JD 4020 hyd January 08, 2015 11:44PM
Hello I have a jd 4020 I recently upgraded stock clutch to a double disc Crowler in doing this i went to a larger in put shaft just wondering what fellow pullers have done to maintain steering and brake pressure when clutch is disengaged on the closed centre hydraulic system of this tracter . Thanks
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Re: JD 4020 hyd January 09, 2015 01:36AM
I must be missing some thing.How did the larger input shaft change your steering and brakes. Did you change the top shaft in your trans too? Do you still have front hyd pump?
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Re: JD 4020 hyd January 09, 2015 05:35AM
I must be missing something too. You shouldn't have to do anything to the hydraulic system. It should work fine with the clutch pushed in (as fine as a stock 4020 could work with the clutch held in) unless you have something wrong in the steering valve or a high pressure leak to sump somewhere. Basically if you lose steering and brakes as soon or shortly after you push the clutch in you need to find the internal leak and fix it for it to work properly.
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Re: JD 4020 hyd January 09, 2015 02:03PM
Couldn't losing hydraulics with clutch pushed in also be a weak transmission pump?
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Re: JD 4020 hyd January 09, 2015 03:28PM
To my understanding, isn't the trans pump only for lube purposes of the shafts? However, I could be wrong; correct me if so.
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Re: JD 4020 hyd January 09, 2015 08:24PM
Did the same conversion last winter the only problem I had was fabing a bushing for the throw out bearing had to make it longer to disengage clutch.After assembly had a hard time bleeding hydraulic system of air in order to get brakes to function if you have a shop manual be sure to follow step by step to bleed system sounds like it's loaded with air,steering system on mine bled it self after some time and operating.Bleeding system is a 2 man job be sure bleeders are open and clean.
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Re: JD 4020 hyd January 09, 2015 10:04PM
Sounds to me people are working on stuff they have no idea how works. To think so: The trans pump lubes the pinion but more importantly feeds the oil cooler which in return is the reservoir for the main hyd pump.
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Re: JD 4020 hyd January 10, 2015 12:16AM
builder you are respectively wrong. trans pump takes priority in lubing pinion and top shaft gears then pushes oil thru the hyd filter and to the main hyd pump. what oil is not being consumed by the main pump is then dumped into the cooler. when u dpress the clutch pedal on a 4020 the top shaft stops turning which is what turns the trans pump. when this stops turning the main hyd pump then pulls the oil out of the cooler when demanding some oil, this is only good for a few cycles of the steering or raise and lower of the hitch arms. when the clutch is released again the trans pump will then supply the main pump with oil again. I have had 100's of these tractors split for repairs and have never ever had one air lock or have to bleed anything more than the brakes. try checking your hyd filter bypass valve. I have seen many of these stuck half open which causes a loss of flow from the trans pump to the main hyd pump thus causing it to loose steering much quicker when clutch is depressed.
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Re: JD 4020 hyd January 10, 2015 12:49AM
So you took twice as long to elaborate on about the same thing I said.
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Re: JD 4020 hyd January 10, 2015 05:54AM
The smaller stock input shaft had a splined sleeve slid over it to drive transmission lube pump constantly so it would still be lubing with clutch depressed this lube pump also acts as a pusher pump to feed oil to front pump or main hyd pump with the bigger shaft this gear pump only drives when clutch is engaged basically the main pump is just cavitating when pedal is depressed
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Re: JD 4020 hyd January 10, 2015 06:09AM
Andy, I hate to blast someone like this, but you have no idea how these tractors work. The splined shaft your thinking of is the PTO drive shaft, when you go to a two disc clutch with the big input shaft the PTO gets removed. You might be thinking of the smaller Dubuque Deeres. The real deal has it correct.
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Re: JD 4020 hyd January 10, 2015 06:13AM
Ok thanks for the opinions guys little over thought on my part
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Re: JD 4020 hyd January 10, 2015 06:24AM
Look at it this way, you learned something today Thumbs Up We all have to start somewhere Winking
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Re: JD 4020 hyd January 10, 2015 08:58AM
These guys on here are nothing but a bunch of Dumb Mu Fers ,, always gotta be jack o,s on there responses and I bet they all just use GOOGLE for the answers ; get an f ing job
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Re: JD 4020 hyd January 10, 2015 09:09AM
Quote
Shelly P
These guys on here are nothing but a bunch of Dumb Mu Fers ,, always gotta be jack o,s on there responses and I bet they all just use GOOGLE for the answers ; get an f ing job

They didn't sound like "jack o,s" to me. The responses were a great discussion and in the end we ended up with a definitive explanation of how the hydraulic system works with the clutch pedal pressed in. Sounds to me Shelly P that you should add something informative to the conversation or nothing at all. Have a nice day.
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Re: JD 4020 hyd January 10, 2015 11:10AM
[www.geraldj.networkiowa.com]
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