Bad News. During the last max performance test late today on the X actuator, I blew the hell out of that aluminum valve between the s/v manifold and the actuator. Because of no accumulation on the system, I could only get about 80% of 1 cycle w/o running out of oil. I was running at 0.95 Hz at about +/-220 mm when the valve blew apart. It broke in two pieces and sailed across the lab. The one set of ports that did not fracture were bowed out about 1/16". AND, because the HSM shunts pressure to return AND there are NO hand valves in the hard line we lost about 60-70 gallons of oil due to siphoning from the pump before we got all the hoses off and capped. Good thing I was there cuz Robin had NO idea that the pressure hose was the BIG culprit. The drain lines were back-flowing too, but at pretty small flows. The pressure hose to the actuator, being shunted to return by the HSM, made it so the pump return was open to atmosphere at the actuator. The return hose has a check valve but counts for nothing because it is shunted by the pressure dump to return. AND, the return hose has to come off TOO because the check valve has that DAMN orifice in it. I am NOT perfect in what I do, but this time I was being VERY careful because the high accelerations were making some really big banging noises and that was worrying me. I was almost there, when BAM....game over.

At the time of the accident, the acceleration was about 7 g's. When the actuator runs out of oil, the servovalve closes at a bad time and you get horrendous accelerations. This is not uncommon in seismic. It can easily happen on an E-Stop during any high velocity motion. The 7g accel turns into about 8000+ psi in the actuator port which is obviously too much for that aluminum valve. I am bringing back the 2 pieces with me. You can see the dent in the valve end that is towards the table cuz it hit the table going like a bat out of hell. FYI, I have OFTEN seen 9000 to 10,000 psi spikes on seismic tables. That's why the deltaP snubber will save the transducer. The psi comes from figuring out how many psi results in so many g's.....the accelerometer does not lie; therefore, it does reflect psi....

BTW, what is that valve for? IT seems to be a flow reducer of some kind. Is that for when the specimen is that overweight case? Then it makes sense to limit velocity cuz of the cushions....UNFORTUNATELY, it is in a REALLY bad place for over-pressure. Maybe there is a better way to do it somewhere else in the flow path that is not so rife with high pressure.

Obviously, we did NOT complete acceptance. Robin was planning to stay until Wednesday next week to work on the 793 w/ the customer some more. He has graciously offered to help clean up the rest of the oil tomorrow (got about 10 gallons in the pit yet and the table is sopping wet). He WILL be able to run the 793 next week cuz we got everything capped off at the HSM. Robin did real yeoman work to dive in there and get it done. A couple Suviet guys did as well. Otherwise, we might have lost all the pump oil. It was gushing out......