In an attempt to get the best performance out of my 190, I read in the service manual that a pressure test will tell me the condition of my system.
A pressure test is an important indicator of the health of the hydraulic pump. Case made a "Hydra-Sleuth" available to its dealers that not only checked pressure but it also checked oil temp and oil flow.
So I installed a gauge (0-3000psi) between the pump and the PTO valve body, right where I can see it, on the left fender.
I am assuming that you located the hose that leaves the hydraulic pump and goes directly to the IN port on the fender-mounted PTO/FCV. And then you installed a Tee fitting on that IN port to accept the gauge.
Some questions I know will be ask about my situation:
Recommended pressure per the book: 1250-1500 psi
You do not state which book you are referencing. Presumably, you are relying on the copy of the 150/190 Service Manual you have. As you know, we don't have that here..........yet. :lol: This book
http://www.manuals.casecoltingersoll.co ... marked.pdf
has a chart on Page 5 that shows the Relief Valve Specifications. The relief in the Travel Valve is supposed to begin opening at 1500 PSI plus or minus 50 PSI but it will go wide open at 1600 PSI plus or minus 50 PSI. In other words, if you did not have the optional PTO/FCV valve on your tractor, you should see 1600 to 1650 PSI on the gauge with the throttle wide open, the rear wheels NOT spinning and the Travel Valve pushed fully forward to deliver max oil flow to the wheel motor. The fact that you have the optional PTO should change that pressure reading to 1700/1750 PSI because the system would now rely on the relief that is built into that PTO to protect the pump from damage. It is customary for the FIRST relief in an open centre hydraulic system to have the highest setting. The reliefs that follow after, will be set slightly lower. As Gator stated in his reply, relief springs do lose tension over time due to always being under compression in a hot environment.
Perhaps your Service Manual/Hydraulic section shows the PTO/FCV valve. If so, that would be very helpful. If not, then that is a problem. :lol: The easiest way to explain it is to send you to this manual
http://www.manuals.casecoltingersoll.co ... marked.pdf and have you examine pages 36 and 37. The ITEM numbers 4 through 10 make up the relief valve in the Travel Valve. In this instance, two springs are used. I have no idea if the PTO/FCV used one or two springs in its relief. However, you can see that a SHIM WASHER is used (Item 6) to put additional pressure on the two springs just as Gator mentioned. Gator would have been working on much larger valves in order to use coin of the realm as shim stock. :lol: Here's the dilemma you face. It MAY be that your problem is with weak springs in the relief and replacing those springs would solve it or shimming those springs would solve it. Then again, it MAY be that your pump is just worn out and is not capable of developing enough pressure to force the relief in the PTO to open up. That's where the test using the grease gun comes in because a hand operated grease gun will give you absolute control over the amount of pressure going into the PTO valve as the gauge is being observed. The pump cannot be damaged by over pressuring it because the pump is not connected while this test is performed.
No wants to throw money in the wrong direction if it can be avoided. However, you are the current owner of a 46 year old tractor that is showing a very low pressure reading. Logic tells me that there is a much greater probability of your pump being worn out than there is for the relief springs to lose that much pressure due to sacking. If you have more time than money available, then you could CAREFULLY take the relief in the PTO apart, making sure that you drop nothing and also note the ORDER in which things leave the body. If you have a local hydraulic repair shop that knows their stuff, they will have shims of different thicknesses available. You could add one or two shims and then test the system again to see if a higher reading is noted. If so, then keep adding shims until the ideal pressure is reached. The alternative is to just spend $250.00 and buy a brand new pump. Stick it in, run the test again and see what the results are. My guess is that will solve your problem but I could be wrong.
Oil stats: 20-50, changed and screen cleaned about 50 run hours ago
Intended use of the tractor: tilling, dump trailer towing, front blade dirt work.
For the test, I warmed up the tractor by using it as I normally would. Let the engine idle for a minute or two, throttle up to 1/3 and go find something to till up. As I worked, both tilling and pushing with the blade, I watched the gauge. This is what I saw.
Tilling, avg 800, peak 1000 with audible releif valve actuation (squealing)
Dozer work, low range, avg 700 peak 1075 - Peak pressure read as tractor comes to a stop against plowed up dirt, pressure does not increase after tractor stops.
This is the test that tells the story. Your highest reading was 1075 PSI when it should be up around 1700 PSI. None of the other tests you did are asking for the pump to work as hard as it possibly can.
Flat ground travel, low range, avg 550 peak 800
Flat ground travel, high range, avg 700 peak 950
The test was done with both cold and warm oil temp, but numbers were not different enough to post. The numbers above were recorded with warm oil and full throttle setting.
Given the numbers, I think my next step should be to adjust the travel releif valve to around 1300 or so, this should give my tractor greater ability to tow the loaded dump trailer and to push dirt.
Here's where I need some help. I'm not all that familiar with the hydraulic drive systems of these tractors, but I KNOW that many on this site are well versed in this. I don't expect to find a fix-all answer here, I know this could get complicated.
My tractor has PTO valve, Flow Control Valve, and attached tiller.
Could any of these components be responsible for the loss of pressure? Should I check for a worn or cracked travel valve?
Any help here would be appreciated, so thanks ahead of time!