Just came from Home Depot, and I see they have a hydraulic post hole digger for rent. It's driven by a Honda engine, and mounts on a trailer-like chassis to be towed behind a truck or ATV. Now, I really can't see anything too special about it, and I'm thinking of building one to mount on the trailer ball and rear rack of the ATV, and getting rid of the trailer idea altogether. I expect the whole thing would weigh around 150 lbs. Mounting the engine and hydraulic reservoir on a skid to attach to the rack would take some of the weight off the trailer ball, and leave only the hydraulic motor, the auger and the linkage to travel it up and down behind the ATV. Any thoughts on this?

 

Just keep in mind you're putting a lot of weight up high. That can turn in to some interesting changes in handling, specifically an increased desire to roll over or flip backwards on a hill. I ride an AC 500i, a big pig of a quad. It surprised me how putting a 150 pound kid on the rear rack altered the handling. Felt okay, until I started up a hill, and found out my steering didn't work. Had to crawl up on the gas tank to get the front end to turn.

I'd stick with the trailer, and put fat off road tires on it, so it doesn't get hung up on rocks or roots. A lot of the problems people have with trailers on quads is the skinny tires that keep snagging on rocks. Fat tires just flatten out and roll over obstructions. I've pulled a trailer loaded with hardwood - probably 400-500 pounds - across some pretty rough terrain, no problem.

 

We've been thinking the same thing, although the Honda has a pretty low center of gravity, even with two people onboard. I think a T shaped frame would work well, with some gusseting for strength, and the wheels at the end of the bars of the T. Build a small platform for the engine and pump, and the reservoir. The auger and motor can go on a balance beam arrangement, pivoted over the axle. I liked the setup the machine at Home Depot had, except that you had to uncouple and pivot the whole machine to bore a hole. This way, the trailer stays connected to the quad, making it a lot less likely to grab and swing the trailer and operator et al around. Time to start pricing components and start shopping for a welder.

 

Chilly:

Keep us posted on what you find out, sounds like an excellent idea. Same machine would work great for digging holes for planting trees and bushes.

One of my projects for next winter is to build some kind of trencher to use behind the quad. Nothing new to engineer, just put it all together.

 

you might want to start by looking on Northerntool.com and look for components....I guess i find them to be fairly cheap....I suppose you will need a 3 pos 4 way lever operated detented valve, engine mabey 8hp, coupler for pump to engine, pump(possibly a gear pump for somthing cheap), motor, auger, relief valve set 10% above max operating psig, hoses mabey 1/2", fittings, return line filter, inlet strainer, resevoir (usually about the same size as pump gpm so if it's 8gpm then you want an 8 gallon resevoir or more), possibly 2 psi reducing valves one for cw and one for ccw for the motor so the motor dont try and tear the equipment apart, that should do it i think....just a start i guess but you should draw up a schematic first and go from there...ok just some suggestions for yah... but i suppose you already know what you need...