Building a hydraulic rotary mower deck

[FredBobed]

Hello-
I have a bit of a project I'm looking at. I have a toro greensmaster reel mower, and I'm thinking about converting it to a rotary mower. The mower has 3 reel units, so what I was thinking is that I could either take the 3 hydraulic motors that drive the reels and attach each one to it's own individual blade, or I could route them together into a junction, get a new, larger hydraulic motor, and use the single motor to drive a central pulley, and then just use the deck belt to drive the blades.
Also, I wonder how much HP I might need. I have the opportunity to get a 5 or 6 foot deck. The tractor has a 16 HP Kohler Magnum. Would 6 feet be a little much? The cut width with the reels is 6 foot, but perhaps reels require less power than rotary mowers?
Anyone got any suggestions or words from experience?

 

[bobodu]

Things get a little complicated here...or a lot!!
I tend to throw things together and hope for the best...for the most part...it works.I have on hand,several engines up to 20 HP,a new 4000 rpm motor and a 13 GPM pump.You will find great variances in efficency between various motors and pumps...enough that a lot of power can be wasted.A rule of thumb is that a 1 HP hydraulic motor is equal to a 1 2/3 hp engine....BUT ya gotta factor in where that hydraulic motor gets the 1 horse in the first place!! Now factor in a few horses to drive the unit along the ground.
I like to GO BIG..then figure out what to do with the tractor besides mow...like split wood!! /forums/images/graemlins/grin.gif
You can take the cheap and easy routes and call Baum Hydraulics and talk to a salesman....
I plan on building a four foot front deck mower with rear steer hydraustatic drive for the wifey next winter.Pretty sure I can get by with a 16 HP Brioggs and save the Magnum 20 for real work.. /forums/images/graemlins/shocked.gif

 

[sandman2234]

I have a Steiner 525 with a 5' deck, and bought a 6'6" reel mower (3 gang) to mow my inlaws yard. She likes a manicured yard. While I was there picking up the reel mower, the seller mentioned he had an extra one, if I wanted it for a lot less money. I bought both.
The steiners reel mowers use a hydraulic pump on the mower attachment, and is powered by the front PTO via a belt.
The drawback I see might be the speed or horsepower of the reel motors. They do not turn as fast as a rotary blade spindle (or at least appear not to) plus the horsepower rating might be less due to the small diameter of the reel, compared to the diameter of the arc of a blade mower.
I have considered making a project similiar to yours, using those motors to drive a deck like a boom mower.
Getting around to it will be the problem.
Keep us informed on how they do, and how it works.
David from jax

 

[sandman2234]

Here are some pictures of the decks.

 

[tglass]

in the process of building a hydaylic trimmer, and this is the first time in years I've heard of Baum Hydraulics. They used to be very helpful and had good price. Do you have a site address or phone number for them?

 

[keeney]

1st suggestion: sell the Greensmaster and buy the mower you really want.

Power requirements depend on what you are cutting.

The Greensmaster typically shaves a maximum of about 1/8" of very finely manicured green off per cut - not a lot of mass of grass to slow down the blades, so it can get away with a 16HP engine driving 6' of cut.

For typical lawn cutting, the rule of thumb is about 3 HP per foot of width, so a 6ft rotary deck is going to run better with a few more HP, but 16HP may be enough for many situations. Should be plenty for a 5' cut.

The motors may be close to the correct speed. A greens cutter reel has a lot of blades (typically 8 or 11), so it looks like it is spinning like crazy, but it might just be an illusion.

Most rotary decks have a single input shaft and and belts to drive the three spindles, so a single motor would be the best way to go. Just mount it directly to the deck and you won't need a belt or shaft from the tractor to the deck. The existing reel lift can probably be easily adapted to lift a front deck.

I think the greensmaster uses three seperate pump circuits for the three reels, so to switch to a single motor setup, it might be easiest to combine the three flows and size the motor appropriately.

Height of cut is probably adjustable between 1/16" to 1/4" of an inch. A High-cut kit from Toro is available to move that up to a range of about 1/4" to 1" which is useful for fairway trimming and such.

What are you going to cut with it? If its a finished lawn, I'd say just jack up the greens-cutting reels a couple of inches by extending the roller mounts and use it otherwise as-is. Probably make a very nice cut finished lawn.

It might be perhaps a little under-powered in thick grass.

- Rick

 

[tracycarr]

hi guys
i just bought a toro 3 reel mower with intentions of turning it into a deck mower
i guess i will just start with any deck i can get my hands on, see if i need to change pullyies for rpm speed, then see how the power works out.
seem using smaller decks will be worse thing to happen.

i do wonder if the side discharge (3) will be a proble.

Tracy

 

[J_J]

I know the smaller PowerTrac mower decks are driven by a hyd motor, about a 3 cu in, that turn three pulleys. Either a 48 in or a 60 in deck.

They also use a 48 in brush mower with a single spindle, swinging two blades.

The PTO about 8 GPM to the hyd motor. .

 

[tracycarr]

Wow
Thank you for that info
I did not know anything about that pc of equipment.
Just joined today and glad already.

 

[J_J]

If you want to do the less money route, then find yourself the best deck your machine can handle, and compute the hyd requirement and turn the three spindles with a single hyd motor.

The 48 in hyd deck from PT is about $1300

The 60 in hyd deck about $1500

 

[tracycarr]

Thanks again.
I looked up power trac.
They sell a 60" for there 25 hp one.
I have plenty of engine just don't know if i have enough ump at the hydr motor. There are 3 turning 30" reels each. There are 3/4 lines to them. That looks encouraging!

I can get a rpm guage or study what the reels turn at but....does any one know off hand?
Toro w/ 7 blade reels. 48 hp for some reson!

 

[Industrial Toys]

This would not be something for the faint of heart. Hydraulic motors are all about math. Flow, pressure, speed. For a rookie to get things right is a million to one shot, I would say. If time isn't an issue and you have some free stuff to play with, then it's a different story. Especially, lots and lots of free oil!

I have a Cushman 10 foot hydraulic three deck mower with a 56 horse power (or so) kubota engine and man, can that thing cut grass. The rating on a thing like that is about eighty acres a day! I had my doubts about being able to transfer power to a mower deck that way, but have since changed my mind.

But, it is so complicated and utterly blows my mind. There are valves, relief valves, case drains on the motors, very scary stuff. It's unusual not to have something leaking as "0" rings get old and they are all, almost impossible to get at with a wrench.

If you are really going to do this, remember that you are dealing with the inertia of the spindles and you can't just shut it off without providing relief. You should have some understanding of such circuits. I do not. When my valves are shut off, and all the mower decks not operating, I still get oil at pressure coming out of either side of the lines to the motors. Makes no sense to me what so ever!

 

[J_J]

Industrial Toys says:

When my valves are shut off, and all the mower decks not operating, I still get oil at pressure coming out of either side of the lines to the motors. Makes no sense to me what so ever!



What you are saying only makes sense if the spindles are still turning.

Once the spindles are stopped, no fluid should flow as the motor spool valve is in neutral and fluid is just passing through the valve.

Put a hyd gage on your deck hyd with the spindles stopped and tell me the pressure.

If you are using motor spools, you don't need a relief across the hyd deck motors.


Actually, your 56 HP engine has enough power to turn a hyd pump, putting out about 27.6 GPM at 3000 psi. So if you spread that across three decks, each deck would be developing about 12 HP, and about 12 HP for the drive.

 

[Industrial Toys]

Well, that's exactly what I figured too. But I had the same experience when I tried disconnecting the lines from the stabalizer on my Kubota R510 backhoe. Oil came out at pressure when the valves were at rest. Go figure, but it makes it hard to run the machine while parts are out for repair, without getting plugs and caps for everything which is not easy either as everything seems to be odd styles and varying sizes. I've found that the only way one could get the right fittings for almost anything hydraulic would be to have your project sitting in the parking lot of the hydraulic vendor. Especially when designing and building your own stuff.

As far as horse power goes. Don't forget the power used by the hydro and rear wheel drive motors.