Sawyer Rob
Super Member
I don't think 1/2" hoses is big enough...
SR
SR
Hydraulic power pack build
- Thread starter truckinfouble
- Start date
- Views: 43268
Piston
Elite Member
boggen
Elite Member
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- SSTT (Sideways Snake Tain Tractor) and STB (sideways train box) tractor, dirt harvester
if you are going hydrualic. *rubs chin* wondering why you are wanting to keep the gear box.
properly sizing the motor and pump. can result in what you need. without ever needing a gear box.
check out some stuff at Surplus Center there is a lot of choices there vs other websites. might help ya figure it out. in the help section some place is some online calculators. to help ya figure out cubic inch info to figure out RPM's.
the more RPMs = less torque
the more torque = less RPMs.
540 pto pump X pressure (what ever you want) at Y cubic inches = GPM it will create at max pressure.
on the rotary cutter motor side....
blade tip speed / rpms = wanted motor RPM.
RPM and GPM get those numbers and figure out what cubic inches the the motor will need to be at.
if you were going to run it off say a 3rd function connection on FEL. you get GPM and max pressure from your tractor specs and not a PTO pump on the rear.
inside diameter of pipes and hoses matter. going to small = lots of extra friction and loss of pressure to the motor. going to large and you just waste cash. NOTE inside diameter, not outside diameter of hoses and pipes.
your pressure relief valves, can help reduce sudden shock of hitting something.
--an accumulator. can also act like a shock reducer.
--hoses themselves *meh* longer the rubber hoses. they can expand a little bit to take shock, but would not rely on it. more likely to bust a hose doing that.
--water hammering effect = google search. most of the stuff will be for homes. but might be initial learning to understanding hydraulics better.
properly sizing the motor and pump. can result in what you need. without ever needing a gear box.
check out some stuff at Surplus Center there is a lot of choices there vs other websites. might help ya figure it out. in the help section some place is some online calculators. to help ya figure out cubic inch info to figure out RPM's.
the more RPMs = less torque
the more torque = less RPMs.
540 pto pump X pressure (what ever you want) at Y cubic inches = GPM it will create at max pressure.
on the rotary cutter motor side....
blade tip speed / rpms = wanted motor RPM.
RPM and GPM get those numbers and figure out what cubic inches the the motor will need to be at.
if you were going to run it off say a 3rd function connection on FEL. you get GPM and max pressure from your tractor specs and not a PTO pump on the rear.
inside diameter of pipes and hoses matter. going to small = lots of extra friction and loss of pressure to the motor. going to large and you just waste cash. NOTE inside diameter, not outside diameter of hoses and pipes.
your pressure relief valves, can help reduce sudden shock of hitting something.
--an accumulator. can also act like a shock reducer.
--hoses themselves *meh* longer the rubber hoses. they can expand a little bit to take shock, but would not rely on it. more likely to bust a hose doing that.
--water hammering effect = google search. most of the stuff will be for homes. but might be initial learning to understanding hydraulics better.
OP
truckinfouble
Bronze Member
3/4 hoses duly noted. As far as my tractor I believe it is around 10-11 GPM available and does not have the fluid capacity I feel comfortable with keeping cool. That is why I am looking at PTO mount gear pumps. If I can find a way to use a higher flowing pump I will. If anyone knows how I could do this feel free to chime in. I know a little about hydraulic systems, but never designed one haha. As far as the direct drive VS gear box, I thought even Direct drive units went on to a torque hub which usually uses a planetary thereby making them in essence still use a gear box...
I will look deeper into cushion valves.
Also, I am doing this because it will not see commercial scale use, I have access to metal for a fair price, and most factory units are expensive.
I will look deeper into cushion valves.
Also, I am doing this because it will not see commercial scale use, I have access to metal for a fair price, and most factory units are expensive.
Xfaxman
Super Star Member
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Not sure if direct drive uses planetary gears, but I like this dual spindle Brushcat: BrushcatTM Rotary Cutter Attachment - Bobcat Company
I’m kind of in the same boat, honestly. I’ve been trying to figure out the whole “brush cutter + separate hydraulic power unit” setup myself, especially when the tractor hydraulics don’t give enough flow or pressure. I ran some numbers using a hydraulic power pack calculator I’ve been using…but I still get stuck at the same question you’re asking - once you size the pump for ~21 GPM @ 2000 psi (since that’s all the PTO HP allows), what do you actually do when most cutter motors are designed around higher pressure systems (2500–3000 psi)? It seems like hitting the required blade torque at only 2000 psi forces the flow way higher than what PTO horsepower can realistically handle.
grsthegreat
Super Star Member
My powerpack is operating at 3000 psi? On a 45 hp tractor. But my flow is 15 gpm. In order to reach 20 psi i think they told me id need a 75 hp tractor ( as i recall).