Offset brush hog

Offset Brush Hog

Looking to mow 1-1/2 miles of trail/road with 49 8N. Mostly grass, some blackberry, some 3 mo old willows grow over this access road and like to keep it tidy. Right now it is a multi-day chore with a Stihl weed whacker (with brush blade) Ok to do some hand work but like to get the bulk with tractor.

What I think would be great is a brush hog type mower offset so it mowed 12 or 18 inches outside the rear tire. This would allow me to mow to the edge of the road, over the ditch, and in sunken areas right up to the wall. Cut the left side driving out; cut the right side driving home. Problem is I have never seen such an object…. And I’ve looked in the archives for both 8N and implements and a few google searches.

Q1 Am I missing something, is there an offset brush-hog (and less than a zillion dollars) Or perhaps a very short sickle bar mower. Don’t want the mower sticking 3 ft past the wheel.

Q2 Am I missing some critical bit of tractor operation (or more importantly safety) that makes this a terrible idea?

Q3 Is making such a creature a worse idea? A PTO gearbox, a transverse shaft to a right angle drive, all scaled for 25 hp, some blades. Whole assy mounted to a steel deck with bracing and lift points. Sure cost more to make than purchase but if it was the right thing may be worth it.

As always thanks in advance for your collective wisdom.

Flail mowers are popular with road crews and parks, so they turn up in equipment yards and auctions on a regular basis.

-John

I think I"d start with just a 4 foot hog because of the weight, which you will probably have to double to make what I am proposing. You do not want to get too heavy, or you will have lift, etc. problems. The extra weight will be from the frame needed and the counter weight needed. A counter weight is needed because you want the implement to be balanced so that its center of gravity is directly behind the center line of the tractor - side tipping safety! So that means you must put weight out the opposite side of the tractor from the side the mower is on.

Now the gear box for the mower is usually mounted with four bolts. Thus you can turn it 90 degrees so that with the mower out the side the input shaft of the mower points back to the center. Now you will need a right angle gear box to get the PTO and mower shafts to line up. I would try a differential out of a light model car. The diffy will not be one to one but that will probably be OK if you run the mower with that in mind - don"t rev up the tractor - you should not have problems with the mower running too much over rated rpms. Now that I think of it this actually this would work great with a sherman under drive where the PTO runs slower for the same engine rpm.

You will need to fabricate a suitable frame to mount the mower on. I would not want to modify the mower, except for the gear box rotation, so that you can use (or sell) the mower as it was made. The top link hook up on the mower will take some thought, maybe even make the frame attachment so that it is behind the mowers top link hitch point. Don"t forget to extend the frame well to the opposite side where you can attach weight to counter balance the mowers weight. Be SURE to design the frame so that you can lift the whole unit without hitting the tires, etc. You might want to mockup the frame in wood, easier to do and cheaper, so that you can see how it works first. The wood probably would not actually lift the mower, but you could even mock up the hitch and deck of the mower out of wood too.

Gee, I just thought of a fancier way to make the frame. Make it so that the mower can be extended for mowing or retracted for transport. The counter weigh would have to match the mower position for balance, but that just means making the same mechanism for both sides. The movement of each side would have to be adjusted for the relative weights of the mower and counter weight. A lighter counter weight would move further than a heavier mower would to maintain the balance. That is because of the torque each generates is a function of distance and weight.

Remember your high school physics, torque is weight times distance. So the weight of the mower times the distance between its center and the center of the tractor is the torque you need to match to have the two balance ecah other. So if you can extend beyond the tractor wheels on the opposite side from the mower, you will not need as much weight out there to match the torque.

Hope that will give you enough to take it from there.

Larry

Around here they aren't popular anymore, and can be had for scrap price.

My idea whoul be for you to set one tire/ rim all the way in, and then rig a long stabilizer bar on one side only to push the mower as far to the opposite side, givin the limits of spacing and mower drivetrain angle.

I bet you can get that 12" at least, that you are looking for, using a 5' mower.

Now.. if this stuf is simple stemmy stuff.. and not thick at all, and the mower is only cutting on the 'edge' and not down the middle.. I'd try to borrow a neighbors light duty 6' mower, and offset the same way... probably get you 18" on the far side, and even on the close side. With only that outer edge of the mower cutting.. the N should run the 6' mower just fine.

Soundguy