I'm frequenting this forum too often, lol. We have a PC300 that stopped all hydraulic movements. They switched the pump from another 300 and the outcome was the same. What could cause all of the movements to stop? Power is going to the safety solenoid and LS-EPS solenoids.
Good day Suggest start with the pilot pressure, look for JohnC he seems to know Komatsu products. Kind regards Uffex
X2
Thank you. I will look for him.
Full model and serial number are needed. There are many variations in those machines over the years.
My question is, when you say all hydraulics no movement , swing and crawlers as well?l
Yes, no swing nor crawlers as well.
That machine is either a 2007 or 08 model. Do you know if it is OLSS or CLSS system. If you don't know please take a photo of the pump which I can identify.
It is the CLSS system.
Does this have a pilot pump installed on the back of the main pumps? More than likely it has the pilot pressure reducing valve on the bulkhead side of the main control valve. Do you have any gauges to check pilot pressure?
It doesn't have a pilot pump installed. Pressure is coming out from it and going to the control valve to the small valve body that has the front and rear oil pressure sensors installed on it. But when we checked, there's no pressure coming out from that valve body. What exactly is that small valve body on the control valve?
Possible pump drive failure?
That body is a pilot pressure regulator. With a closed circuit system there is always a little bit of pressure on the oil leaving the pump. A lot of people call it standby pressure. In this case it is actually load sensing pressure. The CLSS system is designed to keep the flow output of the pumps so there is at least 300 PSI more than what any function needs. The LS pressure is used to supply the pilot system. That valve on the back of the main control valve is what does that. Komatsu as far as I know always puts places to install a manual gauge into the out put of the pump. If you find that you have at least 300 PSI coming at that point then it would indicate the pilot pressure reducing valve could be the problem. Was the drive coupler pulled off the back of the flywheel when the pump was changed? They look like a clutch without any facings.
The mechanic at that time didn't had a gauge to check it but when he unscrewed the pressure testing valve, there wasn't any oil coming out of that pressure regulator. No, they did not pulled that off when they switched the pump. The functions started working again when they changed that pressure regulator. Was that really the issue or would the same problem arise?
Your last post is confusing. Are you saying they didn't pull the drive coupler out when they changed the pump? Are you saying that the pressure regulator was changed and then thing started working again?
I apologise for the confusion. They first changed the pump with another one but the issue was still the same. Yesterday they changed the regulator and everything started to work once again. So it seem as though the previous pump wasn't the issue. So can the pressure regulator actually cause nothing to work?
The machine uses a low pressure system to control the big valves that send oil to the implements, swing and travel. We call it pilot pressure. It also controls the output of the pumps. If there is no pilot pressure, nothing is going to work. Sounds like someone owes you some money back on a pump.
Where does this pilot pressure comes from? It would appears so from what you're saying that they owe us money back on the pump. Are there many more possible causes for no swing, travel and movement of implements? Honestly don't ever want to go through that process again.
The fact that changing the pilot pressure control solved the problem is proof that changing the pump was unnecessary. The problem could have been electrical but again, when the pilot pressure valve was replaced the problem was solved. Good Luck!
Thank you so much for your guidance on the matter.