to the axle, so I could have the other to freewheel so I could turn it. It turns out that the torque to that single wheel was a lot, and I couldn't hold it straight - I ended up welding both wheels solid, which fixes the torque steer issue, but now steering it at all is a lot of work.
5. The hand truck idea was a good one, because it inherently has plenty of strength for the tongue weight, and I wanted it to be able to stand up vertically without taking up much storage room However there are a couple of problems. First I wanted to be able to pick up the trailer by laying the hand truck back, thus raising the ball into the hitch. There is a bit of a geometry trick, in that you want the ball center placed so the center of gravity is behind the main wheels. This means the truck needs to lay back at least at a 45 degree angle.
The second problem is that even with the truck laying back at about a 45 degree angle, the frame of it still interferes with the hitch triangle when you try to turn sharply - shallow turns are fine, but you really want to beable to turn 90 degrees or even more.
Ideally you would design it with a flat truck bed type base with the handle and drive switches sticking out well behind the location of the hitch.
If I were doing it over again - I would: 1. use a much higher quality winch from the start. 2. design the base differently for easier turning (I'll probably modify mine somewhat - but I don't want to lose the simplicity of the drill motor powering it - that works really well. I even tried moving the trailers with my Milwaukee M12 driver, and it moved my 1200lb boat trailer fine.
In the end, I'm not sure I will bother to do much more than fix this one because I had hoped to be able to pull the trailers up the hill in my driveway with it, and that simply isn't going to happen. It does work great for pulling the box trailer in and out of the garage, and it would work great for pulling an airplane in and out of a hangar.
More recently, I saw and copied a trailer mover for a forklift. I made one fo those also, and it works like gangbusters - problem is, I don't have a forklift at home, and even so I couldn't use it to move anything up any kind of grade. One of those Mini skid steers would be the ideal trailer mover.
