M59 hydraulics got slow and weak.

[mike69440]

It's an open center system. Very simple. When no work is being done, the flow is high and fluid simply races around the system from pump to sump and around again. Working pressure is developed when the operator moves a spool valve to divert some of the flow away from the main fluid path and over to a higher resistance path such as the line leading to a hydraulic cylinder.
rScotty

I guess that is refered to a parallel/series open circuit. Principles of Hydraulics

 

[Hersheyfarm]

My John Deere does not do this, Thats why I thought it was odd. There is no load other than the hydraulics themselves. Must be a Kubota thing.

David

All the 310's I've ran, my 580L, my Massey 4345... Usually dumping bucket will lug the motor a little.

 

[dsgsr]

All the 310's I've ran, my 580L, my Massey 4345... Usually dumping bucket will lug the motor a little.

This does not lug a little, it lugs the engine a lot, just lowering the loader while moving lugs it alot.


David

 

[TBarD]

My M59 has a bit of hydro whine/chatter for a minute or so when starting in cold weather, after which it is fine. I find that this is decreased when I engage the clutch. After the tests I ran I find that the machine when worked hard can warm up enough (after several hours) that one should monitor temperature and back off a bit if it is getting hot enough to endanger the hydraulic system components. However I have never seen any decrease in performance. I doubt if it would be practical to increase cooling significantly as the machine is just not that big, and the 12 gal of fluid is not that much for a 15-16 gpm machine. I suspect the air entrainment may be normal for open center systems (reservoir open to the air, ~10% air in solution), but have not been able to confirm. Bottom line - I am quite happy with the M59 and the compromises that went into its design.

 

[TBarD]

Correction, the total hydraulic pump capacity on the M59 is 26.7 gpm as Hersheyfarm noted; 16 gpm is just what the main hydraulic pump provides for backhoe/loader/aux (all at rated rpm). But we are running 26 gpm or so through a 12 gal reservoir. And yes it is open center.

 

[Hersheyfarm]

After I fed yesterday with my 4345 I drained some hydro fluid. It is very dark fluid because of the clutch I assume, but it was sparkly with air also. It was also still cool after running for a half hour. After it sat it was clear of sparkles. Maybe a hydraulic temp gauge is in my future. One more thing to stare at and obsess over.

 

[Hersheyfarm]

Been putting a lot of hours on this summer. The best way to describe my problem is sometimes the back boom feels 'heavy'. I changed the 3 hydro filters and there was a very fine black sludge on the magnets at top of filter. I would guess just metal residue from gears.

There was a very noticeable change in the response/speed of boom. It's just a little faster and a little more responsive for a wile.It's aggravating that its not consistent. I do watch the temp gauge of motor and at its hottest it never gets into the last 2 bars of the gauge, that's an hour or so of digging in mid 90 temps.

Sometimes I wonder if I'm just being **** on this, but there is a noticeable difference in the hydraulics.

 

[TBarD]

Been putting a lot of hours on this summer. The best way to describe my problem is sometimes the back boom feels 'heavy'. I changed the 3 hydro filters and there was a very fine black sludge on the magnets at top of filter. I would guess just metal residue from gears.

There was a very noticeable change in the response/speed of boom. It's just a little faster and a little more responsive for a wile.It's aggravating that its not consistent. I do watch the temp gauge of motor and at its hottest it never gets into the last 2 bars of the gauge, that's an hour or so of digging in mid 90 temps.
.

The temp gauge on the console is monitoring the engine coolant temperature (at least I have always assumed so). The temperature of the hydraulic system is essentially independent and must be monitored separately. I use an IR gun which is very convenient to use and can monitor any visible point in the system.

 

[rScotty]

The temp gauge on the console is monitoring the engine coolant temperature (at least I have always assumed so). The temperature of the hydraulic system is essentially independent and must be monitored separately. I use an IR gun which is very convenient to use and can monitor any visible point in the system.

Check me on this thought....It's sounding more and more like the M59's hydraulic cooling was originally designed a little too tightly....too close to max. There's not much reserve fluid...small sump, and so the fluid gets worked hard. The workshop manual advises a max temp at 140F on the fluid, but I think the measurements we've made show we're all pushing that. The system works for those of us in cooler climates running at 75% rpm, but TBarD's temp measurements show that the cooling is marginal. For Hershey's use in a hotter climate at full rpm the cooling of the hydraulic fluid might be the culprit. He's using the BH within specs, and by now there are enough posts so that we know he is seeing something the rest of us aren't. I admit it's a simple thought, but would explain a lot.

So can we make some simple changes to enhance the cooling? It might not take much. I don't see a downside.

Take a look at the hydraulic lines to the BH for example. I don't know how much cooling the original Kubota design engineer expected to realize from the surface of the hoses themselves, but it would be a substantial amount and easily calculated. Surely he did those calcs. But what happens when half or more of those hoses are covered with a heavy abrasive-resistant fabric? They are on my machine and given that the fabric is held on with zip ties it has the look of an add-on. Did the original designer anticipate that? That covering is nice for preventing damage (thanks, Kubota)..., but it has to interrupt the ability of the hose to rid itself of heat. In effect, those hoses are insulated. I wonder if it could be as simple as that?

Or take a look at the lines to the thumb. For half their length those thumb hoses are fabric covered, and for the other half of their length the same lines have a coil wire covering. I wonder if that makes a difference in how those hoses transfer heat to the air?

Of course we don't always use the thumb when running the BH, so chances are that system doesn't circulate enough that way to be the answer, but how about the main and boom cylinders themselves? There is lots of surface area there and anyone who has touched those cylinders while working knows that they get very hot. What about mounting some aluminum fins against the convenient part of those two big cylinders? Might be good to use some thermally conductive mastic there between fin and cylinder....., or maybe just a good fit would do it. The top surface of those big cylinders is very accessible, lots of heat transfer area, and some modest aluminum fins bedded in thermal conductive mastic and held on with some work clamps wouldn't be in the way of anything.

The heat gun would tell if it is effective.

Or how about the hoses themselves? Can something be wrapped around some of the BH hoses in such a way to help the hose surfaces themselves to transfer heat?

Maybe there are already some products like that on the market....Anyone know?
rScotty

 

[TBarD]

The M59 has a lot of power for a smaller/lighter machine; nice to have the power when you need it, but it does heat up if worked hard long enough.

I doubt if adding passive cooling would have a measurable effect, compared to just working the machine slightly less hard. In particular with the backhoe there should be much more heat loss from the big cylinders than from the hoses. When the machine heats up the whole bottom of the tractor (in the sump area) is the same temp as the oil, and this is a large surface area.

More active cooling could help, but would be hard to achieve. The best solution might just be to stop and have a beer every so often...