Brush Hog conversion from PTO to Hydraulic

[cnat]

I am currently converting a PTO 5 King Kutter Brush Hog (agri gear box) to hydraulic to run off my T200 Bobcat skid steer. The problem I am experiencing is attempting to identify the torque necessary to turn the brush hog at a certain RPM. I called Supply Surplus and this is the only answer I cannot provide to them so they can match a hydro motor for my application. I have read numerous threads referencing GPM, PSI, and PTO RPM, but nothing specific to torque. Any help would be greatly appreciated.

Thank you

 

[DuckSlayer1017]

Here is a torque to hp converter. Take the hp rating for the cutter and get the torque from the calculator.

Horsepower & Torque Calculator | Spicer Parts

 

[cnat]

Thanks for the reply. I believe I have a 40hp gear box for the cutter. Should the engine RPM be the standard 540? Again, thanks for the help!

 

[DuckSlayer1017]

If you are adding a hydraulic motor to the input shaft on the gear box then try to get one that is around 540. A little variation will probably be ok.

 

[Farmerford]

I have done the same thing and found that the controlling factor is the need to turn the mower gearbox input shaft at the 540 rpm (or thereabouts) it was designed for. Once you determine the gallons per minute that will flow to the motor you can then easily determine the size of the motor (cubic inches per revolution) that will turn at 540 rpm. The torque and horsepower transmitted to the gear box in put shaft are a function of pressure (which I assume is practically unchangeable-at least it is not increasable) and gpm, which is determined by your loader pump.

 

[Rustyiron]

Don't expect to have tractor driveshaft performance, I have an "ambusher" mower, (factory) built for a SS. It's works well but just not the same "umpff" that you get mechanically coupled to a tractor. I'd hate to try to mow a field with it but for beating back tall brush & saplings, dropping it down from 4-5' up is very effective. I'm sure you've seen it but Surplus center has a motor with a std 6 spline pto shaft that I would think would work providing it will handle the pretty high psi that SS's deliver. My ss is above 3500psi and iirc about 28 gpm on the low/std flow side.

 

[Groo]

match your flow to create between 500 and 600 rpm from the motor

 

[MossRoad]

Check out the hydraulic PTO shaft motors at Surplus Center. They may be what you need. Designed for the task....

9.59 CU IN PTO DRIVE MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com

 

[Xfaxman]

And don't forget the cushion valve: 3/4 NPT 3 GPM 15-3 PSI HYD CUSHION VALVE | Relief & Cushion Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com

 

[MossRoad]

A bargain at twice the price! :laughing:

 

[Xfaxman]

Yep, mine is built into the motor.

 

[MossRoad]

I'm not sure what mine uses, if any. I know I have to idle the engine back before engaging the hydraulic PTO diverter valve to minimize the THUD! WHAM! of the mower or brush cutter blades if I flick the switch at higher engine RPMs.

 

[TractorGuy]

Why not replace the gearbox with a hydraulic motor instead of driving the gearbox with one?

Have you read this thread in land clearing? http://www.tractorbynet.com/forums/land-clearing-equipment/375089-fel-road-maintenance-cutter.html
It goes on a ways before the MFG of the unit being discussed chimes in with details.

 

[Todd727]

Why not replace the gearbox with a hydraulic motor instead of driving the gearbox with one?

Have you read this thread in land clearing? http://www.tractorbynet.com/forums/land-clearing-equipment/375089-fel-road-maintenance-cutter.html
It goes on a ways before the MFG of the unit being discussed chimes in with details.

He needs to add a spindle between the motor and the blade carrier. It's just much simpler and cheaper for him to connect the motor to the existing gearbox. I've been down this road.

 

[TractorGuy]

He needs to add a spindle between the motor and the blade carrier. It's just much simpler and cheaper for him to connect the motor to the existing gearbox. I've been down this road.

I overlooked that. I was thinking they bolted the blade holder directly to the motor but I see now that is not the case.

 

[piaffepony]

Well crap. I came here to ask about this very thing and I'm reading the replies and it's like trying to read IKEA instructions in Korean.

I had to trade in my JD5055 for a NH175 Skid when I got divorced (I use it more and X got my skid in the divorce). I still have the 7' mower that we bought with the tractor and was curious how much it would cost and what it would take to convert from PTO to Hydraulic so I could attempt to maintain some of the larger patches of weeds that the horses don't eat and are too much to handle for my zero turn. Did I mention I have 62 acres and 30 horses to maintain as a single mom?

My question is.. how much time and $$$ are you budgeting for this conversion project? My brother is a professional mechanic and I can handle some fabrication... have you found any good resources on HOW to accomplish this exactly? As in something that breaks it down Barney style for novice diy females like myself? I'm trying to figure out if it's worth the time and effort or if I need to just sell a kidney and buy one.

 

[aczlan]

The first things you need to know are how much flow you have and what pressure it is at.
This is an L175 skid steer? If so, per New Holland L175 Skid Steer Loader it has a 17GPM pump and it puts out 2600PSI.
Take that information and go to Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com and find a motor that is rated for that pressure and flow.
Based on the above, I would use a motor such as 7.63 CU IN PTO DRIVE MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com it will also need a mounting bracket such as SAE A 2-BOLT CAST IRON PUMP & MOTOR FOOT MOUNT | Foot Mounts | Hydraulic Pump Mounts | Hydraulic Pumps | Hydraulics | www.surpluscenter.com and a bypass valve (to let the bushhog spin down when you shut off the hydraulics): 3/4 NPT 3 GPM 15-3 PSI HYD CUSHION VALVE | Relief & Cushion Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com
You will also need fittings and hoses, all in all, Surplus Center has everything for around $535 shipped, here are the PNs that I would use:

QTY	Item No.	Description	Price Each	In Stock	Extended Price
1	9-7368-125	7.63 CU IN PTO DRIVE MOTOR	$269.95	Yes	$269.95
1	9-HB-A	SAE A 2-BOLT CAST IRON PUMP & MOTOR FOOT MOUNT	$63.80	No	$63.80
2	9-2503-12-12	JIC 12M x 3/4 NPTM 45 ELBOW	$3.65	Yes	$7.30
1	9-4019-75-H	3/4 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE	$74.20	Yes	$74.20
2	9-6900-10-12	SAE 10M x 3/4 NPTF SWIVEL	$3.69	Yes	$7.38
2	9-078-12	3/4"x12" 3/4 NPTM x 3/4 NPTM SAE 100R16 Hydraulic Hose Assembly 3000 PSI	$11.95	Yes	$23.90
2	9-078-60	3/4"x60" 3/4 NPTM x 3/4 NPTM SAE 100R16 Hydraulic Hose Assembly 3000 PSI	$25.95	Yes	$51.90

Subtotal:

$498.43

That motor would connect to the tractor end of the PTO shaft, you would also need to reinforce the deck to mount the motor to it (or mount it to the plate on the skidsteer side.
You will also need a way to mount the bush hog on the skidsteer quick attach and the hydraulic quick connectors to tie the hydraulics in.

Aaron Z

 

[Todd727]

So, on top of the parts Aaron listed, you will need this:

Titan 3/8" Quick Tach Attachment Mount Plate Skidsteer bobcat kubota (38 MP)

Then you'll need to round up some scrap steel to reinforce as Aaron mentioned. You will have to weld or bolt the deck to the above plate. You may be able to use some of the 3-point bracing to strengthen the deck and attach everything to the mount plate.

I just did all of what you are talking about. Too bad you aren't closer, it really only takes about a day to get it all put together.

 

[TractorGuy]

Well crap. I came here to ask about this very thing and I'm reading the replies and it's like trying to read IKEA instructions in Korean.

I had to trade in my JD5055 for a NH175 Skid when I got divorced (I use it more and X got my skid in the divorce). I still have the 7' mower that we bought with the tractor and was curious how much it would cost and what it would take to convert from PTO to Hydraulic so I could attempt to maintain some of the larger patches of weeds that the horses don't eat and are too much to handle for my zero turn. Did I mention I have 62 acres and 30 horses to maintain as a single mom?

My question is.. how much time and $$$ are you budgeting for this conversion project? My brother is a professional mechanic and I can handle some fabrication... have you found any good resources on HOW to accomplish this exactly? As in something that breaks it down Barney style for novice diy females like myself? I'm trying to figure out if it's worth the time and effort or if I need to just sell a kidney and buy one.

Here is a 6' mower for less than 3 grand. Might be worth it to sell your tractor model and just buy one?

This is a ebay pic for a rough looking mower that looks like it may be a home conversion. Could be useful for fabrication ideas.

 

[Cord]

So your machine comes in two versions. Standard flow is 20gpm and high flow is 32gpm. Pressure is 3,000psi. The mower will work best on high flow so hopefully you have it.

Assuming you have standard flow, here are some options:
9.59 CU IN PTO DRIVE MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com
7.2 cu in DYNAMIC BMRS125H2KS HYD MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com
7.63 cu in DYNAMIC BMS125E2GS HYD MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com
8. cu in CHAR-LYNN 14-139 HYD MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com
8. cu in CHAR-LYNN 14-163 HYD MOTOR | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com
http://www.surpluscenter.com/Hydrau...n-DYNAMIC-BMS160E2GS-HYD-MOTOR-9-7081-160.axd
http://www.surpluscenter.com/Hydrau...n-DYNAMIC-BMS160E2KS-HYD-MOTOR-9-7080-160.axd
http://www.surpluscenter.com/Hydrau...n-CHAR-LYNN-104-1040-HYD-MOTOR-9-072-1040.axd
http://www.surpluscenter.com/Hydrau...n-CHAR-LYNN-104-1064-HYD-MOTOR-9-072-1064.axd
http://www.surpluscenter.com/Hydrau...n-CHAR-LYNN-104-1041-HYD-MOTOR-9-072-1041.axd
http://www.surpluscenter.com/Hydrau...n-CHAR-LYNN-104-1065-HYD-MOTOR-9-072-1065.axd

You'll need a flex coupling between the gear box and the motor. A bearing supply store is your best option, but McMaster also has a good selection. Just watch the rpm and torque rating. I'd recommend not rigidly mounting the mower to the skid steer because you'll have problems getting to follow the ground. The best install that I've seen used the 3pt hitch mounts and then had three arms coming off a skid steer plate. A chain limits the fall of the mower.