Hitachi EX120-2 Main Pump?

[mg2361]

Don't forget to check the Pilot Pressure Reducing Valve pressure also. That pressure is critical to the operation of the compensator valves.

 

[DFBluffton]

@Jason Klassen and @mg2361, @LACHAU ??

Yes all tests where in P mode.

I am not sure where the pilot pressure reducing valve location is to test. Any diagrams?

So these tests don’t lend to a main pump needing a rebuild? I thought pump pressure was to be at 4200psi?

 

[mg2361]

In the Hitachi manual, it would be listed as the Pilot Secondary Pressure (section 6, group 4). You do have the Technical manual, correct?

Low pump pressure does not necessarily mean a bad pump. That machine has too many variables that could cause poor performance. The only way to be sure about the pump is to perform a pump flow test.

 

[DFBluffton]

@mg2361 - Thanks. I see in the tech manual you need a fitting and T, I only have hydraulic gauges and the fitting, so will need to find a T.

How may I do a pump flow test?

 

[DFBluffton]

Also, that pilot second pressure t’s back into the 4th line on that block.

That’s different than from the tech manual.

 

[mg2361]

How may I do a pump flow test?

That takes special equipment that cost $$$$. You would need someone who already has that tooling and the knowledge of how to flow test that pump on that system.

Check your PM's.

 

[Jason Klassen]

What do you have running off that last spool? That one on the end on the left side is the auxiliary. On mine I have a thumb and the line for the compensator just returns to the top of the spools where the pilot lines are and then to the tank. So my compensator for the thumb is never used.

Yours looks like its teed into the bucket compensator so that the bucket and the thumb (if that's what you have) receive the same compensation.

@mg2361, would this setup be beneficial compared to mine?

 

[mg2361]

would this setup be beneficial compared to mine?

Off the top of my head, I don't know. I would have to study this.

 

[DFBluffton]

@mg2361 , ok secondary pilot test done.

0 psi on below port. Unless I did something wrong. Full throttle, same bucket push against tracks, nothing.

picture below of port I tested with gauge.

what’s that mean?

 

[Jason Klassen]

Looks to me like you may have been trying to measure PC Pressure and not pilot secondary pressure. I have attached some pics from the manual. Its a little confusing because in 4.2 Pilot Secondary Pressure the darkened line in the first pictures is the one you were testing (goes to a compensator) and the second picture shows the gauge connected to a pilot line at the top of the main control valve.

 

[mg2361]

Actually the Pilot Secondary pressure can be checked at the solenoid manifold.

Check your PM.