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Subject: Hydraulic Lift,,,again !

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Charles(N.C.)    Posted 05-11-2017 at 13:19:18 [URL] [DELETE]        [Reply] [No Email]  
  • Hydraulic Lift,,,again !
  • Sometime back (I've been under the weather)I posted about my lift and what I was doing.I've pulled the top cover for repairs and removed the bottom pump.The pump had a stuck intake valve and the pressure relief was exchanged.The top I honed the lift cylinder smooth and replaced the lift pin.Used a new type cylinder piston and gasket.New hyd.fluid now NO LIFT !The fluid is moving in the pump with no aggitation and I see,feel no lift cylinder leaks.Now if I lift the arms by hand they will hold and when I cut the engine off the arms still hold ((how long ?)but the arms,pump will not lift.For the life of me I can only surmise the pump is not pumping fluid to the hydraulics.I'm still on some "under the weather meds" and one has just kicked in so I'm hoping I make scence.Help !Thanks!

    JMOR    Posted 05-11-2017 at 19:21:52 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • One more question. Having been inside there, you know that the 'dog bone'/connecting rod has no hard connection to the piston, so if after you are lifting the arms manually, it holds in the up position, then some fluid was pumped into the cylinder. So the only other way the arms would stay up is friction in the rockshaft bushings. If this were the case, lowering the touch control lever would not cause the arms to lower. Finally, the question: does moving the touch control lever to lower actually cause the arms to drop?

    Charles (N.C.)    Posted 05-11-2017 at 21:14:03 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • Yep,,,it will lower the arms.Even when sitting awhile the arms will lower.I do not know the workings of the control rod from the touch control but,,,in the lift position of the touch control the control rod pushes the exhust valve into the pump.Thats how it works.Why(???)don't have a clue.Somehow my thoughts are telling me the pump isn't pushing the fluid up into the ram cylinder with enough pressure.Geiger makes minchine of this pressure.

    JMOR    Posted 05-11-2017 at 23:38:53 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • No, that is not the way it is supposed to work. Lift command will push the control arm forward and push the Intake valve into the pump casting, resulting in opening the intake valve, as shown in picture.

    R Geiger    Posted 05-11-2017 at 22:33:42 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • With the lift arms chained down the pump should produce at least 1500 psi at the est port.
    If you do not have the FO-4 service manual, now would be a real good time to get one.
    It has a real good section on the hydraulic system.

    JMOR    Posted 05-11-2017 at 14:28:09 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • Remove right side round inspection port and visually or by feel (below oil level), make sire control valve(s) spool(s) are actually moving when you move the touch control lever. The (s) is because I don't see where you said 8N or 9N/2N.

    Charles(NC)    Posted 05-11-2017 at 16:20:09 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • The touch control is adjusted so as to touch (643) the housing as it reaches the top thus closing the intake spool valve(698).This is a early 8N.As said,,oil is moving,,none leaking at the lift cylinder,,but will hold lift arms up if I lift them (oil pressure? for a time.As has been stated ,,,,no pressure at the pump? Thanks

    Charles(NC)    Posted 05-11-2017 at 16:19:23 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • The touch control is adjusted so as to touch (643) the housing as it reaches the top thus closing the intake spool valve(698).This is a early 8N.As said,,oil is moving,,none leaking at the lift cylinder,,but will hold lift arms up if I lift them (oil pressure? for a time.As has been stated ,,,,no pressure at the pump? Thanks

    JMOR    Posted 05-11-2017 at 16:37:43 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • If the intake control valve is "closed" then it sure will not be pumping any fluid!

    Charles(N.C.)    Posted 05-12-2017 at 10:13:25 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • Yep,,I have the IT FO4 Repair manual.It's about worn out.When the control arm is pushing the intake valve in this means the pump is calling for fluid??? Somehow it appears the pump isn't pumping enough pressure fluid to raise the arms.This tractor sat under a shelter for about 3yrs. without moving but it had been taken to shows and lift worked.No water in the fluid but still the intake valve was stuck.I'm guessing I'll have to pull the pump "AGAIN" for an inspection when I feel better.I'm thinking it might need a pro to refurbish it for me.??? Thanks fellas.

    JMOR    Posted 05-12-2017 at 10:20:08 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • That intake control valve is on the suction side of pump, so if you close it , the pump can not suck anything in & thus can not output anything.

    R Geiger    Posted 05-11-2017 at 13:33:55 [URL] [DELETE]        [Reply] [No Email]  
  • Re: Hydraulic Lift,,,again !
  • The only way to tell if the pump is putting out the required pressure is to put a pressure gauge in the test port.
    I am not a fan of putting a new piston with o ring into an old cylinder, but if it works it works.

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