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Discussion Starter #21
I'd would love to see more photos of the cylinder, mounting and hose routing. I'd really like to know who manufactures the cylinder and their part number. With that and knowing that the pre-charge is 950 psi, all the hard work is done. If that isn't possible, then dimensions of the cylinder would be great. Do you have details of the metric fitting, like thread size/type on each end, part number, source? Looks like the hoses are 1/4"? Sorry for all the questions, but you are the only one I've found who has reported success in doing this with a tractor that has an internal rockshaft piston. I'd be sourcing and installing this myself.
 

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The next one I will get from parker industries. I can get them local dont like to use china.

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Discussion Starter #24
The next one I will get from parker industries. I can get them local dont like to use china.

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Thanks so much Snow rush for the info. I'm about to drill and tap the plug for a pressure gauge to get the pertinent pressures to properly size the accumulator for my snow blower. Can you tell me the size of the accumulator John Deere included in their kit you got for the 4520? How did you arrive at the 950 psi pre-charge?
 

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We are still playing with the pressure 950psi is high,we are going to lower the pressure when we get the gauge for the accumulators. I was told to 800psi from green tec Canada. The working pressure for the system the 4000 series tractor is 2500psi. I was told that if you raised the 3pt with a load on it .and then cracked the accumulator valve to let the nitrogen out.when the 3pt hitch moves.close the valve
950 psi is to much .you don't want less then 25 percent less of the working psi in the accumulator. Will damage.

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Discussion Starter #27
See photo for size . Picture of end of box

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Interesting process to tune the pressure. I like it!

It looked to me that the picture you posted was of a cylinder, not an accumulator. Hydro Custom apparently OEMs the accumulators for Deere so they don't have any literature for them as a product line. Since I saw a stroke on the box and "Hydraulic Cylinder"(no other manufacturer lists stroke for accumulators) I assumed the box was for a cylinder and mistakenly posted. If it is really the box for an accumulator, then I have what I need. Did you end up using a flow control valve to control bouncing and response or have you found it unnecessary? I'll be trying it without to begin with, but will plan for adding it.

I've seen a YouTube video of a piston accumulator in action, but it seems to me that it was grossly oversized and induced a several second delay when cold. Bigger is better for shock absorption, but is slower to respond. Smaller has a quick response, but is less effective at shock attenuation. Pistons are pretty much bulletproof(if mounted vertically), but limited to 250ms or slower response time. Diaphragms are much quicker to respond and position insensitive, but more prone to failure due to the nature of the flexing of the elastomeric diaphragm, and not repairable. I'll keep this thread updated with my findings for sizing and performance of an accumulator for the 3520 which is very similar, hydraulically to your 4520.
 

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Just an FYI, JD P/N L210047 is a straight 1/4" (04) Male ORFS x male M8 adapter fitting $14.39
 

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JD parts lists LOTS of accumulators, both diaphragm and piston type.
An example of a piston type is P/N AN277769. 8.858" long, 2.380" OD, 3/4" O ring port, precharged 1000psi, weight 5.42lbs price $216.04
 

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Discussion Starter #30
JD parts lists LOTS of accumulators, both diaphragm and piston type.
An example of a piston type is P/N AN277769. 8.858" long, 2.380" OD, 3/4" O ring port, precharged 1000psi, weight 5.42lbs price $216.04
Zebrafive:
Where are you getting the details for the JD part numbers? The JD parts catalog only gives a name for the parts, never any size or design details.

Unfortunately, all accumulators are not created equal. One needs to know the internal volume and type of accumulator to properly fit it to the system. Too small and you run out of fluid during a typical cycle causing damage to the diaphragm or piston. Too large and the response time slows, size and parts costs go up. In my case I'm looking for one with about 20 to 30 cu. in. internal volume. Without knowing the size and stroke of the rockshaft piston, I can only make an estimation of the size needed. Ideally, I'd like my blower to float within a 6-8inch zone while transporting it fully lifted. If I only knew how much fluid the rockshaft piston displaced, I could accurately calculate the accumulator size.

I tapped into the oil reservoir of my 3520 and determined the pressure to be 1500-1600 psig when the 910# blower was lifted fully(24" behind the lift arm pins). The max operating pressure is 2500 psig. I just wish I knew more about the dimensions of the integral hydraulic piston and linkage. With what I know about the system, I'll be installing a .35 liter (20cu. in.) Parker accumulator. The precharge should be somewhere between .6 to .9 times the median working pressure (900-1350 psig). Pretty sure most places just go with .5 times the max system pressure(1250 psig).
 

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Info came from JD parts. They also had internal volume, I just did not post that. They also had precharged and uncharged.
You could also choose between piston and diaphram types.

When I bought the loader suspension system for my JD 6415's JD 640 loader the accumulator came uncharged. The dealer charged me $70 to add nitrogen.

Volume for P/N AN277769 is listed as .085Gal, which converts to about 19.6 cubic in.
 

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In JD parts look for (on left on the home page) MAINTENANCE PART SEARCHES. Then in that box, click on the last search; "by Part Specifications" . That will open a new window. In that window click on accumulators. You then have a few more options and end up with listings of ALL P/Ns for the options you choose.
 
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