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Terex 842ss Hydraulic issues

greerco

Well-Known Member
Joined
Mar 15, 2014
Messages
45
Location
Spencerville
Hi im working on a Terex SS 842. Problem is the main hydraulic pump (a variable displacement piston pump with no load sense line( Rexroth a10v dr ) wont go back to idol pressure when no controls are being used. Firstly i had the pump checked and re built. Then checked all the removable cartridges in the system and found a pile of broken back up rings and o rings in the valve bodies. I replaced all the damaged which made a difference to the controls but not the pressure problem. Then i disconnected and plugged all lines from the pilot control valve to see if it would help. And again nothing. I did the same to the steering orbital valve and the brake valve and main spool bank. Still pressure is at 2000 psi. I also replaced the sense valve on top of the pump. Still no drop in pressure. The is an electric solenoid they call a pump discharge helper it was not working. After i fixed that it made a difference in the load on the engine, I am assuming only because it more direct return back to tank, but still no drop in psi.

I have had no help from Terex as far as a service manual is concerned. They say because its a painted white machine its a odd machine because it was in the years of when Terex and Genie were amalgamating. I contacted Genie, they told me check the online manuals, when i did the systems are not even close to the same.

I think i need to take all the valve bodies off the machine and take them completely apart on the bench and see whats going on. But hopefully not.

Any help would be appreciated
 
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