I found a furnace oil burner pump, that may work for larger model's, they can be had cheap on e bay.
http://http://www.ebay.com/sch/i.htm...ntec+a2va-7116
The trade off is, they are on the large side of thing's.
Here's a spec sheet for some of the model's, I have the Suntec A2VA-7116
It is 2-3 gallons per hour, vs the German pumps that are about 4.72 gallons per hour or 300 milliliter per minute if my math work's?
http://http://www.suntecpumps.com/Suntecus/A7000.htm
This pump is rated at 3450 rpm and 2-3 gph at 150-200psi. The shaft is 5/16
with a flat spot for set screw. They have 2 tank lines, 1 for oil supply, and the second one is a return line, I believe they have a built in relief valve.
Now before some of you get excited about it's tooo big for 1:14 Tamiya truck's, yes I will agree! But for big dozer's, excavators, and other large equipment. Picture #2 is next to a Tamiya Flackpanzer Geppard tank transmission. The motor pictured, is a stock Tamiya 540 can. I'm planning on using my pump in a future dozer project, no screw drives now!
This is the link, for the entire Suntec manual, with spec's. It is a very large file, beware!
http://www.suntecpumps.com/Suntecus/...e%20Manual.pdf 81 pages! They also make a 1750 rpm model.
Yes this will stir the pot a little bit, its the best cheap option, that I have found in 2 year's of looking! It ain't easy to find a happy balance.
Hope this helps a few of us out? No it won't fit in a Bruder skid steer loader!
Cheer's, Neil.