Hydraulic System on 4230

[wi4x4man]

Hi,

I have been looking for quite some time, but I cannot seem to find out how the hydraulic system works on my 4230.

I recently purchased it to replace the ol' 4020 that I have used for years. Nothing wrong with the 4020, except I do a lot of work in the winter and I am just tired of freezing my butt off. The 4020 had a 148 loader on it, and I pulled it to put it onto the 4320 so I needed a power beyond kit.

I installed the power beyond kit behind the right SCV but I got to thinking... How in blazes does the hydraulic system actually work? There are no valves in the power beyond. And given the fact that I have an open center hydraulic valve on that is cable actuated (pretty sure it is open center anyways) how is the system going to develop pressure to the loader valve? Are the SVC's closed center, or are they open center systems? My guess is that they must be closed center?

Does anyone have a schematic out there that shows how the hydraulic systems work on these older machines. Deere has used that type of hydraulic system for years and years, and I thought I would be able to find something. But I can't.

Any help would be greatly appreciated!

 

[beenthere]

Tractordata shows closed center.
TractorData.com John Deere 423 tractor information

:welcome: to TBN

Wish you well with the new 4230.. hope to see some pics..

 

[radios1]

look here. jd432� hydraulic system diagram - Google Search more info. " Summary

The Power Beyond hydraulic system is used as a pressure/flow source for additional functions equipped with independent flow control valves. For example, planter vacuum motors, spray pumps, lift cylinders. Use Power-Beyond when:

Tractor SCV control is not needed.
Implement control valve requires external load sense signal to prevent pump operation at high pressure.
No other SCV outlet is available.

One major difference between a Selective Control Valve (SCV) and Power Beyond is an SCV has pressure/flow compensation whereas Power Beyond does not. An SCV section has an internal component referred to as a pressure compensator valve. The pressure compensator valve acts as a pressure regulator in the SCV section to maintain constant flow regardless of any other hydraulic function used.

For example, a hydraulic motor running on SCV #1 may require 10 gallons per minute of hydraulic flow at 1500 psi. If SCV #2 is engaged to run another hydraulic function that requires 6 gallons per minute at 2000 psi, the compensator in SCV #1 will balance this pressure change from hydraulic pump and maintain steady operation of the hydraulic function from SCV #1."

 

[wi4x4man]

Well that is what I figured... that it would be a closed center type of system. And I do know how these particular SCV's work in terms of the pressure / flow compensation. But how does the hydraulic pressure build? Is there a signal that goes back to the rotary piston pump that destrokes it when not being used to keep system pressures low?

The more I think about it, the control valve on the loader must be a closed center. The only reason I say that is because the supply came from a T fitting forward of the brake pedals, where the rockshaft gets pressure from. The return went into the filter cover. So if the valve was open center, the rockshaft system would not get power to raise or lower.

I guess my main concern is that I cannot find hydraulic schematics. I might bite the bullet and get the repair manual for it as I would also like the electrical system schematic. Otherwise everything else is self-explanatory and easy to figure out. But if someone has a hydraulic schematic for these Iron Horses I sure would love to see it.

 

[wi4x4man]

Here is a picture of the Three Amigos... lol

 

[Tx Jim]

Well that is what I figured... that it would be a closed center type of system. And I do know how these particular SCV's work in terms of the pressure / flow compensation. But how does the hydraulic pressure build? Is there a signal that goes back to the rotary piston pump that destrokes it when not being used to keep system pressures low?

The more I think about it, the control valve on the loader must be a closed center. The only reason I say that is because the supply came from a T fitting forward of the brake pedals, where the rockshaft gets pressure from. The return went into the filter cover. So if the valve was open center, the rockshaft system would not get power to raise or lower..

PBY block simply has an orifice that provides pressure & an orifice for return oil. I was thinking PBY should be mounted on LH side of rockshaft housing. When hyd pressure reaches a set pressure known as "stand-by" which is 2250 psi from the factory then pressure inside crankcase of pump pushes the 8 pistons away from the rotating pump shaft therefore pumping stops. When pressure in hyd system falls springs push pistons back against rotating shaft & pumping oil commences. Pumping is controlled via the stroke control valve. Control valve on 148 loafer mounted on 4020/4230 should be closed center type.

 

[wi4x4man]

Thanks for the info! I never knew that is how the pump operated. But now that you say that, it makes sense. And quite frankly, that is a really slick way of thinking. I always get a kick out of the ingenuity of people back then. To think that the design came out in the late 50's and it was all done by hand (calculating, designing, & building) is impressive. It is too bad that so many of those skills have gone away. Thanks!

 

[Tx Jim]

Radios 1
May I ask which valve in 4230 scv housing that you're referring to as flow compensation & your definition of what flow compensation does on a JD closed center hyd system?
Thanks you,Jim

 

[Tx Jim]

Thanks for the info! I never knew that is how the pump operated. But now that you say that, it makes sense. And quite frankly, that is a really slick way of thinking. I always get a kick out of the ingenuity of people back then. To think that the design came out in the late 50's and it was all done by hand (calculating, designing, & building) is impressive. It is too bad that so many of those skills have gone away. Thanks!

You're welcome
JD closed center is/was very good system although it has some quirks. I remember attending JD sales & service meetings when I was employed by JD dealer explaining how great the system was & how much fuel it saved compared to open center hyd systems. Later more hyd functions were added so frt hyd pump was rarely out of stroke for very long period of time so fuel savings went down the toilet. Fast forward to today & many JD tractor models have open center hyd systems.