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John Deere 4020 hydraulic pump drive shaft coupler R34359

T

TigerPaw4020

Member
I'm looking for the hydraulic pump coupling drive shaft for my 4020.

The bolts that clamp the split on my coupling worked loose and allowed the coupling drive to wear and eventually spin on the hydraulic pump shaft. The pump shaft is still in good shape but the internal splines are eaten out of the drive coupling shaft and it won't tighten enough to grip the pump shaft splines.

If anyone has one they've parted out that they'd like to sell, I'd be obliged. Not only does my Deere dealer not have one, but if he did, or could find one it would be pricey.

JD part no. R34359, or old no. AT42311.

I think it also fits the 3010, 3020, 4000, 4010, 4020, 5010, Industrial 500, 500A, 600, 760, and Skidder 400

I only need the internally splined coupler drive shaft. I don't need any of the other coupler parts.

It is 4.370" long with 14 splines.

I thought I would check here first and give you guys a shot before heading over to Ebay. Thanks in advance.
 
Is it worth the risk of using a partly worn coupler on the worn
splines ? Even a new coupler may not properly clamp down on
the worn splines.
$91 is pretty reasonable to reduce the chance of down time
again.
 
What other option would he have? $91 isn't going to put a new shaft in his pump. It is a complicated job. At the least, he'd need a lot of hours of labor, a new pump shaft, new pump kit, probably new bearings on the pump shaft, etc. It is an awful job to try to replace a shaft in a Deere 8 cylinder pump. If he has moderate shaft wear - a new coupler that has the take-down screws will adjust for wear.
 
Spring for the new coupler. The aftermarket ones are fine. Check the bolts periodically as the splines may "wear in" a little. I have done this many times with no problems. You already have a used coupler...
 
I don't have a used coupler, I have a completely worn out one. The internal splines are completely gone in the coupler. The pump shaft however looks like it has very little wear. I don't understand how that is possible, but I am looking at the parts and that is what happened. I guess the coupler is much softer than the shaft. I'm just glad that it happened that way instead of the opposite.

When I put it back it will be with longer bolts that go all the way through and a lock nut to keep them from coming loose.

Thanks for the info guys, but I guess no one has one for sale.
 
Not an uncommon problem.Deere used a cast coupler and a steel pump saft so the coupler would wear rather than the pump shaft.A salvage yard would have what you need but I would go myself rather than have them ship it as they might give you one that is worn.In your position I would get a new one from A&I.We have a 2520 that every 5-6 years it eats a coupler and I have replaced them on others as well.It sems to me that when the bushings get wore it lets the coupler hammer some and can ruin the splines even if the clamp bolts are tight.
 
Yeah, slight misalignment issues could wreak havoc also. I will check that when I put it back together.

Anyhooo, I found a used one parted out on ebay for $50. Pictures look like the splines are perfect. We will see.

Thanks everyone.
 
Something does not sound right ? How many hours do you put on it in 5-6 years ?
No way should it have that short of life ?

Are you using a torque wrench to tighten all the bolts up ? New coupler,alum halfs,buhings and bolts all at replacement ?
 
Ebay came through this time.

$50 used part was like new.

Fit perfectly and I'm puttering again.

Now if I can just get all these ice storm damaged trees and limbs cleaned up before something else breaks I'll be happy.

I guess that is the joy of owning a 47 year old tractor. I work on it more than I work with it.
 
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