Hydraulics

[dhuskey]

RTV 1100 Kobota; In cold weather, I loose my power steering and hydraulics. The tractor has the origional fluid in it. It acts like it is air locked.
After it sets two or three days, I start it up and I have not power steering and my bed dump has no hydraulics.

 

[Hooked_on_HP]

If you are in a location where it gets below freezing I would guess you have moisture in your hyd. system that is freezing and you need to change your fluid and filter to remove the moisture.
Bill

 

[J_J]

Seems like a pressure gage would solve this frozen pump mystery.

 

[RickB]

Seems like a pressure gage would solve this frozen pump mystery.

If hydraulic functions are lost, it's a safe bet the system pressure is at or near zero. The question is, why? Fluid quantity, quality or viscosity, filter quality and condition, suction tube leak, etc.

 

[J_J]

If hydraulic functions are lost, it's a safe bet the system pressure is at or near zero. The question is, why? Fluid quantity, quality or viscosity, filter quality and condition, suction tube leak, etc.

I understand zero pressure, with the engine not running, but if that engine is running, and the shaft on the pump is good , then it will be trying to pump fluid with no or very little pressure if there is nothing downstream to impede the flow.

So, if engine running, pump good, and fluid is in the pump, then fluid is being pumped.

Even if the relief valve is frozen, the fluid running through it would soon melt the ice, so a pressure gage is very useful. Every tractor should have a hyd gage anyway.

 

[AKKAMAAN]

Yes, J_J is right, get a gauge, or two, you will need it!!

If you have an open center system, oil is, most likely, bypassing, if pump is turning.....did relief valve,RV, seize in open position??
Make sure that pump is pushing oil around.... either with a 0-300psi gauge, or better visiually, by disconnecting the return line from directional valve or just squezze return line it a little with your hands, that will tell if there is flow.
Then go for the RV, tap it lightly on outside with a light hammer, if that does not help, try to adjust RV setting up and down....if that doesnt help, unscrew the whole RV unit and check it out, basically it should be a spring and a poppet inside....better read the Owners Manual first!
Allways use a 0-5000psi gauge to reset the RV pressure setting.
Post a symbol drawing over the system, that will help trouble shooting!!

 

[DaveOmak]

Seems like a pressure gage would solve this frozen pump mystery.

J J , You've given me great advice in the past. I'm looking to learn again.
Could a vane pump have trouble starting in the cold weather? Would a vane pump be used in that situation? Dave

 

[AKKAMAAN]

Some vane pumps can drain back to tank if they are mounted above the fluid level in the tank. The reason for that is that the vanes do not "seal" when pump is not running, or running on very low rpm's. (A vane motor have small springs pushing out the vanes) In most vane pumps, vanes need the centrifugal force from rotating, to make pump build pressure. I think I have have seen vane pump suction lines with a check valve (need to be almost zero cracking pressure) to prevent draining back to tank when not running.
I could imagine vane pumps could have problems with self priming if oil is thick from cold, and the vanes might also be little stuck or "frozen" in the rotor "slots".

 

[J_J]

I would agree with what AKKERMAAN said, plus you might take a look at the characteristics of the fluid in the tractor, and consider the lowest temp you might expect, and find a fluid that covers the complete range of your situation. If the machine has the correct fluid for the area, then I don't think you would see the problems that some have had. The no pressure when cold, is indicative of fluid that is degraded. A magnetic heater on the sump would help some. If the hyd fluid has ice crystals in it, I would consider that fluid degraded.

 

[Wayne County Hose]

RTV 1100 Kobota; In cold weather, I loose my power steering and hydraulics. The tractor has the origional fluid in it. It acts like it is air locked.
After it sets two or three days, I start it up and I have not power steering and my bed dump has no hydraulics.

Funny thing here is, that with no flow or pressure, all the best gauges in the world won't tell you squat.

 

[Egon]

Whats the fluid level at?

Is the system breather vent froze off?

Can you determine if the pump is turning?

I'm betting that a normal 5000 psi gage has graduations that are too large to be able to determine what the pressure is if none of the end attachments do not work?

 

[RickB]

Funny thing here is, that with no flow or pressure, all the best gauges in the world won't tell you squat.

That was pretty much my point, thanks for agreeing.

 

[Willl]

Vacuum gauge on the inlet side ?

 

[J_J]

Well, guess what folks, the absence of pressure with a gage installed, and engine running, is indicative of a pump not function correctly, and therefore a reliable test function. No pressure, well, maybe something wrong, you think, but maybe not, with no valves in operation, there might not be any pressure showing on the gage. and fluid flowing right past the gage. So, would a gage help diagnose the situation, yep, I think so.

 

[AKKAMAAN]

Make sure that pump is pushing oil around....

If you find out that there is a flow, look for the reason for no or low pressure. If pump is moving oil, there must be a bypass some where, including internal leakage in the pump. If there is no flow, than troubleshoot the inlet side, suction line, strainer, tank vent etc, plus the power connection to the pump shaft...

 

[RickB]

Well, guess what folks, the absence of pressure with a gage installed, and engine running, is indicative of a pump not function correctly, and therefore a reliable test function. No pressure, well, maybe something wrong, you think, but maybe not, with no valves in operation, there might not be any pressure showing on the gage. and fluid flowing right past the gage. So, would a gage help diagnose the situation, yep, I think so.

In this instance, we know the system isn't exibiting any evidence of pressure and flow without benefit of a gauge in the system. However we don't know the reason for the lack of system performance. With a gauge on the system, there still isn't evidence of pressure, however there is no identified cause for the system's lack of performance. A gauge serves absolutely no purpose in identifying the cause of the symptoms.
Gauges are useful in evaluating systems that are at least partially functional. In the case of an inoperative system, they are useless because the readings are totally predictable. I can't imagine why that is so difficult a concept for you to get your head around. Except, of course, you simply don't agree.

 

[J_J]

Whatever point you are trying to make, it isn't working. I do believe the OP said he lost some of his hydraulics, and therefore a gage in the right place would help determine the reason for the loss of fluid. Loss of power steering , doesn't mean the whole system is down. Whoever came up with the ice theory is just a guess, but I can see, where fluid, emulsified with water, might freeze, and I really don't know what would happen. If that tractor has that much water in the fluid, then it should be replaced.

Enough about the gage thing, it is a useful tool if you know how to use it. You all can keep on with this if you want to, but it is futile. I sure do apologize for saying things that you don't agree with.

 

[waldron]

I own an ag-king 3540, a hydraulic hose blow off the in flow line to the pump. I replaced it. hydraulic does not work now. i was moving snow here in asheville,nc. I replace a gallon of gear oil 80-90 by mistake, some say thats okay, others say no okay. I drain the it, and replaced it with hydraulic fluild. still does not work, will not lift front bucket or reaf lifts. some say I have air in the line. Is there a way to release the air. did not change the hydraulic filter. got any suggestions?

 

[AKKAMAAN]

I own an ag-king 3540, a hydraulic hose blow off the in flow line to the pump. I replaced it.

You mean the suction hose?? Blow or collapsed??

some say I have air in the line. Is there a way to release the air. did not change the hydraulic filter. got any suggestions?

If pump get oil normally from tank, air on the pressure side is NOT a problem. Air will get pushed out.

 

[EE_Bota]

Questions about a Kubota will likely do better in the Kubota forum, since most issues about hydraulics come down to information about the specific machine, rather than general hydraulics.

I personally have rarely seen a hydraulic pump that failed and can produce NO FLOW, rather, usually the pump can produce some flow.

The best way to make a rotating pump appear to have NO FLOW is to do silly things such as:
have the fluid so low that the pump cannot pick it up, or have the fluid be so viscous that it cannot go up into the pump.

What is rather obvious about a pump is:
They can produce various pressures, up to the many thousands of PSI, but none of these pumps can SUCK oil out of a sump harder that a FULL VACCUUM. Most cannot approach a full vacuum, however.

Therefore, I would suspect a clogged suction filter, a broken suction line, or oil emulsified with water to the point that it would simulate a suction filter clog.

A guage is handy in this case because pumps only produce FLOW and PRESSURE is created by resistance to flow, so JJ is right to suggest a guage because he is assuming, I believe rightly, that you can create resistance to flow by throwing a valve. If you then get pressure, but pressure too minor to move the load, your pump is likely ruined, or a relief valve is stuck. If however, you get no pressure in any case, your pump inlet path is screwed up, etc.