Insane Hydraulics
Bold and audacious blog about fluid power
These pictures aren't notorious by themselves - just a couple of broken parts from a busted Sauer Danfoss series 90 closed loop unit, maybe the charge pump is damaged a little bit more than "usual". Clearly, something "extremely foreign" got sucked into the inlet... What I found interesting, was the fact that, whatever it was that'd cracked the charge pump, it also passed through and jammed open BOTH of the multi-function valves at the same time.
The story behind these pictures, however, is extreme in its "unbelievableness". Take the oil sample, which looks like it's at least 30000 hours old, with the amount of sediment in the bottom of this perfecly adequate sampling bottle suggesting ISO particle count in the neighborhood of 24/24/24.
If you take the trouble to check the oil-cleanliness compatibility chart, you will see that not only the oil isn't suitable for working with dirt tolerant gear or vane pumps, it is not suitable for working with hydraulic hoses and fittings!
Of course the machine broke down in the most inconvenient place, and, get this, the owner, despite all the reasoning, insisted on re-assembling the pump THE WAY IT WAS (with the split charge pump, jammed valves and all...) with the objective to move the machine for at least several meters from the place where it came to such an abrupt stop! "...mayhaps revving the motor up will do the trick!.."
My only regret was I couldn't be there to see it, because it would be like watching someone who said he could walk on water to actually try do so. Even knowing it's impossible, you'd still hope to witness a miracle...
And then there is a motor somewhere in the circuit... What? No need to check it? As I was saying, folks, don't we all feel good when wishing for a miracle?..