M59 hydraulics got slow and weak.

[Hersheyfarm]

I'm glad you said that. The technical stuff is fun, but it boils down to your needing your backhoe to move faster. That makes sense. Have you timed the cycle times on yours? That might answer all the questions. And for warranty issues timing it would be definite and repeatable. Somebody suggested doing that a while back. Sorry, but I forgot who it was. Anyway it sounded good so I took a stopwatch along with my M59 Kubota manual and timed the various loader and BH cycle times on ours. It was sort of surprising how closely it matched the published specs.

Normally I run at about 2/3 rated speed and less than that for light work. At full rated RPM it feels less efficient because of the boom speed. Of course the problem might be with me rather than the BH, but in my hands it sure slams and throws things around.

Regardless of the RPM, The M59 controls don't seem to allow the BH bucket to move in all directions at once. If it could do all motions simultaneously that would certainly speed up the BH work. Some industrial machines have that ability and I miss it.
rScotty

The full rpm/heat dissipation comment was explained that it is better for the cylinders to cycle with full power rather than being cycled at lower power where 'build up' psi is slower.

I can't believe we are discussing wether an industrial machine should be ran at rated rpm's.

 

[Hersheyfarm]

Also, Scotty there are certain circuits that override each other but they can be feathered for full animation of multiple cylinders. That's where the slowness comes in. Flow, flow, flow.

Good to know yours is close to the shop manuals cycle times. I will time mine as well.

 

[lhansman]

I have to agree with you Hersheyfarm. I have seen several posts on TBN from members talking about how gently they rev their engines and bragging about keeping their RPM's below 2,000 or some other value in the belief that they are "protecting" their engine. These Kubota diesels are designed to be run and run hard. When I am really working the backhoe I never operate at less than 2,500 RPM and it didn't hurt my B21, B26 nor do I think it will adversely affect the longevity of my L45. In fact I have noticed that when I operate the L45 with the Auto Throttle engaged that if I put my foot into it that Kubota will raise the engine RPM to over 2,500 and I can't believe they would do that if they thought it would hurt their engine. For the record, when I first start the L45 I disengage the Auto Throttle and use the manual throttle gently until the engine has reached operating temperature and then I turn on the Auto Throttle and put the L45 to work.

I have been following you troubles for some time and in fact based on your experience and that of a few other M59 owners I decided not to purchase one and instead bought the L45. I do hope you get your problems resolved soon as I use my machine commercially too and can only imagine the frustration you have been going through. I did encounter slow swing on the L45 once but it turned out one of the levers under the seat had moved and once it was pushed back in the problem was solved.

Wrt hydraulic oil temperature I have never measured mine but I know on the B21, B26 or the L45 after a couple of hours of steady backhoe or loader use there is no way that I could hold my hand on one of my cylinders. In fact when I have had to work on an open station on a cool day for long periods of time I have warmed my hands more than once by holding onto a cylinder to thaw my fingers out.

I hope your dealer gets your problem solved soon.

Regards,

Lauren

 

[Hersheyfarm]

I have to agree with you Hersheyfarm. I have seen several posts on TBN from members talking about how gently they rev their engines and bragging about keeping their RPM's below 2,000 or some other value in the belief that they are "protecting" their engine. These Kubota diesels are designed to be run and run hard. When I am really working the backhoe I never operate at less than 2,500 RPM and it didn't hurt my B21, B26 nor do I think it will adversely affect the longevity of my L45. In fact I have noticed that when I operate the L45 with the Auto Throttle engaged that if I put my foot into it that Kubota will raise the engine RPM to over 2,500 and I can't believe they would do that if they thought it would hurt their engine. For the record, when I first start the L45 I disengage the Auto Throttle and use the manual throttle gently until the engine has reached operating temperature and then I turn on the Auto Throttle and put the L45 to work.

I have been following you troubles for some time and in fact based on your experience and that of a few other M59 owners I decided not to purchase one and instead bought the L45. I do hope you get your problems resolved soon as I use my machine commercially too and can only imagine the frustration you have been going through. I did encounter slow swing on the L45 once but it turned out one of the levers under the seat had moved and once it was pushed back in the problem was solved.

Wrt hydraulic oil temperature I have never measured mine but I know on the B21, B26 or the L45 after a couple of hours of steady backhoe or loader use there is no way that I could hold my hand on one of my cylinders. In fact when I have had to work on an open station on a cool day for long periods of time I have warmed my hands more than once by holding onto a cylinder to thaw my fingers out.

I hope your dealer gets your problem solved soon.

Regards,

Lauren

Thanks for the input. And for the record I love this machine. And I would have no problem buying kubota again, they know how to build equipment. This is a unique machine in its size and power, and I think kubota got hit with some kinks on its debut.

To this day I will not use stall guard because i feel it had something to do with pump failure. Auto throttle.. I hope not because it is an awesome feature.

 

[lhansman]

I absolutely love the L45 and the HST+ features too. I have done a lot of loader work this summer - I hauled at least 100 six ton loads of fill from my place to my buddies up the road and I have found the Auto Down Shift and Stall Guard to be real time savers. I will let you know if I see any adverse effects as a result of Stall Guard but I am at 225 hours and so far no problems.

The M59 I looked at was an 08 with 550 hours on it and what really attracted me to it was it already had the Laurin cab on it. I could not arrive at a mutually agreeable price with the dealer that had it and my local dealer gave me a heck of a deal on an L45 that had been stuck at another dealers for some time so I went for the new L45 with a warranty instead.

Regards,

Lauren

 

[TBarD]

I too use Stall Guard and Auto Down Shift all the time for loader work (usually with the throttle up at 2300 or better for something as hard as loader work). Most loader work can be done in HI-M range with these settings, while digging hard into a pile or bank. The M59 with the 7' bucket is a beast for loader work. Recently I loaded seven or so 12-14 ton loads of wet gravel road base into a dump truck to spread on some new road, took about 2-3 hours for the whole operation.

The HST functions only affect the tractor HST drive, not the hydraulic pumps, although if one is also operating the loader the hydraulic pump will be loaded as well, with maximum load on the engine. If air entrainment is bad enough it can result in cavitation which will destroy a hydraulic pump in short order.

 

[indianaEPH]

where are you drawing the fluid from, the rear dip stick?
ill try the same with my m59 tomorrow

 

[Hersheyfarm]

where are you drawing the fluid from, the rear dip stick?
ill try the same with my m59 tomorrow

From the fill hole right beside the dipstick. I warm mine up for a few minutes and that's all it takes to se the bubbles.

 

[rScotty]

where are you drawing the fluid from, the rear dip stick?
ill try the same with my m59 tomorrow

That's how we've all been taking the samples, but there's a problem with that method. By all means do the test, but until we figure this out be cautious about what you see. It would be better not read too much into it just yet. I've been thinking about the science of our sampling method. So much "entrained air" just seemed completely wrong to me. What I pulled out of my sump simply is not consistent with how well my M59 hydraulics are working. Not just the M59 - I don't see how any hydraulic system could work with so much so-called "entrainment". Something's wrong here. So I've been thinking about what might have caused it. And I've come to the uncomfortable realization that there's a mistake and that I'm one of the ones that started it. All because I didn't look carefully enough at what I was seeing. Some of my initial assumptions were wrong. Could be that I'm the guilty party here.... :-( ...........ugh..........

Thanks to TbarD and then to Google for getting my mind working. It turns out to be well known fact that all hydraulic fluid normally contains about ten percent of dissolved air (by volume). That means that even the perfectly clear hydraulic oil in our photos actually contains quite a bit of air. The air is dissolved in solution and not visible. So the fluid looks perfectly clear.

And we know from physics class that any combination of reduced pressure and increased temperature will cause dissolved gases to form into bubbles. In fact, it turns out that I've done quite of a bit of this sort of experiment and somehow forgot just how a surprisingly little pressure difference will start fluids boiling. You can even boil the difficult ones - like ice water or infused epoxy - by using a cheap hand vacuum pump. Forming bubbles is not a gradual linear process; it is a step change. For example, we all know that at standard temperature and pressure water boils all of a sudden. Lower the temperature a few degrees and no bubbles. Lower the pressure a few PSI and boiling starts again. Think about pressure cookers....and about frothing gasoline as you fill your tank.

When we draw a sample from the rear dip stick hole on our tractors we do it by pulling the oil up with vacuum. That lowers the pressure on the fluid substantially. Add that lower pressure to a transmission oil that is a little bit warmer from being run and maybe a little bit entrained from normal pump action and simply drawing up a sample could be enough of a pressure change to cause the normal dissolved air to come out of solution in the form of bubbles....What I'm saying is that without a doubt some part of what we are calling "entrained air" is nothing more than an artifact of how we are collecting the samples. We just don't know how much we are causing. Might be near nothing and then again it could explain it all.

Bottom line: I believe we are making a mistake. The way we are collecting the oil sample is causing some part of the bubbles which we have been calling "entrained air". We need to be drawing the samples at normal operating conditions. And not by using a vacuum or syringe.
Enjoy!
rScotty

 

[indianaEPH]

Scotty:

I was just using my BH yesterday and was thinking how well it worked. I quickly dug a drainage trench and then ripped out a large stump in about 1/2 hour. So my though is that my system is working as it should. It will be interesting to see if I get the same results.

I understand your analysis of the sampling method. It could very well be the problem. I'll do the test and report the results. Also, I have a lighted bore-scope, of sorts, I may stick that down in the sump to see what I can see.

 

[Hersheyfarm]

That's how we've all been taking the samples, but there's a problem with that method. By all means do the test, but until we figure this out be cautious about what you see.
When we draw a sample from the rear dip stick hole on our tractors we do it by pulling the oil up with vacuum. That lowers the pressure on the fluid substantially. Add that lower pressure to a transmission oil that is a little bit warmer from being run and maybe a little bit entrained from normal pump action and simply drawing up a sample could be enough of a pressure change to cause the normal dissolved air to come out of solution in the form of bubbles....What I'm saying is that without a doubt some part of what we are calling "entrained air" is nothing more than an artifact of how we are collecting the samples. We just don't know how much we are causing. Might be near nothing and then again it could explain it all.

Bottom line: I believe we are making a mistake. The way we are collecting the oil sample is causing some part of the bubbles which we have been calling "entrained air". We need to be drawing the samples at normal operating conditions. And not by using a vacuum or syringe.
Enjoy!
rScotty

Well since I started this.. The first time I saw this oil in this condition is when draining it into a clear jug for filter change. If your so curious try that, or take your little syringe and slurp some warm fluid up from a bucket and see what you see. If your syringe tube is bellow the surface of the fluid and doesnt itself have a "suction" leak you are getting good results.

Most equipment that works this much fluid have a large tank for hydraulic fluid storage, not just the tranny. Think about all the fluid circulating in this thing. And untill I see samples from other types of equipment this fluid could be more normal than most think. Plus the suction part of the system is in itself a large vacuume, or syringe. same physics.

 

[indianaEPH]

OK, I also checked my fluid after use. I don't have pictures but it is the same as RScottys. Before use it is clear, after use it has lots of tiny bubbles. However, The loader, transmission and back hoe all work well.

I would say that this is not evidence of an issue with Hersey's Back hoe.

 

[Hersheyfarm]

OK, I also checked my fluid after use. I don't have pictures but it is the same as RScottys. Before use it is clear, after use it has lots of tiny bubbles. However, The loader, transmission and back hoe all work well.

I would say that this is not evidence of an issue with Hersey's Back hoe.

OR its an issue with all ours...kidding(kinda)

Thanks for checking, I feel better with three of the same samples. I have raised my fluid level just to see if it helps with bubbles but no. I am now starting to think the back boom is just kinda slow compared to a full size backhoe. I'll learn to live with it. I will check my tractors fluid out of couriosity.

 

[indianaEPH]

1 other bit of information. When I took the sample with the suringe I did it very slowly. So the suction, or negative pressure, would have been very low. So I think Scotty's suction induced buddle theory is out the window..

Also, this is my fisrt BH and it does what I need it to do. Hersey may be expecting and needing more. Maybe what is acceptible to me, in terms of the boom swing speed is not enough for someone that is use to more? BTW I measured my boom swing speed and it was a bit less than 3 seconds from 90deg to center. Have you done this Hersey?

 

[TBarD]

It appears that some amount of air entrainment is normal with hydraulic systems and with the M59 in particular (according to these tests we likely see this in all cases). In hydraulic systems this is a common issue. The main reservoir is designed with this in mind, e.g., it should be large enough to allow some time for air to bubble off (and for the oil to cool), anti-foam agents are added specifically to reduce foaming resulting from this process, the return line must be below the surface to avoid agitation, the suction line must be well separated from the return and sufficiently below the surface to avoid formation of a vortex which could suck in air. The suction section must be short and without bends, clogged filters, or other obstructions to minimize a drop in pressure which would increase bubble formation. Cold temperature and increased viscosity increases suction pressure drop which makes bubble formation and cavitation more likely during startup, which is why we have multi-viscosity fluids such as SUDT2.

The amount of dissolved air a hydraulic fluid can hold decreases with higher temperature, and the pressure drop in the suction line increases with the flow rate of the hydraulic pump, at constant temperature/viscosity. The amount of heat produced increases with engine RPM and with the system load as well as with the flow rate working against obstructions in the hydraulic circuit. Open center systems run at full flow rate regardless of load so all factors leading to increased air entrainment are enhanced as engine RPM increases. The diesel engine may be able to run at max RPM all day but this does not mean that the hydraulic system can do so as well, at least not without heat buildup and increased air entrainment as a result. If the M59 produces 16 GPM at 2700 RPM it should deliver e.g. 13.6 GPM at 2300 RPM, with consequent reduced system resistance and heat buildup, and increased cool down time in the circuit.

I don't think we can rule out an air leak or other issue with HersheyFarm's M59, but it is quite possible that the machine can be worked hard enough to overheat the hydraulic system. System load, ambient temperature, or oil viscosity and formulation could all be an issue. Perhaps we should be monitoring oil temperature and maybe engine EGT, and reducing load if necessary, if we are working these machines to their maximum.

 

[indianaEPH]

Tbar

I think that your analysis makes sense.....but Kubota is not a small equipment fabricator so I find it hard to believe that they would recommend 2700 rpm if the hydraulic system can't keep up with the thermal loading. But who knows. If the oil cooler is obstructed, or slightly obstructed this could certainly push the hydraulic system over the edge, so to speak.

My oil cooler got blocked with various chaff and I had to remove it to clean it out.

I never run my machine at 2700rpm but I'll try it this week end to see if I can determine any ill effects (I doubt it because it will be in the 60s this weekend).

Hersey: Have you inspected your oil cooler? Sorry if this has been covered but I don't want to read the 15 page thread again.

 

[Hersheyfarm]

Tbar

I think that your analysis makes sense.....but Kubota is not a small equipment fabricator so I find it hard to believe that they would recommend 2700 rpm if the hydraulic system can't keep up with the thermal loading. But who knows. If the oil cooler is obstructed, or slightly obstructed this could certainly push the hydraulic system over the edge, so to speak.

My oil cooler got blocked with various chaff and I had to remove it to clean it out.

I never run my machine at 2700rpm but I'll try it this week end to see if I can determine any ill effects (I doubt it because it will be in the 60s this weekend).

Hersey: Have you inspected your oil cooler? Sorry if this has been covered but I don't want to read the 15 page thread again.

Yea its been inspected by dealer, not me. this thing was in shop hooked up to their hydraulic tester and they only found a couple of bad check valves. They even looked at the screen in sump.
Anyways I am looking in my shop manual at it says swing cylinder from 90 degree to center is 2.1 second but they dont list rpm. what was your rpms when you timed.

 

[indianaEPH]

I tested at 2500 rpm. I think they would normally check it at max RPM.

 

[TBarD]

I think that your analysis makes sense.....but Kubota is not a small equipment fabricator so I find it hard to believe that they would recommend 2700 rpm if the hydraulic system can't keep up with the thermal loading. But who knows. If the oil cooler is obstructed, or slightly obstructed this could certainly push the hydraulic system over the edge, so to speak.

It should be able to run all day at 2700 without overheating - with no load. When working the machine hard though, overheating is definitely a possibility, with any hydraulic system. Overheating is also possible if there is any leakage in the hydraulic system, e.g. a faulty valve, seal, or just too much time at relief pressure. If overheating is suspected it is easy to check with an infrared temp gun. Normal operating temp should be between about 130 and 150 max. Anything over 180 is too hot and will harm components. If the oil cooler is suspect it is easy to check with the IR gun, just measure the temp at the outlet vs the inlet to see how much cooling is being delivered. If an overheating issue is suspected it might be wise to install an oil temperature gauge or alarm.

Also, in the case of "slow and weak" don't overlook the obvious! (the directional levers used to switch between backhoe and 3pt modes). This one caught several of us out already.

 

[Hersheyfarm]

Mine is right at spec for cycle time.

Kubota told me they are ok with 180 degrees on their hydraulics systems. I have no ideal why, nobody here agrees with that. One of the pumps is bolted to the block which gets pretty hot itself. How can they cool against that? Most pump are not bolted to the block and that makes since.