This is the identical situation I encountered last year. Oildyne people were wonderful to work with and told me about the hole in the spool valve orientation. However, when they sent me the schematic, it showed the spool pointing the other direction. I reinstalled mine based on the schematic and it has functioned correctly since then. There are a number of postings in the archives with actual pictures of the parts from the disassembled units which agree with the schematic and not the verbal instructions from Oildyne.
Garry,
<<I just talked to folks at Oildyne about the pump. By the way they were very helpful and friendly,... pleasant experience. They informed me, that in fact my spool was installed correctly. It appears that there is a hole on the face of the spool on the "O" ring side, which needs to face toward DN side, thus "O" ring side needs to face in my case toward DN side. This was determined based on my power-pack's Serial Number printed on the label by OILDYNE Co.
So I am back to square one, since I obviously will continue to have my GEAR-UP problem, when I will put it back together the way it was. Any suggestion would be very appreciated.>>
Don't give up yet, there is more to the story.
When this problem first surfaced several years ago, we determined that the build instructions for the pump were in error. I would not trust a reference by serial number because of this. Instead use the functional schematic from the Oildyne website applied to our application. To add to the confusion, note that the labels in the schematic for up and down need to be reversed. The more typical application does work during extension of the cylinder. Our application reverses the high and low pressure sides because our work stroke is during cylinder retraction.
The fool proof way to determine if the valve is in backwards is to put a pressure gauge on the down circuit, even if temporarily. If the valve is in backwards, you will read several hundred psi during a retraction sequence - enough to make the down circuit think the gear is already in the down position.
TRV=Thermal Relief Valve
HPRV=High Pressure Relief Valve
LPRV=Low Pressure Relief Valve
Hydraulic test stand - in this photo - found a leaking, 'new' high pressure dump valve from Lancair (red handle)
Highly recommend - Permanently installed hydraulic pressure gauges
Chris Zavatson
N91CZ
360 std