Home built small tow motor

Much of the equipment and storage I have in my home shop is on casters so that I can move things around when I need to. I have always just muscled things into place. However, I recently purchased a Milwaukee (K&T) 2K universal mill, and at over 6000lbs, it just is too much to push around, even on casters. So, I began to look around for a non forklift solution to moving heavy loads.

The Powerattack MYC25CC caught my attention: POWERATTACK TUGS MOVE UP TO 3 TONNE WITH EASE - YouTube

I could not locate a dealer in the US, and I figured it would be too expensive anyway, so I decided to build one.

I felt like the main problem would be finding an inexpensive worm gearbox that I could use to power the wheels. I ended up settling on an unusual solution. I decided to try a small tiller gear box I found at Snow Joe. The gearbox is part number TJ601E-29 and can be found here:
Sun-Joe-Replacement-Gear-Box-for-TJ61E-Garden-Tiller-–-TJ61E-29



If you decide to buy one of these, make sure they ship the plastic piece shown in the picture that connects the gearbox with the drive shaft. The part number for the plastic part is TJ600E-43.

Once I had the gearbox, I decided to use a Dewalt model DW130VR to power the tow motor. I wanted a variable speed drill with multiple handle mount locations to make it easy to mount the drill to a long handle/tow motor spine. I bought a factory refurbished one at CPO Outlets here:
Factory Reconditioned Dewalt DW13VR 1-2 in. - 55 RPM 9. Amp Spade Handle Drill

Finally I purchased two 5" polyurethane tired caster wheels from eBay. I removed the bearings and made bushings to fit the axle on the gearbox. I installed two 1/4" threaded pins into each bushing, and drilled holes to pin the wheels into existing holes on the gearbox axle.

After taking careful measurements of the gearbox, it was apparent that the plates I wanted to use to interface to the gearbox axle bearing housings needed to be 2" apart. With that in mind, I decided to use a 2" tubing for the handle/spine, and for the adjustable lift pin housing. I used 11ga for the handle/spine and 1/4" wall for the adjustable lift pin housing. I probably could have used a lighter gage (maybe 14ga) for the handle/spine, but 11ga was what I could readily obtain.

Here are some pictures of the handle/spine with side and back plate attached:



Here is a picture of the lift pin block and 5/8" adjustment screw:



The lift pin block was milled from a block of 1.5"x1.5"x3" mild steel.

Here is a picture of the lift pin housing:

Here are some pictures of the final assembly:



The tow motor works very well. It moves the mill about a foot every 2-4 seconds.

I will mention a few construction notes:
1) The side plates and back plate are 3/16" steel.
2) There are washers tacked to the handle/spine where a 1/2" bolt mounts the the drill to the handle/spine. One is there to space the drill out so that the plastic housing clears the handle/spine, the other is just a load spreader for the bolt head.
3) The slot in the lift pin housing is 3/4".
4) The lift pin is 7/16"
5) I used the factory "D" handle attachment knob/screw on the end of the drill because the threads were a fairly non standard metric pitch. Because I used the factory knob/screw, I had to make the spacer that you can see in the picture. You can also see a mounting plate to tie the back of the drill into the handle/spine.
6) The drive axle is a piece of 3/8" CRS machined on one end to interface with the plastic interface connector on the gearbox.
7) Unless you want to machine the wheel thickness, the bolts used to pin the wheels to the gearbox axle need to have the heads removed on one side so that the bolt is right up against the wheel hub.

Total cost for this build was about $200.

The drill can be removed and used as a drill in just a minute or two by removing the 1/2" bolt and the factory knob/screw and then taking the drive shaft out of the chuck.

This is first class, Neil. One more project on my build bucket list.

Thanks for sharing!

Remember that this only for light loads. The gear box is not designed for heavy duty.

Tom

Yes, my tow motor uses a light gearbox. It was made for an electric tiller with about 1.5hp. It is handling about 3.25 tons though. It may not last, but I think it will last longer than I need it. If someone wants a more capable unit, they just need a better gearbox. If they want to pursue the tiller idea, they should be able to get a used tiller from Craigslist or find one on the side of the road. The gearboxes on a 5hp tiller should rival the gearboxes on the MYC25CC. More wheels might also be desirable.

A little disappointed ....

I got to see the tow motor last week.

It wouldn't run fast enough to burn the rubber off the wheels, leaving marks on concrete, and no competition in a drag race. Definitely the Tortoise in a race.

However, easily pushed and pulled the big horizontal K&T mill.

For the $$$ invested, and design considerations the tow motor should last as long as needed. If it fails, will evaluate the failure, and deem if improvements are dictated, or just replace failed parts.

That is what we machinist do!

Ray