Would this motor work for a stump grinder

[woodlandfarms]

Thanks to everyone on this. It is winter project I am looking into, so starting to formulate a strategy.

I was into the heavy blade, big nasty teeth cause I thought I had a lot (18GPM at 3000PSI) of hydraulic to push things around. But now I am not too sure. Johns mention of the Praxis system makes me wonder if I am going in the wrong direction, and also if my Hydraulics are all that big enough to move lets say a 24" blade with big ugly teeth...

Opinions are really ,really welcome at this point (and at any point).

All the best

Carl

 

[J_J]

So JJ. You agree with John that isolating the motor from the blade would be better thing than direct drive like the PT?

Carl

Carl, I would think that a more heavy duty hydraulic motor, with a taper shaft or a straight shaft, directly coupled to the wheel and blades would work. If you choose to use belts and pulleys, there may still be enough force to twist that 5/8 shaft off. A lot of stump grinders, use belts and pulleys, but the engine is usually a 25 hp Kohler or Onan. I would think one of the wheel motors might work. They have a tapered shaft, and if you can find a tapered hub, It just might work. Surplus hydraulics has both the motors and hubs. You may have to drill some extra holes. Good sharp teeth is what does the cutting. If you check around, there are many different types of teeth. You have a large choice. On the valve that you select to control the motor, you want to select a valve that will allow the motor and wheel to coast to a stop. I am not sure if the PTO switch on your machine is abruptly on, and abruptly off.

 

[J_J]

Thanks to everyone on this. It is winter project I am looking into, so starting to formulate a strategy.

I was into the heavy blade, big nasty teeth cause I thought I had a lot (18GPM at 3000PSI) of hydraulic to push things around. But now I am not too sure. Johns mention of the Praxis system makes me wonder if I am going in the wrong direction, and also if my Hydraulics are all that big enough to move lets say a 24" blade with big ugly teeth...

Opinions are really ,really welcome at this point (and at any point).

All the best

Carl

Carl, You have the power with your GPM's, and psi. You could probably turn two of those Praxis cutting heads. Check out these teeth.

 

[woodlandfarms]

JJ. Thanks for the insight. OK... I am thinking hard about those blades, I have that feeling that 18GPM at 3000PSI is not going to spin my 30" X 1" with carbide tips blade.... (Am I wrong on this?).

As for control, you have thrown me for a loop. I thought that the Powertrac Stump Grinder hooked to the PTO output. Is this not the case?

When I run my mower it takes forever for the blades to shut down so I assumed this circuit would work.

When I look at Surplus center, they mention Cubic Inches. What does this mean to me? Right now I am looking for a motor that has about 800 - 1000 RPM that can take 18GPM and 3000 PSI and has at least a 1" shaft? This assumes i am running direct drive...

Thanks for the guidance....

 

[sandman2234]

I know it is just more moving parts, but I would use and idler shaft to mount the blade on, and double belt pulley's to run them. That is the way the hydraulic motor turns my flail mower on the Turner boom mower. Using sheeves instead of direct drive gives you the ability to control the speed if the motor you get is too slow, or gear it down if the motor is just a little underpowered. Since all of this is experimental it would help to be able to change a few things at minimal cost. If you really mess up, using a sheave would allow you to add another hydraulic motor to increase the power.
Not sure exactly what you have in mind, but have you considered that since this thing is going to stick out in front of your PT, if you make it to where you can turn the blade horizontal and vertical, then you can stick it into those blackberry bushes and really make a mess out of them! A cylinder or just a bolt arrangement would allow it to turn sideways without too much trouble.
I really should go by J_J's and look at his PT to get a better idea of what your up against.
David from jax

 

[JohninCT]

I have that feeling that 18GPM at 3000PSI is not going to spin my 30" X 1" with carbide tips blade.... (Am I wrong on this?).

When I look at Surplus center, they mention Cubic Inches. What does this mean to me? Right now I am looking for a motor that has about 800 - 1000 RPM that can take 18GPM and 3000 PSI and has at least a 1" shaft? This assumes i am running direct drive...

18 GPM at 3000 psi is a pretty good amount of hydraulic flow and pressure and should have no problem spinning a large wheel cutter (The PT stump cutter has a good sized wheel on it).

The number of cubic inches mentioned is the cubic inches (displacement) per revoution of motor. This will determine your motor speed. Convert cubic inches to gallons (or vice versa). I use this handy little converter program which is free.

Convert @ joshmadison.com

divide your hydraulic flow by motor displacement to determine the speed (RPMs)

For example a 3 cu in/rev motor has .013 gal/rev
you have 18 gal/min flow so,
18/.013 =1384 RPMs approximately. Hyd motors will have some amount of inefficiency so not all flow will be converted to rotation but this will give you an idea of the speed.

This site has some info and formulas that might be of interest to you.
http://www.hydraulicsupermarket.com/upload/db_documents_doc_9.pdf

Look for a motor that gives you the highest torque in the RPM range you are interested in. The wheel motors suggested are a good place to start.

 

[woodlandfarms]

Will indeed look at wheel motors, but when I see the specs they say 100 RPM... From what I have read it looks like these grinders run at 800 to 1000 RPM's.

Thanks for all the great info BTW, everything is starting to become less of a mystery...

 

[J_J]

Will indeed look at wheel motors, but when I see the specs they say 100 RPM... From what I have read it looks like these grinders run at 800 to 1000 RPM's.

Thanks for all the great info BTW, everything is starting to become less of a mystery...

Carl, Check out this wheel motor. It has rpm's in the 300, and the GPM is about right. I think what a lot of stump grinders are trying to do, is to get a velocity if feet per second that will give a decent cut. This can be achieved by a larger wheel, a certain number of teeth, or by appropriate pulley and belt ratios. The number of teeth on the blade also has to do with the smoothness of the cut.

Usually in dealing with hydraulics, the larger cu in motors will have a lower rpm. If you see a hydraulic motor running over 1500 rpm, you can bet that it is a small cu in motor like on a hydraulic pole pruner like the tree service people use.

I didn't mean to give you any doubt about your PTO circuit. On mine, I have a lever which I flip up to cut the PTO on, and adjust speed. I have an older 1445. My stump grinder/trencher, has a large hyd motor, turning a 26 in blade, with about 20 carbide teeth, My PTO pump puts out 13 GPM. I would not recommend getting the largest hyd motor you can find, you might not be able to get it up to the rpm stated for the motor. The motor will take every thing you are giving it and run at some rpm dictated by the GPM's.

Some PT owners have reversed their blades to keep debris from being slung back at them. My blade is not reversible, and I like it that way. Some of the blades have replaceable teeth, mine are welded in place, but can be sharpened. Good luck in your endeavor.

 

[sandman2234]

J_J,
Any chance you have a picture of your stump grinder. I know I probably saw it over at your house, but am lost for what it should look like.
David from jax

 

[woodlandfarms]

JJ - No link but I get what you are thinking. What confuses me is that I thought the PT blade spun pretty fast (like 1000 RPMS in direct drive mode). Am I wrong?

David...

Here are a few links I found for pix...

http://power-trac.com/images05/T12 Attachments/stump-grinder.jpg

http://www.tractorbynet.com/forums/...-pt-1850-used-stump-grinder-stump-grinder.jpg

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