I recently purchased some old gear pumps and transaxles. In doing my research and from what I have learned from Daniel these hydrogears were used on the JD 140 tractor. Digging further, it is only the first 2-3 years of 140's (1968-69 and maybe 70 serial # 0-30,000) that they used this set up. From what I can gather, new parts for these units are no longer available. I talked to a gentleman tonight who said they did not even offer a gasket kit anymore. Also, looking at pictures of Don Lehmann's Roof Palomino, some version of this set up was used on them as well. I am sure there were others.
One of my tractors is fairly weak, and I am most likely going to swap it out with another one I have on the shelf. Before I do I want to test it to see how much pressure it is producing. I went to two local shops for a 0-1000 pressure gage and neither had one and both said go see the other guy, they are too expensive to stock. Looking on ebay, looks like there are plenty of them cheap.....am I missing something. Here is a link to the ebay page......any of these do?? http://www.ebay.com/...=p2047675.m2392
Also, do I jack up the tractor, so I can activate the rear end to see what type of pressure is being produced. Sorry, first time I have done this and looking for some guidance.