The implements do not move or they are erratic, you step on the brake pedal and the implements move again.
Post a Serial number please. Do you have access to Cat ET or a scanner.? You are most probably going to require one or the other.
Jms00876If I have access to the et I do not have service codes, implements have already been calibrated and even so it does not work at the pilot pressure intake it gives me 500 psi and it does not work when I press the brake pedal it gives me 2300 psi
If you hold the either LH or RH brake pedal pressed right down and keep it in that position does the implement system operate correctly.?
With the two separate pedals it does the same but only by keeping them pressed and it operates correctly
Were you aware that the same pump and hydraulic system supplies implement pilot pressure and braking system pressure for the service brakes.? The attachment may help. Have you checked the nitrogen precharge pressure in both accumulators.?
Does low nitrogen pressure affect the pilot pressure of the implements?
Thanks, I will check the pressure of the brake accumulators and let you know.
I have been thinking a bit more about your problem. You said........... Is this when measuring pilot pressure or implement hydraulic system pressure.? Because pilot pressure is only supposed to be 300psi. See the attachments. Please confirm at which location you are testing pressure and exactly what values and under what conditions those pressures are measured. NOTE: If you were measuring main relief pressure and could only reach 2300psi there is also something wrong because the setting is 3000 ± 50 psi for a standard machine such as yours. I would suggest to do the implement pilot pressure test first (if you have not already done it) and confirm the readings.
when measuring pilot pressure
You measured 2300psi on the pilot system...............!!! Are you sure you were measuring in the correct test point.? Please check the attachment I posted above for test points and the procedure for testing pilot pressure.
G7
That’s the main implement hydraulic system test point. Relief setting at that point should be 3000psi, so if you are only getting 2300psi as a maximum at that point something is not right. See the attachments I posted above, especially the one showing the test points. Do the test for the implement pilot system (you have to test at more than one point) and report your results.
g7 It is pilot pressure according to the diagram
If you are measuring anything between 500 and 2300psi at that point it CANNOT be the test point for pilot pressure despite what the schematic might say. It will not be the first time that a Caterpillar schematic has been mis-labelled. The specification for pilot pressure is only 310 ± 45 psi. Go back to Post #9 above and download the attachments, then do the procedure for checking pilot pressure. If your machine does not have a 3rd function it will involve testing at 4 different locations, one at each end of the lift and tilt valve spools.
Test point 22 is correct for pilot pressure supply test. If the pressure is that far above spec I would be checking the pilot pressure reducing valve on the left side to see if it's sticking.
One more thing to try is to raise the loader arms in the air, shut the engine off then turn the key on and try lowering the arms . This system uses loader arm back pressure through another pilot pressure reducing valve to give you a way to drop the loader if the engine is dead. If it passes this test I would definitely be checking the primary reducing valve.
The pressures are already fine, only the pilot pressure does not reach the main bank, only 13 psi
The reducing valves are new and the solenoid valves also I only have a linkage sensor code, does that affect it?
I did the test that you mentioned of raising the implement and with the engine off the ignition switch and the implement does not go down even a little.
We had 3 of the 980H's at a place I worked in. By 10,000 hours they all had to have the accumulators changed out as they would not supply the emergency braking with the engine off/key on and the machine moving in neutral. Had to change the pump ( multiple pumps stacked together) on one with about 8500 hours . It is a cab off job. You need to put positive air to the hydraulic tank ( 2-4 PSI ) on a modified filler cap every time you dump out all the oil, or the pump can starve on start up. They tend to not suck that hard, and it protects the pump on start up. Have also hooked up a quick connect on the left side of the machine just behind the cab on the test port for pilot pressure, on start up and let it spray through a skinny hose into a pail to bleed the pilot pump on start up to get the oil going instantly. Just need to do for 10 seconds, and main pump being forced oil from air in hydraulic tank at the same time. That is my experience working on these units. Simon C