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.