So whatcha figure Henry, the best bang for Jeff's $ would be to build a pump that caters to the 2% scale you build in or the 80% that build in 14th.
Kidding aside
, it's not that you need high pressure, just higher flow. The majority of pmd's stock in the past has been 1.5mm hose & fittings between the valve(s) & cylinders.
With my newer Stahl Komatsu loader & Liebherr excavator, both these models have 2.5mm plumbing throughout the hyd system & I'd say it's near triple the speed of cyl cycles.
In your case of 10th scale, I'm sure a 350ml pump will easily handle 3mm plumbing, maybe even 4mm, but that could be stretching it's capabilities with pressure fluctuation.
The kind of pressure you seem to think you need to have would be like my 850 hoe, and this hyd system is freaking huge & expensive! Did you look at Ole's & Kalle's build threads on Scale4x4 that I linked to when I 1st show my 850 build? Approx area for pump, brushless motor, reservior, up to 4 valves = 9x4x4 inches. Will that fit in your Terex or Caterpillar? That's a Jung pump & I'm only guessing here, approx flow 500ml/min @25 bar recommended.
http://i172.photobucket.com/albums/w...0/DSC07142.jpg
Hmmm, I never dove that far into taking the Leimbach pump completely apart. I saw the bronze bushing behind the drive gear... just assumed the seal relied totally on tight tolerances. Learn something new everyday. Thanx for the insight Rob & Jeff.
Though I wonder about the comment of the steel gears chewing up the aluminum body... if the tight tolerance is lost between the top & bottom of the gears, then the oil would no longer flow only around the outside of the gears to make pressure. Right?
I've never had a pump loose pressure. It's my belief that the oil darkens mainly b/c of the aluminum cylinder barrels... once we get our hands on stainless steel barreled cyls, the proof will be in the pudding.