Hydraulic expert out there?

[brassspike]

I am working on building a small ditchbank mower for my 2350. Mower will be about 30". I need to find someone that can give me advice on the proper size and type of pto pump, hose size, and drive motor for the blade. Since this is smaller than anything currently available, I have nothing to go by. Any suggestions are appreciated.

 

[kennyd]

There are a couple threads that may help. Like THIS one.

Search "bank+mower" for some more...

 

[brassspike]

There are a couple threads that may help. Like THIS one.

Search "bank+mower" for some more...

Yes there is some good info there but that one is a bit bigger than what I need. I need to keep things pretty small. I guess I could go to the tractor dealer, measure his mower and scale his pump and motor down to my size?

 

[brassspike]

Yes there is some good info there but that one is a bit bigger than what I need. I need to keep things pretty small. I guess I could go to the tractor dealer, measure his mower and scale his pump and motor down to my size?

BTW, was that one ever finished?

 

[Mith]

try Machine Builders Network, there are a couple of threads about pump and motor sizing

 

[keeney]

For a finish mower, I know that a good rule of thumb would be 2HP per foot of cutting width, so your 30" mower would need at least 5 HP to run it which is something like 5 GPM at 2400 PSI (very rough guess).

A complete circuit of hydraulic pump, motor, and hoses can add up to a bit of power loss, so be sure and do the efficiency calculations to make sure you start out with enough pressure and flow to end up with enough power at the blade.

For sustained hydraulic power dissapation like that, you will want to be sure to include an oil cooler in the circuit at well.

- Rick

 

[brassspike]

Thanks Rick, I've pretty much decided on a design. Still have not found what pump etc. it will take. Looks like I'll have to do some salvage yard shopping this spring.
Bill

 

[Harry c]

If I understand, you want to drive this mower with a PTO driven hydraulic pump and a hydraulic motor on the mower...
Most push type lawn mowers run at 3,600 rpm and of course directly drive the blade. To get the same blade tip speed with a 30" blade as a 22" blade at 3,600 rpm you'll need to run about 2,640 rpm. The size of the pto pump you use does not matter as long as you have the matched size Hyd motor to achieve the desired speed. The pump will be rated in gallons per minute, the motor most likely will specify cubic inches or cubic centimeters per revolution. One gallon is 231 cubic inches. An 11 gpm PTO pump is fairly common. To hit the required 2,640 rpm with that pump, you'll need a hydraulic motor that uses .96 cu in per rev. Pressure depends on resistance. If its spinning free you will have very little pressure. If it jams on a rock the pressure will go as high as the relief valve setting. Make sure you have a relief valve. You have lots of Hp available. If you find a larger / smaller pump you'll need to size the hydraulic motor appropriately. You can just use percentages of the above to scale up or down.

 

[brassspike]

If I understand, you want to drive this mower with a PTO driven hydraulic pump and a hydraulic motor on the mower...
Most push type lawn mowers run at 3,600 rpm and of course directly drive the blade. To get the same blade tip speed with a 30" blade as a 22" blade at 3,600 rpm you'll need to run about 2,640 rpm. The size of the pto pump you use does not matter as long as you have the matched size Hyd motor to achieve the desired speed. The pump will be rated in gallons per minute, the motor most likely will specify cubic inches or cubic centimeters per revolution. One gallon is 231 cubic inches. An 11 gpm PTO pump is fairly common. To hit the required 2,640 rpm with that pump, you'll need a hydraulic motor that uses .96 cu in per rev. Pressure depends on resistance. If its spinning free you will have very little pressure. If it jams on a rock the pressure will go as high as the relief valve setting. Make sure you have a relief valve. You have lots of Hp available. If you find a larger / smaller pump you'll need to size the hydraulic motor appropriately. You can just use percentages of the above to scale up or down.

Thank You!! That is what I am looking for!! Although I will not be doing "finish" mowing, this should work fine.
Again THANKS!
Bill

 

[diyDave]

If you are looking for a good source of hydraulic parts, try Surpluscenter.com, they have pages and pages of pumps, motors, valves, and good tech support(they have a page with all the formulas you will need to select the correct size). Good luck, and remember to over build is better than regretting cheap components!