Hydraulic pump sizing questions

[Wannaspeed]

So I started a thread the other day in the Massey section, maybe the wrong section for the questions asked since I have no replies. That thread is here.

Anyway I have a MF 30B industrial with loader without PTO. According to this, my tractor flows 19 GPM.

I was thinking of using a diverter to tap into the dump/curl lines of my loader and adding some rear remotes. In addition I was thinking of either converting a brush hog to run off a hydraulic motor, or mounting a hydraulic motor with a PTO shaft to connect a normal brush hog.

I found some calculations for hydraulic motor size: Fluid Motor Speed from GPM Input: 231 x GPM Fluid Motor Displacement

Based on my 19 GPM and to get a shaft speed of 540 RPMS I would need a motor that's 8.13 Cubic inch.

This is where I could start using some advice from people that have more experience.

I suspect that 19GPM is maximum flow, without any efficiency losses, or losses through controls and hoses? Using a loss of 20% (?) gives me the number 15.2 GPM and a motor size of 6.5 CI. There isn't any kind of built in restriction at the dump curl that would cause it to have lower flow is there? As you can see I don't really have any constants, the best I can do is take a guess..But if I'm going to guess I want it to at least be an educated guess. Any help would be appreciated.

Here's one of the motors I was considering.
What do ya'll think? Will it work? According to the first site my tractors hydraulic psi is 2500, that pump says:
"Pressure:
2576 PSI cont.
3091 PSI int."

But I imagine it will still work at 76 psi lower? It also says:
Flow: 19.7 GPM cont.
23.6 GPM int.

But I imagine it will still work at lower flow just at a reduced RPM? And lastly it says:
Speed:
600 RPM cont.
720 RPM int.

But given lower flow it would spin slower correct? At 19 GPM I calculated 575RPM and with my made up number of 15.2 I get 460 RPM. I think these RPM ranges would be about right... unless I'm missing something major like a restriction that cuts my flow in half or something... What do ya'll think? Any advice? Thanks.

 

[topbuilder]

My first thought is cooling. All machines I'm thinking of that power continuous volume hydraulic motors are prepared to cool the heat generated. My second thought is why use a driveline? Hook the motor directly to the gearbox. And my third thought is most of the industrial pto deletes have AG roots and the ability to power a pto if you were to acquire the parts. Possibly that would be a more cost effective route than a one off hydraulic brush cutter. Good luck!

 

[Wannaspeed]

My first thought is cooling. All machines I'm thinking of that power continuous volume hydraulic motors are prepared to cool the heat generated. My second thought is why use a driveline? Hook the motor directly to the gearbox. And my third thought is most of the industrial pto deletes have AG roots and the ability to power a pto if you were to acquire the parts. Possibly that would be a more cost effective route than a one off hydraulic brush cutter. Good luck!

Yeah I was wondering about the heat too. There's a lot more going on with a constantly spinning pump compared to a couple cylinders moving back and forth, but I wasn't sure how much heat was really generated? I have 3 acres to mow, idk if running for an hr would be long enough for heat to be an issue or if a cooling system would have to be added. If the latter I would just scrap the idea. I know the backhoe version has additional cooling, but I don't think the loader version does.

I actually considered connecting the motor directly to the bush hog gearbox in my original plan. I've seen it done that way for skid steers, but then I thought if I wanted a tiller or post hole digger in the future it would be nice to just have the PTO shaft.

Just adding a normal PTO is the first thing I looked into. I found 3 or 4 threads of people wanting to add PTO, But no one starting the topic ever indicated they ever tried and went through with it. The threads always end without much information. Some people suggested splitting the tractor would be necessary. One guy said he had it done to their 40 industrial but didn't actually do it themselves. Here's one such thread. And another http://www.tractorbynet.com/forums/...age/336256-adding-installing-pto-mf-35-a.html

From the outside it looks like it would be as simple as removing a cover plate and adding the shaft. Could it be that simple? I have the instant reverse trans. From the brief research I've done, It seems as though it might be doable and I would actually prefer doing it this way. I have the instant reverse transmission. Apparently with this transmission the PTO will spin backwards when in reverse which warrants the need for an ORC. I do already have the 3 point, it will raise while out of gear, but the forward or reverse lever has to be pushed down and the RPMS brought up. Thanks for bringing this up, this is really the way I would prefer. I think ill see if I can find more information in adding the PTO, and if I come up empty start another thread. I think the main thing is figuring out what parts are actually needed.

 

[Jabonee]

No PTO kit available from MF? Most tractors have that option and are PTO ready. :confused3:

 

[Wannaspeed]

Idk mine is a 1980 model. I don't think most the industrials had a PTO, but I'm trying to find Information on adding it.

 

[topbuilder]

No easy fix. Now that I think about it, you probably have a one stage clutch...(or no clutch?) If so, you may have to split it in two places to get the shaft in and install a two stage clutch. Pretty sure we are talking about a change that exceeds the value of the tractor.

 

[Wannaspeed]

I don't think it's that involved. I've read threads of other people that had it done, but they had someone else do it so didn't know the exact process, splitting the tractor wasn't necessary according to them. But the information isn't readily available either so I'm not sure.

The only thing with the shuttle shift is the PTO spins backwards when going in reverse, that and you have to step on the pedal to engage it. I believe that's the limitations. Without the 3pt it's apparently more involved, but I have that so maybe it won't be too bad if I can get accurate information.

 

[topbuilder]

I don't know that my PTO has ever been engaged. It has been a box blade only tractor it's whole life. That reverse PTO thing could be a bad thing to learn on the job!

 

[Wannaspeed]

I don't know that my PTO has ever been engaged. It has been a box blade only tractor it's whole life. That reverse PTO thing could be a bad thing to learn on the job!

Yeah could tear some implements up not knowing it. An ORC attached to the spline is whats recommended to protect the equipment.

 

[Wannaspeed]

No easy fix. Now that I think about it, you probably have a one stage clutch...(or no clutch?) If so, you may have to split it in two places to get the shaft in and install a two stage clutch. Pretty sure we are talking about a change that exceeds the value of the tractor.

I was reading some information on big deans cd. And it indicated that some of the instant reverse tractors did come with PTO. I also learned a bit how the PTO works.

The PTO clutch disengages the 3pt hydraulic pump. Once the 3pt is disengaged, you pull the PTO lever and a collar connects the PTO shaft to the back of the 3pt hydraulic pump.

Since my 3pt disengages anytime I let off the pedal it must have a clutch for the 3pt. And since the clutch for the 3pt and PTO are the same... that means I have a PTO clutch. Since I have a PTO clutch and a 3pt pump, all that's left is the PTO shaft, associated spacers, seals, and retaining plate as well as the PTO control lever, plate, pin and seal.

I don't think it will be tremendously difficult, just need to have all the right parts. I did find something in my service manual that says "When no PTO shaft is installed, a pilot pin, is used with pin support, at rear of hydraulic pump. Tighten pin, to 50ft-lbs" It has a couple dark pictures showing the pilot pin.

So maybe I will have to access this pin and remove it prior to installing the other parts. Still trying to figure this all out, but it seems quite possible.