Zebrafive
Super Member
How did you bypass it?
Simplest way I can think of to defeat/bypass it is to remove the internal spring. Then it could never shut off oil flow to rockshaft or SCVs (if it has any)
John Deere 401C Hydro trouble
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How did you bypass it?
Simplest way I can think of to defeat/bypass it is to remove the internal spring. Then it could never shut off oil flow to rockshaft or SCVs (if it has any)
Tx Jim
New Member
I agree with Zebrafive. I've never given any thought to bypassing PC valve on a 20-55 series utility tractor. In normal hyd operation if stand by pressure gets below 1700 psi PC valve closes to give power steering priority hyd pressure by blocking oil pressure to scv & RS & FEL if equipped.
I suppose to operate tractor in the absence of PC valve one could bolt a flat plate to cover holes in the side of trans case.
I suppose to operate tractor in the absence of PC valve one could bolt a flat plate to cover holes in the side of trans case.
I bypassed the RS by plugging the rear bottom fitting going to the RS. I bypassed the PCV by connecting the inlet(from front hyd pump) to the outlet(bottom front fitting) going to FEL directly hose to hose(PCV was left out of the sytem but still attached to the transmission. Hope I'm explaining it correctly. If my RS is not functional, I can use a 12V actuator to operate my snow blower chute.
Tx Jim
New Member
SCV's can be made functional without rockshaft functioning BUT isn't snowblower mounted on 3 pt??
Zebrafive
Super Member
So forward lower fitting goes to the loader.
Lower rear fitting to rockshaft, and nothing else?
So I ASSUME, no rear SCVs?
When you had the PCV off, did it have one or two passages on the mounting side? I suspect, at least the bleed off.
Did the transmission case have passages to match?
Maybe Industrial version has the internal passage to the rockshaft that is not used (since you say rear from PCV goes to rockshaft, I ASSUME an external line), and the internal passage is somehow leaking to sump?
Have you tried bypassing the PCV and connecting direct to rockshaft, leaving loader disconnected? If this brought back problems, rockshaft or it's valve is the problem. If no problems, put in a TEE, main pump to loader and rockshaft, and plug all connections on the PCV. Leave the PCV on the tractor.
Rear SCV, is that the control for the 2/4 hydraulic hook ups at the rear for, like a direction control of the chute for a snow blower? RS is the Rear Selectors(or in your case as the Rear SCV) which I think you are referring as the rockshaft. I just need to use the wording in the right order, I'm slowly learning :thumbsup: I'll be slapping everything together as soon I get my PCV back from wear inspection. I will be connecting the Rear SCV just to see if it works from a plugged(bypassed) PCV or try a Tee. I do use the 3pt for the snowblower. There's two passages on the mounting side of the PCV including the transmission case.
Tx Jim
New Member
Rockshaft is referring to shaft that rotates in order to raise 3 pt hitch
SCV=selective control valve aka rear hyd remote aka rear wet lines(connections/breakaway couplers)
As usual I'm confused how are you utilizing 3 pt hitch with pressure control valve oil galley to rockshaft blocked off?
SCV=selective control valve aka rear hyd remote aka rear wet lines(connections/breakaway couplers)
As usual I'm confused how are you utilizing 3 pt hitch with pressure control valve oil galley to rockshaft blocked off?
It' the SCV that was blocked off. Rockshaft is not in this equation at all, eventually I will be on the same wavelength as the experts
Tx Jim
New Member
It' the SCV that was blocked off. Rockshaft is not in this equation at all, eventually I will be on the same wavelength as the experts
I was referring to your post where I thought you stated you had "pressure control valve" blocked off.
Zebrafive
Super Member
Oops! I ASSUMED RS was for RockShaft. Also called 3pt hitch.
I use SCV, for Selective Control Valve(s), for the valve(s) that control quick connectors. What you connect your chute rotator to.
So when you blocked off the rear fitting of the PCV, everything was fine?
When you connected rear fitting back to SCV(s), you had problems?
Sounds like a SCV is leaking internally back to sump. bleeding pressure off?
Is/are the SCV(s) original to the tractor? Maybe someone replaced them with ones for open center hydraulics?
I use SCV, for Selective Control Valve(s), for the valve(s) that control quick connectors. What you connect your chute rotator to.
So when you blocked off the rear fitting of the PCV, everything was fine?
When you connected rear fitting back to SCV(s), you had problems?
Sounds like a SCV is leaking internally back to sump. bleeding pressure off?
Is/are the SCV(s) original to the tractor? Maybe someone replaced them with ones for open center hydraulics?
