hi I'm looking for some help on my dozer51px which brought a Hyd oil light on as a fault and stopped travel, the dozer was in a very isolated area so the operater removed filters and tried too flush them clean the replaced,the dozer worked for a few hundred yards untill it broke down again, a electrician from Komatsu went and said it wasn't electrical but the PMT cartridge was only showin 11bar and should be 30 has anyone had this problem any info would be great thanks
I have no knowledge of this particular machine, but if it is hydrostatic then it sounds to me like you have had a catastrophic failure of a pump or motor, or both. If there was metal in the filters, that would be conclusive evidence. Low charge pressure usually means serious internal leakage somewhere.
thanks Ian that sums up what Komatsu were sayin today, something keeps throwing me of that its the main pump etc, seemingly if the cooling fan is turning the dozer won't work if the cooling fan is stopped the The dozer will work it's seems to be a mystery ha
Well, if the cooling fan is hydraulic and the fan motor runs off the charge pump, Bob's your uncle you may have a cooling fan motor failure? Or it's just that the charge pump is not keeping up with internal leakage somewhere AND the fan motor?
that could be the answer Ian thanks, would any of the relief valves sticking or failing cause this too happen aswell or am a just needing to accept that its the pump lol thanks for ur info Ian it's appreciated
Possible, wish I had a hyd schematic for that machine. Just about any component that can bypass or dump oil out of the loop will cause the unit to stop working for one reason or another. If the charge pressure is too low for instance the servo pistons that stroke the pump can't push hard enough to override the centering springs, that's just one possible problem.
If the machine became disabled and was able to be recovered under its own power it is not likely a major failure as then there would have been no recovery. Maybe as simple as the transducer being contaminated, wiring fault, cylinder failure plugging filters, etc. Did the electrician connect a mechanical gauge or just went off of the computer?
Hi mike the dozer has no Hyd the electrician used the computer too check the charge pressure which was roughly 10bar, am going to the machine tomorrow to put gauges on it an to see how I get on thanks for all the info an tips
release pressure off the hyd tank, remove case drain hose from left motor and cap the hose but leave the motor open, start unit and if oil pours out at a high rate of speed you may have an issue, do that on left and right side. Could also cap off the ma and mb ports ( 2 high pressure lines) on the left and right final drive motors separately and together to see which side if faulty and test the hst pump at the same time, will also want to check final drive oil, seen quite a few suck the final oil in to the tank past the shaft seal.
Hi komatsu told us that the shaft seal could be the problem, wee fitted a new charge pump and tried too move the dozer, the dozer started too move untill the cooling fan kicked in full blast and brought a warning light on, it only seems to stop travel when the cooling fan kicks in, did u have this problem too or could it be a sticky spool that's stealing the charge pressure cheers
you need to start by checking to see if the final drives have oil in them. Check case drain on left and right final drives and may as well check the fan but I very highly doubt that a fan motor is causing this.
as DK88 said you need to check final drives. My buddys 39 and my burnt up pumps at around 1200 hrs for this reason. It pulls all the nasty metal shavings and oil out of the final drives into the pumps. This is before it makes the loop and gets to the filters. I was told it was filtered first before it went into the pump. I found out differently after they replace the pump the first time. Around 50 hrs after the first replacement i got stuck, the final drive got full of sand from a seal failure, pump locked up 200 yards away after getting unstuck. It was full of sand, as was everything esle on the dozer except the filters.