Building a engine powered 4-5ft brush hog

[db556]

Well I let my property get very overgrown, so much that my gravely walk behind(and me) just can't keep up.

I tried trimming the front and back of the deck on a cheap lawn tractor but I had to stop every few minutes to get the chainsaw out for anything over 3/4"

Last summer I dug up a 40" swisher ATV tow mower and it worked OK if I smashed things with bucket of my skid steer, (1980's New Holland L425 with no auxiliary hydraulics) but since it had a solid blade and no stump jumper it stalled out a bunch and I didn't know since I couldn't hear it, skid steer need a new muffler.

My plan is build a engine powered to push it in front of tow it behind my skid steer.

So I'm currently browsing craigslist and marketplace for no too rusty but cheap 4 or 5 ft brush hog.

Now I have some double 5/8" vbelt sheaves that if the engine is turning about 3500rpm should give me about 550rpm "PTO"

Now I thinking how big of a engine to use?

I know tractor and lawn 'tractor' HP don't really match up but at about 5hp per foot I'm guessing about 25HP or more.

So maybe a 25hp kohler command or HF predator engine, or I can dig up a 1600cc VW air cooled or Wisconsin V4D or similar either is about 26-40hp and probably high torque than the lawn tractor engines, but would be more work to either find or setup a clutch for. Where with the lawn tractor engines I can just use a go kart clutch.

Anybody have any thoughts, or have done this before?

 

[ArlyA]

I've designed a similar project and I'd add some comments over time. I like that you are using belts, which would be something to break instead of costly hard to fix parts. Are you going to used angle drive like on regular three point mowers?? I'd use an electric clutch..

 

[db556]

Finding a dual vbelt electric clutch for a 1" or greater shaft might be a problem.
If I go with the 25hp kolher engine, I was thinking of using a linear actuator to tension the belts with a idler.

I think I found a cheapish 5ft ford, sellers going to send me some more pictures.

I have a line on a single port 1600cc VW so thats about 40ish horsepower but I would need to make bearing mount and a splined shaft to mesh with the clutch and and mount for the starter motor. But if I could rig up a clutch lever that would work well.

 

[metalbender]

Funny how rare VW engines have become. I lived and breathed them for about seventeen years.

 

[quicksandfarmer]

Have you thought about using a hydraulic motor and your skid steer hydraulics?

 

[aczlan]

Have you thought about using a hydraulic motor and your skid steer hydraulics?

No aux hydraulics per post 1, therefor that isn't feasible.

Aaron Z

 

[BrokenTrack]

Anybody have any thoughts, or have done this before?

I looked at a forestry mulcher at the local agriculture show and it looked pretty simple.

It would be costly to buy the carbide inserts, but once they were installed, I think a homemade version would be just as good as a bought version.

Like you. my idea was to mount a separate engine to power the mulcher through v-belts. I would have the heavy-duty shaft counter-rotate against the fixed anvil shaft, to trap the debris, and it would be chewed off easily enough. I am not sure how much it would take on as far as sapling size goes, but probably more than a person thinks.

Kind of a simple build really, it just has to be rugged.

 

[Diggin It]

My 3' self propelled uses a 22HP RobinSubaru, and a single V belt with a manual engage lever. But the engine also powers two Peerless Hydro drives.

It'll take down anything it can get over, up to about 3" diameter. Biggest issue is that the drive won't power forward enough to push more rigid saplings over enough to get to the blades. The front lifts and wants to climb those saplings. I've wondered about attaching it to the loader arms somehow to give me more forward push and the ability to lift and adjust, but I'm not sure the loader arms are strong enough to handle any potential twist.

 

[ArlyA]

I think 25hp for a 5ft mower will be to low. Another point is as soon as people get their rough mower out, not cutting anything over 3/4 goes by the wayside. The reason I was looking at electric clutchs so as to give the operator a quick shut off down option in case they find that hidden rock or stump.

 

[aczlan]

I think 25hp for a 5ft mower will be to low. Another point is as soon as people get their rough mower out, not cutting anything over 3/4 goes by the wayside. The reason I was looking at electric clutchs so as to give the operator a quick shut off down option in case they find that hidden rock or stump.

And also way to start the mower without having to spend mass of the bush hog blades while cranking it over.
One catch, most bush hog gear boxes aren't going to be able to handle the side load of belts running off of the input shaft, so you're going to need to make up a jackshaft of some sort that then drives the gearbox.

Aaron Z

 

[ArlyA]

And also way to start the mower without having to spend mass of the bush hog blades while cranking it over.
One catch, most bush hog gear boxes aren't going to be able to handle the side load of belts running off of the input shaft, so you're going to need to make up a jackshaft of some sort that then drives the gearbox.

db556 was talking about adding belts and an actuator to that, so its effectively clutched.

 

[ruffdog]

Whatever engine is used will need a governor installed to control rpms.

 

[BrokenTrack]

He...he...he...

Do not over-think this. I had a concert on a farm last year and wanted to knock down some weeds in the deep ditches leading up to the concert event. I just used a 2x4, a generator, and an electric fan as a makeshift boom-mower.

I think the people that laugh the most are just jealous because they did not think of it first. It did work! :cool2:

 

[db556]

Thanks for all the comments, Got more pictures from the seller of the brush hog, wow that was some rust! Back to looking for another brush hog.

I know VW engine used to be everywhere I have two on the shelf right now for my baja bug, same with the vw 1.6 diesels I could get them for $100~$200 all day long a few years ago, now can find any.

Wish the skid steer had auxiliary hydraulics, I really want to make a tree shear or thumb for my bucket.
I see it could have came with it but finding a kit for a 1980's skid steer might be a bit hard.

Going by the usual 5hp pto per foot for the rotary cutter gives me 25 real horse power, but more it better.

I do have extra bearing to put on the gearbox shaft for the side load.

 

[db556]

Well, its been on the back burner till yesterday when I picked up a couple VW engines. A couple 1.6 diesels for backups for my truck and baja bug, and a $40 1.7 gas engine with a automatic.
I didn't want a radiator but for the cost I'll rig up a shield for it, Now it has the stock vw fuel injection box(or had) and I'm tearing that off and I have a holley 32/36.
I welded a mounting plate for the holley carb on the stock intake manifold, and I gutted the automatic to use the bell housing, for the starter and for a extra pulley to support the shaft.

Now the engine in its stock output is about 70hp so I'll derate that with age and a ill fited carb to 55hp how many B size vbelts would you guys run to transfer that many horse power?
I'll run the engine at about 2500 so for 540rpm I'll need about 4.75:1 I have a 19" dual vbelt sheave and 4" for the brush hog gearbox, but I have a feeling I'll need double reduction since that 19" sheave
probably won't have room between the the input flange and the desk of the brush hog.

I go to look at a 5ft woods tomorrow.

 

[db556]

Well its been a while but that 5ft woods turned out to be a rusty but repairable 5ft new idea 452 tow behind, which had been flipped around jerry rigged but the price was right.

And putting a carb on the VW engine ended up behing a pain so I bid on two engines at rogers auction a Leroi D176 which I found a bit crusty but had a nice gear reduced twin disc PTO
and a Continental Y69 off of a T50 baler that somebody put a generator on at some time. Since the leroi needed more work than the Y69 and it had electric start I though to swap over the PTO to the continental and get electric start at the same time. Well low and behold they ended up being SAE #5 and SAE#4 bell housings and differnt flywheel bolt patterns I'm going to redrill the twin disc pto flywheel once I can get back into work and access to a lathe. And get the PTO on the Y69 but not anytime soon.

But for now I went to harborfreight and got one of there predator 22hp engines, it is probably much less torque (45nm or 33ft) than the y69 continental and less cool looking I lover the look of this powerpack even though its only 16hp.

Now measuring everything I can do a single stage reduction with 3" dual vbelt centrifugal clutch and a 15.75 sheave on the brush hog gearbox. So that reduces my part counts, and I dont need a radiator.
I'm going to pickup some steel tomorrow for a dogleg tow bare and for a front caster wheel.

I'll post some progress and pictures tomorrow.

 

[Xfaxman]

Sounds interesting :thumbsup:.