Brush Hog Gearbox

[John_Mc]

Does anyone know if Brush hog gear boxes are a 1:1 reduction, or is there some speed reduction there as well? I'm looking for a cheap way to turn the PTO output 90 degrees, and hopefully slow it down at the same time. An old gearbox from a brush mower gets me the turn, but probably not the reduction?

John Mc

 

[Farmerford]

Both mine are rpm increasers. One is about 1:2 and the other is about 1.5:2. The larger single blade mowers (7') may have a slightly lower speed increase, but I doubt any will reduce speed.

Of course, a 1:2 speed increaser driven from the output shaft (where the blades attach) instead of the input shaft becomes a 2:1 speed reducer. The reverse power flow should not harm the unit since the bevel gears are unidirectional. However, almost all output shafts have a Society of Agricultural Engineers standard tapered spline for the blade hub to bolt on. You can buy the hubs separately and I suppose you could weld a 1 3/8" female 6spline on it to connect with your PTO shaft. Then you could probbably find or have made an adapter to put a male 1 3/8" 6 spline on the old input shaft (most are 1 to 1 1/4 round with a keyway or hole for a shear pin). But that seems like a lot of effort (and doesn't include figuring out how to mount it).

 

[sandman2234]

What do you have in mind to do with the reduction after you make the right turn?
David from jax

 

[John_Mc]

What do you have in mind to do with the reduction after you make the right turn?

Looking for a cheap way to make a capstan that I can use for skidding logs, and other misc. pulling duties. I can't justify the cost of a Farmi winch, or similar for the low usage I would have. Electric winches are just too slow, and duty cycle is questionable (for the winch and/or the battery/alternator on my tractor).

I've seen capstans powered by small gas engines with a rated pull of 2500#... basically just an engine (about 2.5 HP), a reducer, and a capstan. Sounds simple, but costs $1300+. I'm just kicking around ideas at this point for something cheap (used/junk parts) and with a bit more pull. If I had a top speed of around 200 FPM, I'd be happy. A 2:1 reduction driving a 4" capstan, with my tractor RPMs set around 1800 would put me in the ballpark (540 on the PTO is about 2600 on my tractor)

This whole thing may end up being more trouble than it's worth. For one, I'm not sure that most of the gearboxes I might find can stand the side load, so I may have to do something more complicated than just welding/bolting a capstan on to the output shaft of a gearbox. Then there is the matter of what to mount it to. Putting it on my boxblade is one option. That would give me something to plant into the ground so all the pull isn't directly on the tractor, and I'm not relying solely on the tractor brakes. The boxblade may need some reinforcement, and I haven't checked for how I'll get the PTO shaft to where it needs to be (boxblade isn't here now to look at).

Now that I've gotten into this, prehaps this post would have been better suited to the "Build It Yourself" section...

John Mc

 

[sandman2234]

First thing, from what I understand, the pto output doesn't follow rpm directly, so dropping XX rpms may not drop pto rpms by the same margin. Might want to check the speed of the pto at reduced rpm to be sure of the output speed. Speed indicators for rpm and surface speed really aren't that expensive if you luck into one on the fleabay like I did.
I built a capstan out of 12L14 about 15 years ago, and welded in a piece sectioned from a pto spline so that it would slip right onto the pto output. I can tell you that that was too fast for comfort for raising and lowering a weight used to drive pipe into the ground. (drilling a well) so a reduction is definitely need for your approach. I am not sure that I would tackle things the way your trying to do them. Skidding logs via a capstan will require the use of a rope, and the capstan will burn the rope as it slides around it. Plus wear and tear from the rocks, etc will also take a toll on the life of a rope. With my luck, I would get a few good pulls, then the rope would break and fly right into my ugly mug, giving me a bloody nose.
Have you considered a pto winch from an old military vehicle? I have a Bradenton that has a forward/reverse lever on it sitting out in the garage awaiting a project similar to yours, except for pulling vehicles instead of logs. It has a reduction already built into it, so that limits your need for the gearbox. If spooling the cable out is a problem with one of them, you could always use the drum as a capstan?
I never measured the speed of my capstan at idle speeds, but if it would help, (and I can find the speedometer) I could probably check it on my tractor to give you an idea, but different tractors probably have different output speeds, especially since your rpm at pto speed is a lot higher than mine.
David from jax

 

[N80]

Older trucks used to come equiped with pto powered winches, especially military (kaisers, deuce and half) trucks and jeeps. Find a used one of those and mount it on your box blade.

Here is one off a Holmes wrecker (on the auction site)

Edit: The picture won't show up. But do a search. Current bid is $150. Looks very stout. Has frame built onto it so you could probably bolt it onto the box blade. All you'd need is a little pto shaft.

 

[John_Mc]

First thing, from what I understand, the pto output doesn't follow rpm directly, so dropping XX rpms may not drop pto rpms by the same margin.

From everything I've seen, the PTO speed does directly follow engine speed. It's driven off the engine, through some gearing. Cut the engine RPM by 50%, and you cut the PTO RPM by 50%. At any rate, I'm not picky about the exact speed, I just don't want to have to run the engine at idle to get a comfortable working speed.

Skidding logs via a capstan will require the use of a rope, and the capstan will burn the rope as it slides around it. Plus wear and tear from the rocks, etc will also take a toll on the life of a rope. With my luck, I would get a few good pulls, then the rope would break and fly right into my ugly mug, giving me a bloody nose.

It was actually a Forestry Winch that gave me the idea for this in the first place. A 2.5 HP Honda engine drives a small capstan through a gear reduction, giving about 40 FPM (significantly slower than a Farmi Logging winch, but faster than most 12 V electric winches). They come with a 1/2" double braided nylon rope. At least at that speed, they don't seem too concerned about burning the rope, and I don't have to stand right near the capstan when operating it. I'm not talking about commercial usage here... if I was, I'd just buy a Farmi winch. If I can come up with something significantly cheaper than the $3250 for a Farmi 351, that would buy a lot of replacement rope.

Have you considered a pto winch from an old military vehicle? I have a Bradenton that has a forward/reverse lever on it sitting out in the garage awaiting a project similar to yours, except for pulling vehicles instead of logs. It has a reduction already built into it, so that limits your need for the gearbox. If spooling the cable out is a problem with one of them, you could always use the drum as a capstan?

That's a great idea! Do you have any idea what those things are typically geared for? Does a military truck PTO generally run about the same RPMs as a tractor? I do need it to "free spool" out. Waiting around while it powers out would slow me down to the point where I'd just go back to dragging short sections by hand.

I never measured the speed of my capstan at idle speeds, but if it would help, (and I can find the speedometer) I could probably check it on my tractor to give you an idea

I appreciate the offer, but I've got the PTO speed covered. If I did need more information, I have free access to an RPM/FPM wheel.

John Mc

 

[N80]

That's a great idea! Do you have any idea what those things are typically geared for? Does a military truck PTO generally run about the same RPMs as a tractor? I do need it to "free spool" out. Waiting around while it powers out would slow me down to the point where I'd just go back to dragging short sections by hand.

I'm 99% sure they will free spool out and I think most of them have a clutch mechanism for control. But, my knowledge on these things is very limited. I'll ask my B-I-L (he collects military vehicles and has quite a few of these winches) when I see him over Christmas. Maybe he has one he'd sell.

I have no idea how they're geared. I'll ask that too.

 

[sandman2234]

Everytime one of these winch ideas comes up, I pretty much go back to the same thing. Take a pto winch, as was suggested and add a hydraulic motor to power it. You have three main sources of power from your tractor. Instead of using the pto, use the hydraulics. The advantage of it really will provide you with a lot better service than using the pto. The major drawback of the pto is going to be inability to control the speed, and failure to be able to reverse it. A capstan will allow a certain amount of play in speed control, but not really. Kind of like having a car with the motor running wide open, and all the speed control you have is turning the key on and off. You can get good at using a capstan, but it is still a full speed when it is pulling and no speed when it is slack. There is no in between with it. A hydraulic motor on a winch will give you the speed control, and also reverse that you will need.
Too bad a pto on a tractor isn't set up like the pto on the military vehicles, so that you can use the transmission to change the speed of the pto, or reverse it. I had a pto setup for a military jeep, that mounted on the rear of one, along with the shaft and gearbox set up, but gave it to an old man here that restores military jeeps. He was pleasantly surprised with it.
David from jax

 

[Soundguy]

That was going to be my sugestion.. hyd powered motor.. etc..

soundguy