Grand L 5240 rotary broom?

[Fallon]

Specs say the main pump is 9.1 gpm. But I am unfamiliar with hydraulics at this level. If I suck out 7 gpm for a broom, does that leave enough flow to run the main tractor systems? Wouldn't make much sense to run the broom but be unable to drive the tractor, for instance. But this is my ignorance on this topic. And not even sure how I would tap into that.

The main hydraulic pump runs steering & external hydraulics (loader, 3pt, any extra hydraulic valves, etc.). Pretty much all modern machines have a priority valve that forces a percentage of that flow to run steering. So there is no using up that flow. The pump is designed to not have enough capacity to stall the tractor.

The first valves in the flow of hydraulic fluid can divert that fluid to do work, starving everything downstream. So if you move your loader, the 3pt stops working. But the 3pt will be fine & lift as soon as you stop messing with the loader. This is relevant to me as my hydraulic post hole digger on my loader stops spinning when I lift or drop my loader. Annoying, but not problematic. You would likely see similar behavior with the broom stalling every time you changed angle hydraulically. No big deal, just slow down & know it's going to happen.

If you have a HST machine, the HST has it's own dedicated pump & motor combo in the transmission that deals with moving the machine. A GST (most any power reversers or PowerShift type machines really) has a dedicated pump in the transmission to run the clutches & other parts that make a GST work automagically. A manual shift doesnt have or need any pumps in the trsnsmission.

 

[dstig1]

Interesting, but I have to say that doesn't sound like a great setup if it stops working like that on you. Do you have more info on how it is all connected - like maybe photos or a thread with your work setting it up? i am curious to learn more. The spec sheet for my tractor says it has a main pump 9.1 gpm, then a power steering pump at 4.7 gpm. It does not mention the HST pump, but there must be an additional one for that. Yes mine is HST.

 

[Fallon]

Interesting, but I have to say that doesn't sound like a great setup if it stops working like that on you. Do you have more info on how it is all connected - like maybe photos or a thread with your work setting it up? i am curious to learn more. The spec sheet for my tractor says it has a main pump 9.1 gpm, then a power steering pump at 4.7 gpm. It does not mention the HST pump, but there must be an additional one for that. Yes mine is HST.

Read up on "power beyond" & open center hydraulics. There is plenty of good info on TBN & elsewhere. Will make things a lot clearer. Interrupting my PHD sounds like a big deal, but really it's not. Especially given moving the loader isnt really an all or nothing action. If I feather the joystick, the PHD slows but doesnt stop as it's getting partial flow. I had the dealer put a 3rd function on when I got the machine. Its plumbed in the same as the 3 rear remotes I put on my old machine (http://www.tractorbynet.com/forums/hydraulics/295816-kubota-l3200-tnt-3rd-function.html) or 95% of the remotes or 3rd functions on any tractors. Again do some reading now that you have some key terms to start with (knowing where to start when you know nothing was half my fight before I knew better or ended up on my first hydraulic project).

The only easy way to get continuous flow to multiple work ports on any non industrial or large ag tractor would be with a PTO pump setup. Starting cost on building one of those is $2-3000, more if you buy one. I can deal with a fair bit of hiccups on my PHD when moving the loader for that price. It would let me get more power to the auger though. 10gpm * 2,500psi (standard max pressure for a tractor) is only 14hp or so. You can well over double that on the PTO of my machine. There other ways you could get flow to multiple ports like the flow dividers for steering, but they tend to not be reliably viable for tractors for various reasons.

A lot of tractors have a flow divider for steering, some have a pump with 2 chambers (1 for impliments, 1 for steering). Sometimes its documented oddly or wrong depending on where you get the info. The steering flow numbers are usually right, but may or may not be subtracted from total flow. 7gpm for impliments & 4 for steering sound reasonably normal though.

Dont plan on finding gpm specs for a HST. It's not a relevant spec in the real world. A HST transmission is conceptually a hydraulic pump connected to a hydraulic motor, but in practice its packaged up as 1 unit. Any relevant flow never leaves that 1 unit or is usable elsewhere. Its capable of transmitting more power than the engine can produce, unlike the hydraulic pump that runs impliments & steering. That pump is deliberately sized smaller than engine power as typically PTO or wheels do most of the work.

 

[TMGT]

You're tractor has a dual pump setup (2 pumps piggyback on 1 drive). You're total impliment flow is what the spec says so 9.1, typically rated at either pto speed or max engine speed if they're different.

The only models kubota makes now with single pump is the BX as far as I know.
All the Kubota's I've tested are accurate on the hydraulic flow numbers.

If you are going to use the 3rd function off the loader you might want to check that it is rated for constant flow, I know some 3rd function valves are only rated for itermitent use.

 

[redman135]

Around here the local roading companies almost all use a kubota with a pto (rear)mount pump with external oil reservoir powering a front mount broom.

 

[dstig1]

I have a third function that I added myself, but it is with a diverter, so it is not rated or able to do constant flow. I would use the third function for angling the broom, but need another solution for driving it. The PTO pump and tank like Redman suggested is what I am now leaning towards. But i really don't have time to start building this yet. i am curious still about the option to drive it off the tractor hydraulics, but I do not know enough yet on how or if that would work. I need to read Fallon's thread, for one. It isn't easy to find practical articles on how open center hydraulics and power beyond REALLY work. When it comes to the hardware and what goes where, I have not seen a good thorough explanation yet.

 

[dstig1]

Been doing some refresher reading on hydraulics. Some of that stuff never really made a ton of sense to me, but I think I am catching on. The theory makes sense to me, but putting it into practice is where I seem to get more confused. Like this:

So I have 2 rear remotes (Kubota factory, dealer installed...then reinstalled CORRECTLY by me) for the top-n-tilt. Kubota allows 3 valves max in their factory kit, so I could add one more. But my 2 re-center themselves to neutral/closed when you release the levers. If I could get the third one and have it stick in one position to stay open, then I could use the tractor hydraulics, potentially as that would provide the continuous flow required. Is this called a detent valve? And if so, does Kubota make one for the Grand L -40 series? If so, and the flow is sufficient, I could add that on and then run hoses to the front for the broom, with disconnects of course.

 

[aczlan]

Been doing some refresher reading on hydraulics. Some of that stuff never really made a ton of sense to me, but I think I am catching on. The theory makes sense to me, but putting it into practice is where I seem to get more confused. Like this:

So I have 2 rear remotes (Kubota factory, dealer installed...then reinstalled CORRECTLY by me) for the top-n-tilt. Kubota allows 3 valves max in their factory kit, so I could add one more. But my 2 re-center themselves to neutral/closed when you release the levers. If I could get the third one and have it stick in one position to stay open, then I could use the tractor hydraulics, potentially as that would provide the continuous flow required. Is this called a detent valve? And if so, does Kubota make one for the Grand L -40 series? If so, and the flow is sufficient, I could add that on and then run hoses to the front for the broom, with disconnects of course.

Yes, yes and yes.
You could also use something (say a small bungee cord or a T shaped piece of plastic or metal) to block open one of your existing remotes to have the same effect.

Aaron Z

 

[dstig1]

I wouldn't want to lose my TnT as i need it for my back blade for snow removal, and adding a third remote would not be a huge deal in the grand scheme. Also not keen on the bungee method, but it is a possibility...

 

[mikester]

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