Can the machine operate correctly (meaning electrically for the variable pump displacement) if the machine no longer has the electronic throttle controls? Our machine has a manual throttle that was installed by previous owner and the step motor and throttle angle sensor are gone but all other things are installed and plugged in
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Hitachi ex120-2 intermittent slow hydraulics for all functions.
- Thread starter Newberryi
- Start date
Diesel Dave
Senior Member
The bypass procedure only limits the maximum pump flow , it has no affect on the minimum.
You could try cycle timing the travel with the engine at full throttle, Work mode in M1 and in rabbit travel speed to get an indication if the hydraulic pump is capable of reaching close to maximum output.
From a running start over 65 feet of flat ground the travel time should be approx 13-14 seconds in rabbit.
Diesel Dave
Senior Member
Yes the machine can operate correctly with a manual throttle in relation to hydraulic pump control. The EC and PVC controllers only look at the speed sensor located in the drive end of the hydraulic pump housing to determine if the engine is being overloaded and excessively pulling down.
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I will check that but I believe we are able to get max pump flow. The reason why I think that is before we replaced the pressure switch the engine sounded like it was constantly under load when sitting still using no functions and when you would use a function it would bog the engine extremely bad and would black smoke. Could it do that and still not be at max flow?
Diesel Dave
Senior Member
I agree, it sounds like the pump is close to max flow.
BUT the question I have is how come you are unable to adjust the angle sensor even remotely close to the 4.4V spec with pump at max flow during the adjustment procedure.
If the angle sensor input to the PVC is truly only 2.0 V at max flow then the PVC has no clue what the pump shaft angle actually is.
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Diesel Dave
Senior Member
Diesel Dave
Senior Member
My manual the pages are not the same as yours.
See full procedure below. In step 6 ,the 2 connectors that are unplugged are identical so be sure to mark them so they don’t get mixed up when going back together.
See full procedure below. In step 6 ,the 2 connectors that are unplugged are identical so be sure to mark them so they don’t get mixed up when going back together.
Diesel Dave
Senior Member
My page #’s are different than yours but the angle sensor procedure should be in the last few pages of the “ELECTRICAL SYSTEM / Inspection and maintenance “
Ok we’ve been back on the machine today and correctly adjusted the angle sensor. Machine still has a slow intermittent hydraulic issue. We have not had the machine long and we have been trying to figure out this running issue before did the standard maintenance stuff like new fluid and filters so other than knowing that there was hydraulic fluid in the machine we knew nothing. Since we still had an intermittent slow hydraulic issue after adjusting the angle sensor and the weather was nice we decided to drain the fluid and replace filters. When we took the lid off the tank to remove the big long filter it wasn’t in there and that valve and spring thing that sits between filter and lid were gone! Could that missing filter and valve and spring cause the issue we are having!?? Can anybody explain to me what the function of the valve does??
Diesel Dave
Senior Member
No , the missing filter, valve and spring would not create intermittent slow hydraulics.
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The valve on top of the hydraulic filter is the filter releif valve .
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I would suggest to check the EC and the PVC ground wires for good solid connections with the cab/ floor. If I remember most of the ground wires are all bolted in the area of the seat pedestal mount on the cab floor. I had a Deere 490E had some intermittent hydraulic performance issues and ultimately that’s what I found was the issue.
Diesel Dave
Senior Member
When you are doing the maintenance,Be sure to check the hydraulic pump suction screen is still in its proper place in the bottom of the hydraulic tank at the outlet flange.
With that filter not being in the system like it was the fluid didn’t get to be filtered and I believe that was what was causing the fluid to be so aerated. We thought the fluid just looked like it had some water in it but when you look at sight glass with a flash light shining across it you can see it’s full of tiny bubbles. So much so that we thought the fluid was milky but it was just that aerated. Wouldn’t that cause pump and all sensors to be erratic because those bubbles can compress under pressure? If so then I could see the computer and sensors chasing around trying to satisfy pressure and flow. I can’t think of why else the fluid could get aerated so bad. Keep posting advice it’s helping us tremendously with getting this thing going. It ran much better today after angle sensor was set correctly. Ram flawlessly until the fluid got aerated
Diesel Dave
Senior Member
The aerated hydraulic oil although not an ideal situation , I do not think it would be the cause of intermittent slow hydraulics.
Since you discovered the hydraulic return filter was missing completely,maybe sooner than later check the condition of the hydraulic pump suction screen in the bottom of the hydraulic tank.
Also , after operating you should be able to feel or hear a slight air pressure being released when removing the hydraulic tank filler cap ? The air pressure in the tank helps to force the hydraulic oil to the hydraulic pump.
Since you discovered the hydraulic return filter was missing completely,maybe sooner than later check the condition of the hydraulic pump suction screen in the bottom of the hydraulic tank.
Also , after operating you should be able to feel or hear a slight air pressure being released when removing the hydraulic tank filler cap ? The air pressure in the tank helps to force the hydraulic oil to the hydraulic pump.
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Did you guys figure out the hydraulic issues? I have a ex120-2 and have sorted out a few issues. It now the hydraulics are getting hot 160°-170° after running 1hour. Lots of power and functions are fast. If I run in E mode it runs around 140°-150°. Curious what you figured out and any advice is welcome. Thanks