Hydraulic motor powered rotary slasher

[IH_4_Me]

What do you think? Basically what I want to do is make my own hedge mower, but instead of having a flail type mulching head, I want a rotary mower on it.
A contractor down the road has a home made rotary hedge mower, but it is pto-belt driven, which is too complicated for me to attempt. It does a super job on the hedges too.
Im sick of mowing the roadside outside our place by hand, so I figure I should make something myself to go on the tractor. I am quite handy with a welder, so fabrication is not a problem. I just thought I should see first wether it is viable to run a low horsepower slasher (say 25-30hp) with a hydraulic motor?
Thoughts, comments and tips appreciated,

Glenn

 

[DocHeb]

A 25 horsepower hydraulic motor would require approximately 21.4 gpm @ 2000 psi. This is derived from the formula:

HP = f * p / 1714
where-
HP = hydraulic horsepower
f = flow, in GPM
p = pressure, in psi

A 25 hp hydraulic motor would not be cheap, some of that size are available at Surplus Center

This information obtained from a thread entitled Powering a hydraulic motor w/ the tractor remotes, with a useful post by darrenf.

 

[MossRoad]

Take a look in the Power Trac Forum for ideas... all Power Trac implements are hydraulically powered; no PTOs. I run a 4' brush hog on my PT425. The pump is rated at 8GPM @ 2500PSI. The larger units from Power Trac have larger pumps. The 4' brush hog is a brute and eats anything up to about 1.5 to 2 inches; pretty much anything that you can get under it, it will eat.

If you want to see one in operation, click on my little animated tractor in my signature... it is a link to my web page. There, in the left window, you will find a link to a videos page. Click on it and that should bring up the videos page. Scroll down and you will see videos of the 4' brush hog in action, as well as videos of my other implements. Kind of grainy, but you'll get the idea. /forums/images/graemlins/wink.gif

What's nice about hydraulically powered implements is there are no anlges to worry about like a PTO driveline... you just connect two hoses and off you go. Also, no spinning driveshaft to get entangled in. It really opens up a lot of possibilities and eliminates a lot of mechanical connections.

As for a rotary hedge trimmer... any pictures of one? It sounds kind of dangerous. While my brush hog can be lifted off the ground about 4 feet, I would never do that while it is running. That would put the blades and any flying debris about head level with the operator and could = instant death /forums/images/graemlins/shocked.gif I think I have seen some boom type devices that looked like brush hogs mounted on the end of the boom. The highway dept. uses them to keep the growth back on the county roads. They can be tilted to all sorts of angles, but they look incredibly dangerous. And they require a huge counterweight to keep the tractor level.

Good luck in your project. It sounds interesting and I'd like to see some sketches, drawings or pictures of what you have in mind.

 

[SPIKER]

Around here the gas pipeline guys have a large 30' track hoe that has a home made brush hog looking thing attached to the hoe's boom, it piviots up & down and at just about any angle you awnt ot see. but get up close and you're doomed! about 200 yards away it can toss debris! but it will make chop suiee out of 4" oaks and 8" pine in a hurry, they raise it up and litterly mow the tree down from top down!!! makes one heck of a racket and if you take a close look at the unit up close it has dents all over it and the cab had welded wire all the way around and it was beat up very badly..

Not something I would want around my tractor for sure. It was hydraulically powered too.

Blades were spring sttel and 6' wide by about 1" thick, with 36" or so fixed center and 24" free swinging blades. the center part was mounted to the hyd motor (monster sized one) and aws stacked about 4" thick at the center and smaller like a spring on an axel, to the final where the piviot point aws was only 2" thick. sandwitched bewteen 2 upper blade parts was the swinging blades. the guy said he had some blades break and others come off and you usually never find them he said! one he did see went right down into dirt abotu 2 foot to the side of the track just down ftrom the cab. he dug down 4 feet before givving up and getting a new one out. !!! Never found it either! lol.

/forums/images/graemlins/blush.gif

Mark M

 

[Renze]

Some years ago, when we were clearing some brush with a brush cutter, in a piece of land where we used to store rubbish and farm machinery, the brush cutter hit a piece of a telephone pole, i was operating while my brother was walking behind the machine to see if he saw anything in the grass.

I was looking back at the machine and at the moment i heard a bump, i saw a blade flying off, less than one foot close to my brothers leg.
We found the blade in the barn door, almost smashed through 18 mm hardwood... The barn was about 25 to 30 meter from where the blade was launched....

Since then i get mad if anyone is walking too close to my mowers... Especially on those old things with bad protection..



I have been thinking about the circle shredder too, i have a motor around. I think it's o.k. if you make a good cover, and i think it's better to use flails to sling around and chop, when you hit something serious the flail gives away, a rigid blade, especially if it's hardened steel, will break into pieces and tear your tractor tires open...



Things that i have also seen on serious cutters, like stub grinders, is a curtain of heavy vertical hanging chains. the chains will give away when you drive over it, but if something is launched from under the machine, the heaviness (mass inertia) breaks down the speed of the object.

The chain curtains will brake down the speed of allmost any flying object, to a speed that cant cause more than a small wound.


The chains

 

[RobertN]

The skidsteer folks sell hydraulic roatary cutters. Cruise around:
www.bobcat.com
www.asvi.com/rc50_attach_detail.cfm?WorkToolID=87

They are more expensive than pto driven cutters...

 

[rambler]

It will cost a lot more, & you need to find a pretty good supply of oil - you didn't mention the tractor you would be using to power it, but 8 gal at 2000psi won't do it....

--->Paul

 

[Taylortractornut]

Glenn you could make one with a smaller mower even the new ones the county uses here have a smaller motor on some of their boom mowers. To get the required GPM for the mowers they use the pto to run a shaft to the mower where a higher volume pump is on the frame. TO speed it up they use it on the 1000 rpm pto. They had one lose the 1000 pto so I made a jack shaft using pillow bearings chains and doubled the input sprocket diameter. One thin on the vales and the motor is to get a free spool valve because the flywheel/ stump jumper has so much momentum that if a regual valve is used the time it take the relif valve to open when the pto is shut off the Motor will become a pump and a regual valve will cause the pumping motor to blow he seals out of the pump and the motor or kill the hoses. The county did that on one mower. The best 2 types of motors ive seen on boom mowers are the gear pumps, and a vane. THey now make a some good higher speed piston pumps up to 2000 rpm for a little under 200 dollars. A gear pump is usually the best to use and cheaper and to me tougher. I also need to warn you about another gear motr type is an internal gear motor is alot slower they have a round housing. They are good for converting pto winches and such.
A good source for good hydraulics is behind equipment lots, they have older take offs that do for some applications for the hobby farmer. Uusally you can get them a nickel a pound. Take care Taylor Lambert