BX25 Mid PTO Pump or BUST

[Iplayfarmer]

Dare I say Artisan is develping a belly mount post hole digger?

 

[SPYDERLK]

So matching the torque output of the engine to the torque (resistance) of the pump is very critical to the success of the system?

Yeah sorta. ... It will be sucessful period, but since we are pushing so close to [and marginally beyond] the limit of HP available, a little planning is important to put us on the hi side of the limper loper continuum.

... When you combine the need for pressure and flow capabilities required to assure operation of a wide selection of implements at their full rated torque and output speed it takes to the peak, and beyond, of what the BX25 can deliver. The ploy of lowering pressure to enable driving a larger pump will give full hydraulic implement speed - but speed that cannot be backed up by torque when needed. The implement motor will stop dead as soon as the system pressure set limit is exceeded. Its not like an engine which has a lot of energy stored in inertia. An engine system will supply the peak overtorque, and if brief youll hardly notice. If sustained, a significant overload [say 2x] will lug the engine to stall in a couple seconds. - time to react. Now we could use the large pump and set the pressure relief high enuf to lug the engine to stall. This would be almost as good as a straight engine hookup, but the quick acting of a hyd relief will always decouple quick torque peaks that caused above PR surges, but that the engine would have ridden right thru. When you are operating near the pressure peak of the system you get nuisance stalls with hydraulics. Preserving the option of cranking up the pressure temporarily makes it a lot more convenient.
...Ill look a bit at the graphs and say more when I reply to Artisan.
larry

 

[Skyco]

Dare I say Artisan is develping a belly mount post hole digger?

I'm guessing the mother of all roto rooters:laughing:


It was asked about ratios of PTO's-

According to my BX24 Workshop Manual, I believe the BX25 is the same--

Mid PTO=2500RPM at engine RPM of 3043 so ratio = .8215577 which equates to engine turns 1.2172 times for every one spin of the mid PTO shaft

and for reference

Rear PTO= 540RPM at engine RPM of 3142 so ratio = .1718651 which equates to engine turns 5.8185185 times for every spin of the rear PTO shaft


I find it interesting they geared them for rated PTO output RPM at different engine RPMs. Might be nothing to that other than it was easier to do it that way with the gears they had available.

I long ago made a P-Touch label for my dash to remind me exactly what engine RPM made 540 at the rear PTO.

 

[J_J]

The gearing on the mid PTO was designed for the MMM, to get the high rpm on the blade spindles, which is a finish cut.

 

[Skyco]

Understood. Just wonder why they didn't set them both up where rated RPM of both PTOs was at the same engine RPM.
That way those of us with CRS don't have to remember two set points for engine RPM.

PS I really wish the BX series had a big ole analog tach, with set points labeled, rather than the miniscule digital tach.
For some reason they gave us a huge fuel gauge instead...

 

[SPYDERLK]

Well......other than a deep hole in the ground... what's ya all think about a
prince # SP20B16***** Not for log splitting, a system a guy can plug "stuff" into and do a lil work. The BX25 only has I think 3GPM's or so at the
curl, looks like almost 10GPM's from this if I can pull it off. (I drew a tank,
it is sweet! Well...we will find out when I post a pic for the pros to criique' anywho)

I found a Hydraulic T-Post driver that pulls 5.3GPM that might be perfect
for such a system, I "think" .

D902-ET02 is what the sticker on my engine says...FWIW

There are 2 performance curve graphs, one to 3600 RPM and one to 3200RPM.

I do not quite understand why unless there are 2 versions of the same engine.
I believe mine goes to 3200 RPM. I would suggest the 3200RPM graph is correct...

Nope, didn't miss that at all. His mid PTO HP in this case is a duty rating, but not the max limit of available power. A MMM will far exceed the 17HP rating a small percentage of the time. So when designing a system driven by the PTO it is acceptable to use max engine HP. Even more so when talking about implements that will be used while the tractor is stationary. I thought I had mentioned that a few posts back, but now that I look I see that I forgot that paragraph.:ashamed:

I'm guessing the mother of all roto rooters:laughing:

It was asked about ratios of PTO's-

According to my BX24 Workshop Manual, I believe the BX25 is the same--

Mid PTO=2500RPM at engine RPM of 3043 so ratio = .8215577 which equates to engine turns 1.2172 times for every one spin of the mid PTO shaft

and for reference

Rear PTO= 540RPM at engine RPM of 3142 so ratio = .1718651 which equates to engine turns 5.8185185 times for every spin of the rear PTO shaft

Cool - Info is IN! ... Now the question is, What is the nature of implement you see for use. Does this include many that want continuous full flow and rated pressure at the same time? Like a blower, rototiller, [or to lesser extent a mower because you can vary ground speed,] for instance. ... Or do you see major use on ones where nominal implement speed is not much concern, but resistance to motion can vary greatly. Such as sickle bar cutting brush, a post auger, rotary broom, etc.
-- The next question is, What else is the tractor doing?? Are these mobile or creeper, or stationary point of use applications? Go with too large a pump the tractor wont walk and chew gum.

... Looking at the table and 3200 engine graph it looks like the SP20B16 is a very good choice considering "Net Intermitent HP". You will be close to being able to sustain 3000PSI at 10+ GPM. [3200x.8216 = 2630pump speed.] You have essentially the same eng HP down to 2800 rpm where the pump will be turning slower and using less power. So you will be able to move around a little even with an implement working hard enuf that it wants 3000PSI. Not too touchy. Going down a pump size would ensure that it not be touchy at all, but may not be acceptable for speed sensitive implements. Going up a size would handle flow for sensitive speed implements, but the balance would go against the engine if they also needed hi pressure. You could leave the pressure relief high for implements encountering brief high resistance. The engine and tool would then power thru while eng rpm plummeted. Moving while working hard would be very touchy keeping the eng from lugging below its happy work range.
...larry

 

[J_J]

Artisan,

I have these specs on my B9200 HST. Do you have similar specs on your tractor?

Power Take-off (PTO):
Rear PTO: live
Rear RPMs: 540/748
Mid RPMs: 1847/2557

 

[Artisan]

Dare I say Artisan is develping a belly mount post hole digger?

HA! That would be a trick ehh? Perhaps a belly mounted hydraulic powerplant might better describe it, after that, run what ya brung!

 

[Artisan]

Artisan,

I have these specs on my B9200 HST. Do you have similar specs on your tractor?

Power Take-off (PTO):
Rear PTO: live
Rear RPMs: 540/748
Mid RPMs: 1847/2557

J_J I don't quite understand your specs, alls I find for a BX25 is this;

 

[Artisan]

Cool - Info is IN! ... Now the question is, What is the nature of implement you see for use. Does this include many that want continuous full flow and rated pressure at the same time? Like a blower, rototiller, [or to lesser extent a mower because you can vary ground speed,] for instance. ... Or do you see major use on ones where nominal implement speed is not much concern, but resistance to motion can vary greatly. Such as sickle bar cutting brush, a post auger, rotary broom, etc.
-- The next question is, What else is the tractor doing?? Are these mobile or creeper, or stationary point of use applications? Go with too large a pump the tractor wont walk and chew gum.

... Looking at the table and 3200 engine graph it looks like the SP20B16 is a very good choice considering "Net Intermitent HP". You will be close to being able to sustain 3000PSI at 10+ GPM. [3200x.8216 = 2630pump speed.] You have essentially the same eng HP down to 2800 rpm where the pump will be turning slower and using less power. So you will be able to move around a little even with an implement working hard enuf that it wants 3000PSI. Not too touchy. Going down a pump size would ensure that it not be touchy at all, but may not be acceptable for speed sensitive implements. Going up a size would handle flow for sensitive speed implements, but the balance would go against the engine if they also needed hi pressure. You could leave the pressure relief high for implements encountering brief high resistance. The engine and tool would then power thru while eng rpm plummeted. Moving while working hard would be very touchy keeping the eng from lugging below its happy work range.
...larry

Larry you da' man! WOW, knowledgeable is an understatement...

In a perfect world I would want "A" pump that will do it all, obviously
that is not going to happen. The pump I picked might be somewhat OK
but looks like a guy that wants it all would want to keep 3 pumps on hand
if a guy had all those varied demand implements in stock, switching
pumps with each different implement, tractor usage change. Certainly an
expensive way to go but, indeed necessary depending on implement used
and what demands you will put on the tractor itself robbing power from
the PTO.

If I have not said it before I will say I think the thing to do is build a
system as robust as possible w/ the given HP and RPM's, see what she'll
do and then look for tools that will run off what I built.

Tools I could use ...

Chainsaw 8GPM
Post Driver (interesting "Oil Dividers" they sell)
Auger
A powerplant for my Weatherhead hydraulic hose maker!

I am sure if I get a tank hung and a universal pump bracket I can figure out other things to do w/ it.