Solar 420LC-V S/N 1322 5281 hrs When we started to investigate the concerns with this excavator, all functions would cause a shudder, fairly rapid staccato type shudder, felt thru the floorboards and seat, more than anywhere else. The lower line (1 or 1 ¼”) that comes off the Rexroth pump also jumps around a fair bit. Have not done any flow meter testing yet, but with a pressure gauge into the ports for the sensors that report to the monitor, under normal mode, wide open throttle, and deadheaded, results : Front pump 4,800 psi Rear pump 4,400 psi The needle does not spike or jump at all Also teed a gauge right at the spool for the boom lift . It likewise did not spike or jump around . Pilot pressure is within spec. Found about ten particles in pilot filter, so dismantled relief valve in the same block as EPPR. It was difficult to shuttle. So I cleaned it, which made the bucket function smooth out. The accumulator was also found to be depleted so swapped a know good one from a 225 (same external size) Safety lowering etc works normally now with key on, engine off. Now we noticed the tracking also works normally, IE it does not create a shudder like it had originally. There seems to be plenty of power being developed, just the shudder (feels like cavitation) Question: Could the plastic coupler be nearing the end of its useful life, and how to narrow that down without removal of the pump? There is plastic dust debris on the rubber bell housing plug. Where do I go from here? Thanks so much ! "Places to go...... Things to do...... People to see..." Joel Martin Service Technician 515-745-2822 RTL Equipment P. O. Box 307 2601 120th St. Swisher, Iowa 52338 -Never underestimate the power of stupid people in large groups-
If you want a helping hand, you will find it at the end of your arm. That is why I normally persist until I answer my own question. I ended up checking hydraulic pressure out of the same ports for the sensors that report to the monitor, but this time at idle. Voila' - the rear pump made the needle flap like laundry on a clothesline in gale force winds. The front pump held a steady reading, moving of course according to demand. The pump is being gone thru at Sunsource. Hope this confession helps somebody out there. Of course it stands to reason that a broken spring or something might cause a shudder but at high RPM the gauge will not pick it up, eh?
I think that you will find that one pump group has dropped a piston. Not good news.
Sunsource in Savage, Minneapolis, rebuilt the pump, using the case, but replacing pretty much every other item. Installed today, runs like a top.