Hydraulic power pack build

[truckinfouble]

I am eventually building or buying a 60" Brush Cutter for my Mahindra 4540. Don't worry, there will be extensive safety cage work done lol. That being said I need to build a Hydraulic Power Unit for my 3 point to power the cutter since my tractor system would be insufficient. My big question is, while there are many motor options for low flow 16-21 GPM range, and Prince makes a pump that makes 21 GPM @ 2000 psi using the 32 PTO hp my tractor has available, are there any other pumps with a higher PSI or hydraulic motors that are up to mower work at the 2000 psi range? Most commercial mowers I see, even the low flow, still seem to need 3000 psi.

 

[truckinfouble]

Forgot to mention if I build the mower I am planning on the Hydraulic motor connecting to a gearbox. The rotating mass will be around 280 pounds with a tip speed of 11-14000. Any advice on pump or motor type from those experienced with hydraulics will be greatly appreciated. I have seen the Prince PTO pumps as well as one that uses a gearbox to increase PTO speed from 540 up to 1000 and a higher pressure pump.

 

[stuckmotor]

I must have missed something. Is this brush cutter to mount at the front? I don't understand why you don't just buy a rear mount brush cutter and power it with the pto. Maybe I don't understand what you mean by Brush Cutter.

 

[truckinfouble]

Yes front mount. I have a 72" for the rear that does great for small brush and grass, but I want a front mount to push into for the 30 acres that needs mowing between the planted pines. We are in a drought here and control burning in not allowed due to extreme dry conditions. By pushing in I can see better what I'm doing

 

[truckinfouble]

Baumalight mulcher MF760 on tractor loader - YouTube

 

[Farmerford]

I am rusty with pictures and this homemade attachment has been extensively modified since I built it over 10 years ago, but it may give you some ideas.

It is a 48" Bush Hog Squealer on a Kubota Grand L4330. I don't know how your tractor compares, but a 60" mower would be heavier than I would like hanging way out in front like it does. The Prince 4.9 cu in/rev pump transmits about 11 gpm to the Charlynn 4.7 cu in/rev motor; the 4330 pto is about 39 hp so I am not getting nearly the full power to the mower (perhaps 14 hp at best); the motor and pump are smaller because I originally built it for a smaller tractor. It works well enough that I probably will not upgrade until something breaks since a new pump, motor, and larger lines and fittings would be about $2,000.


Two quick pieces of advice.


Use a 48" or 54" mower at most and a lighht duty one at that to keep weight down.


Keep motor and pump about same cu in/rev so that the pump will turn at the same rpm as the pto. That way you will not need an extra speed increasing or decreasing gearbox or pulley.

Send us pictures.

 

[truckinfouble]

Thanks Farmerford. The Mahindra 4540 has a lift capacity of around 2200 pounds. I'm running a 650 pound root rake with no issue so I figure on keeping the mower around the same.

 

[stuckmotor]

Yes front mount. I have a 72" for the rear that does great for small brush and grass, but I want a front mount to push into for the 30 acres that needs mowing between the planted pines. We are in a drought here and control burning in not allowed due to extreme dry conditions. By pushing in I can see better what I'm doing

Makes sense to me. Thanks for clarifying.

 

[Rock knocker]

View attachment 509370

Oh, I see how you mounted the pump. It's a standard PTO pump, and you fixed it to the frame and used a piece of ag spline, held in place on the front by the shaft and detents. The shaft is long enough to go thru the pump and a female spline and bolt keeps the entire assembly in place.

Awesome idea.

 

[truckinfouble]

I think it is a great idea that helps hold the pump more stable. I just need to figure out which hydraulic motor to use now that will supply enough torque

 

[Xfaxman]

I am eventually building or buying a 60" Brush Cutter for my Mahindra 4540.

Since you mentioned "buy", There are several front mount brush hogs made. This is the brand that my wife uses on her Toolcat: Grace Manufacturing | Home of the Tree Terminator

But then you linked to a "mulcher", big difference from a brush hog. And big difference in price too.

 

[truckinfouble]

I know the link was to a mulcher, but the flow requirements are similar. I was showing how a hydraulic power pack on a 40 horse tractor could handle my needs. Of course a mulcher would be nice, but then again I haven't found a money tree or shipwreck haha

 

[Farmerford]

7.97 cu in CHAR-LYNN 104-1063 HYD MOTOR This is the same motor I used, except that it has a larger displacement to give roughly 540 rpm at your pump flow. It is probably overkill because it has a tapered roller bearing mounted shaft to tolerate a high side load and can work in most conditions without a separate case drain. The gear box shaft is 1 3/8" with a through hole and the motor is a 1 1/4" keyed shaft (surprise: the keyway on mine was 5/16, which is not the common 1/4 size, but is allowed by SAE). I coupled the motor to the gearbox with a chain coupling using a 1 1/4 inch bore on one sprocket and 1 3/8 bore on the other one. The 1 1/4 inch bore sprockets come only with a 1/4 inch keyway, so to match the sprocket to the motor shaft keyway I used a 1/4 key to fit the sprocket and then shimmed it with 1/16 shim stock to get a tight fit in the motor shaft keyway (It has been over 10 years with heavy use and has never given a problem.

 

[agjones]

Also check power-trac.com they make hydraulic equipment and forward mounted attachments including brush cutters from 48" up, tough, well made. Pricing is right there on the site....generally less expensive than other brands.

I'm a happy (professional) costumer and highly recommended them.

 

[truckinfouble]

I think I figured out how I'm going to build this. I'm gonna use a Dynamic gear pump that will give me a little over 21 GPM with my HP rating. A 30 gallon tank with a 25-50 GPM cooler and 10 micron filter. All this will be on a cradle I can hook up to my 3 point. I will run hoses that can be attached to my 3rd function loader lines with quick connect when running the mower or a tree saw.

 

[Xfaxman]

Sounds good, but will your 3rd function loader lines pass 21 GPM?

And how will you handle the flow when you shut off the hydraulic motor and it becomes a pump due to the inertia of the spinning blades?

 

[Piston]

How much pressure will that 21gpm pump put out? If it's the one you referenced earlier at 2,000psi, then you can expect the equivalent of 24.5hp in a perfect world with no friction loss in your lines.

In comparison to your 32 hp at the pto, you'll be losing a LOT of power. Not to mention it's going to be hydraulic hp vs mechanical hp and you will notice a huge difference.

I'd LOVE to have a front mounted mower like that, but I wouldn't give up that kind of power for it. I've often thought a skidsteer would be a good investment for front mounted implements.

Unfortunately, your very limited with such a low PTO hp to begin with.

 

[truckinfouble]

I plan on a bypass like several others have put on their mowers that will let the fluid flow one way and the motor to slow down like normal. The lines will be 1/2" and should handle flow. Pressure will be set to 2500 and PTO output changed as of this morning to 6? HP due to upgrading machine to a 5570 Mahindra

 

[Piston]

I plan on a bypass like several others have put on their mowers that will let the fluid flow one way and the motor to slow down like normal. The lines will be 1/2" and should handle flow. Pressure will be set to 2500 and PTO output changed as of this morning to 6? HP due to upgrading machine to a 5570 Mahindra

NICE!!!! Way to step it up a notch! Well in that case you should be able to run a 3,000psi pump at more than 30gpm!?!? That you can do something with!

 

[Xfaxman]

I plan on a bypass like several others have put on their mowers that will let the fluid flow one way and the motor to slow down like normal. The lines will be 1/2" and should handle flow. Pressure will be set to 2500 and PTO output changed as of this morning to 6? HP due to upgrading machine to a 5570 Mahindra

Hydraulic brush hogs have an advantage over PTO brush hogs, in that the blades are sharpened on both sides so it can cut rotating in either direction. I use normal for grass and reverse rotation for heavy brush.

Ours uses 3/4" hoses and the motor has a cushion valve built in to bring it to a stop quickly from either direction.