Komatsu PC228USLC-3

[Pocho86]

Hi

I have this Komatsu PC228USLC-3 Serial 20001 - up, It has no pilot pressure or hydraulics. It was working one day, next day they came back and nothing.

I checked the safety switch in the left hand console, had power in and out as it should
all the fuses and relays seems ok
power to the controller and everything seems to be OK electrically.

Some one prior even changed the Pilot Lock Out Solenoid on the Solenoid Bank. I manually powered the solenoid and that did nothing but click. I replaced the PC-EPC solenoid (There is a LS-EPC Valve Too) on the pump cause of what one guy had recommended and nothing.

The pump 1 and pump 2 does have the 500psi standby pressure when engine idling per the manual which is good so Im assuming my pump is good.

I have no pilot pressure, no pressure at the solenoid valve manifold were the 6 solenoids are at. That comes from the pump labeled PEPC on the schematic. I have no idea what exactly controls the pressure from within the pump to this circuit. There is a few things on the pump I have no idea what they are.

We removed the LS and PC valves on the pump and inspected them but nothing out of the obvious, all orings were intact.

Im at a loss if any one can make sense of this....

 

[John C.]

There are two types of pumps that you could have. The older ones have the pilot pump mounted on the back of the main pump. The regulator valve is on the piping coming off the pump. There is also a gauge connection port in that piping.
The newer setup does not have a pilot pump. They use a diverter valve type setup that is mounted on the inlet to the main control valve.
You first need to confirm that you have pilot flow to make the pilot system work at all. You need to install a gauge somewhere to confirm what is going on. Do you have a service manual?

 

[Pocho86]

708-2L-00102
PUMP ASS'Y

 

[John C.]

The pilot pump if you system has one would be attached to the back of the main pump. The drawing only shows the front of the main pump.

 

[Pocho86]

Looking at the schematic I have and parts break downs this unit doesn't have a separate pilot pump.

It either looks like it gets pilot pressure from the main control valve from a valve block thats bolted up to it called a Distributor and Confluence Valve cause thats were the pilot pressure checking port is at and theres also a valve in there called a pressure reducing valve which in the manual says its a pressure reducing valve to provides lower operating pressure to the PPC and Pilot valve system.

But theres also a line that comes from the pump

 

[Pocho86]

This is the schematic for this unit. Top Left is the Solenoid Valves, the large rectangle is the hydraulic pump, the three circles is the Distributor Valve thats mounted to the main control valve also showing pilot pressure checking port and the pressure reducing valve. Im hoping you can zoom in and following the lines. If not maybe DM me an email and I can send it to you so you can look at it closer.