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Hydraulic in cold

Posted by bckskin2 5 Il (My Page) on
Sat, Jan 17, 09 at 9:43

We are have record breaking cold in Il. the Hydralic on my tractor quit. Any tips to warm it up & keep it from happening again? It lives in a barn with my horses. It's in the grage with block heater on the hydraulics.
Any suggestion.


Follow-Up Postings:

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RE: Hydraulic in cold

how about a block heater on hyd tank if if is accessible?


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RE: Hydraulic in cold

forgot something, my cousin has a JD farm tractor with a FEL on it, one cold day it wouldnt work, found it had a bit of water in it that froze, in the hyd sys.


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RE: Hydraulic in cold

Yes sir.....cold weather and hydraulic systems are not good friends. Place a heat lamp or a small electric heater (radiant heater is preferred of this genre) near the hydraulic reservoir at least 4 hours before you plan to use the machine. A propane fueled catalytic heater is good also. If you have one of the high output (35,000 to 55,000 BTU) forced air heaters (either kerosene or propane fueled) you can do a quick pre-warming of the hydraulic tank (and the engine too, depending on your options for aiming the heater output). We used a kero fueled Reddy Heat heater to warm up an old Ford 4500 backhoe prior to trying to start it on frigid mornings. Our main goal was to warm the 3 cylinder Perkins diesel so it would come to life. We used a 90 degree, 8" HVAC ductwork elbow (which we secured to a concrete building block) to redirect the output of the heater upward instead of horizontally. We situated the concrete block & elbow so the elbow was directly under the engine oil pan. We placed the heater so that the outlet of the heater was about 18" to 24" away from the concrete block/elbow and fired up the heater. The heated air would flow into the elbow which redirected the heated air upward around the oil pan, engine crankcase, intake manifold and finally up under the hood where it would warm the radiator and the main hydraulic tank. About 1/2 hour was needed to wake the beast up. In lieu of "pre-heating" the hydraulic system you can use an "extended warm up" period to get the hydraulics "limbered up". Start the engine as you usually do (but extreme low temps might erase the word "usually" from the picture) and let the engine run at a fast idle or a bit higher for 3 to 5 minutes. This will warm up the hydraulic oil that is being recirculated in the "closed loop" from the reservoir to the pump to the control valve(s) and back to the tank. You can allow this time to be longer than 5 minutes if you like. After this initial phase of warm up is done, you need to perform the next step before taking off and beginning to perform actual work with the hydraulic cylinders (or in some cases, hydraulic motors). Beginning with the control circuit for one of the hydraulic "functions" of the machine, operate the control lever "veeerrry slowwwwly" so that the cylinder (or motor) reacts and moves slowly. If it is a cylinder, allow it to extend to the full length if possible (your building structure might impose limits if you are inside). Then reverse the direction to full retraction of the cylinder. Repeat this about 10 or more times. Do this same thing with all the functions (other cylinders) until you have displaced all the cold oil that was harbored in the hoses and cylinders, back into and through the tank and pump. If the function uses a hydraulic motor, feed the oil to the motor very slowly and gradually increase the speed over a period of about a minute. If the motor is reversible, do the reverse direction in the same gradual fashion. It is advisable that you operate your hydraulics a bit slower in extreme cold weather because the oil simply will not ever warm up like it would in warm weather. Also, while you are using your machine, you might be operating one or two functions "constantly" while other functions are not being used as much. Keep in mind that the oil in the unused circuits will cool down to the point they were before the machine was started up. Try to remember to operate those circuits slowly when you get to the point of using them. The greatest risks of damage to hydraulic systems in extreme cold are the possibility of "cavitation" occuring in the pump, and of having a hydraulic hose break from being rigid from the cold. Cavitation in the pump is what happens when the pump is "starved for oil". Normally, the "pumping surfaces" of the pump assembly are kept out of "metal to metal" contact by the film of oil in a properly operating hydraulic system where the pump is adequately provided with oil on the suction side of pump (inlet to pump). When "oil starvation" occurs (whether from a clogged suction filter, a kinked hose, or too viscous oil in cold weather) the moving surfaces of the pump will not have enough oil to keep them out of "metal to metal" contact. When these surfaces mesh or move during cavitation, metal will be worn off and in extreme cases, galling can occur. Wear will reduce the efficiency of the pump over time. Galling will result in rapid and complete failure of the pump. Galling is especially harmful because it sheds actual particles and flakes of steel which are then transported throughout the entire hydraulic system where they can forever cause scoring of control valve spools, hydraulic cylinder walls and pistons. If debris from pump galling is run through a hydraulic motor, the motor will be scored and damaged. It is crucial that the flow of oil through the pump not be reduced for any reason. If you are going to operate in extreme cold conditions, I recommend changing any hydraulic filters and oil twice as often as you would if you never operate in extreme cold conditions. The flow rate of a filter drops as trash is captured under normal conditions. Any debris caught by the filter reduces the flow somewhat. When the oil is very viscous due to extreme cold, the flow rate through the filter (old or new) is even less. Old oil that contains unknown quantities of water molecules is another source of concern. This water gets into the system in a few different ways. Most of it gets in through the hydraulic tank atmospheric vent or "breather" in the form of water vapor. Some water will enter the system when cylinders having a coating of water or frost are retracted. The wiper seal in the "packing gland" will squeegee most of it off but some will still get in. Any water that gets into a hydraulic system will ultimately "settle out" and fall to the lowest available place in the system, but before that happens, there can be an "emulsion" of water and oil flowing throughout the system. The older the oil, the worse will be the emulsion content (because the additives that guard against this are already used up from doing what they are put in there to do). In extreme cold conditions, some of water component of this emusion can freeze and when these ice crystals get to the filter, they can momentarily clog the filter. If this is a suction filter, it can cause the filter to collapse and will cause instant cavitation in the pump. If this is a return line filter, it can cause the filter to rupture or at least to unseat the bypass valve in the filter (either will allow some of the trapped trash to be released back into the oil returning to the tank). I thank you all for being patient with me in this typically (for me) long winded statement.


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RE: Hydraulic in cold

I've got a block heater on the tank, now one on the filter & a small electric space heater under it. Unfortunatly we keep her in a barn & hate to use any combustion in there. If I can keep it going til Spring I will do a full fluid change. I may change the filter tomorrow.
Thanks,
Jerry


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