On Thu, 12 Jun 2014 11:00:51 -0500, "Pete C."
wrote:
wrote:
I have a mid 70s Case CK780 backhoe. The thing had seen lots of abuse
before I bought it and I have used it pretty hard since. The power of
the hydraulics has gotten weaker over the years. I used to be able to
kill the engine by trying to push or pull too hard. Now this doesn't
happen. So I'm thinking that the pump has a lot of wear. Over 30 years
ago I used to repair gear pumps in a lumbermill I worked in by
grinding the end plates of the pumps to remove scoring. But I don't
know how much more pressure the pumps put out after this repair, it
was just what I was told to do and I did it a lot. Considering the age
of the tractor I'm wondering if I might just be better off buying a
new pump and also if there is somwhere else I should look for the
lowered power of the hydraulics. The power loss has been gradual over
the years so I'm thinking it's probably the pump.
Thanks,
Eric
Is it open or closed center hydraulics? Better machines will be closed
center and they will have variable displacement pumps, not basic gear
pumps. Step one is figure out what type of system you have, step two is
install a pressure gauge in the system and see what pressure you are
operating at. In an open center system you will only have pressure when
you operate an axis to it's limit, on a closed center system you will
have pressure all the time. An open center system will have a relief
valve that limits the max pressure and they can certainly develop weak
springs, debris causing leakage, etc. On a closed center system the
pressure setting is controlled in the pumps displacement control which
causes it to go out of stroke when the pressure limit is reached.
Factory manuals are a good thing to have, particularly on the more
complicated closed center systems.
FYI
http://www.coincollectorkings.com/tag/780ck
http://www.ebookily.org/pdf/allis-ch...anual-download
http://us.aolsearch.com/search?s_pt=...vice%20manuals
--
Unka' George
"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"
-Norm Franz, "Money and Wealth in the New Millenium"