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4020 powershift fluid debris

N

Northvale - PA

Member
so, I was mowing hay with the 4020 powershift 3 nights ago and the transmission was losing power at certain times. Basically, at the bottom of a hill turning to go up, as I hit the brakes and turned 90 deg, in either 3rd or 4th gear, the transmission indicator needle would go down from full power to about 75%. Down shifting into 2nd, the needle would go right back to full power. I changed the filters and fluid about a month ago but had never checked the sump screen. Today, I drain everything down and pulled the sump screen. There was a little stuff caught in it. But, there was also much more debris that flushed out the drain holes. Some pieces of flat brown stuff, black rubber looking chunks and some small metal filings. Is this bad news? Is it brake linings I am reading about? Did opening the drain plugs flush this junk off the sump screen? Tractor has 6500 hours on it, I've had it about 10 years. First time with these symptoms.
 
Debris like that could be either from lined plates in the powershift, or brake linings from the brakes at the wheels.

Either way NOT good. Metal filings will only get worse because parts intended to have lining on them are now running metal-to-metal

Might as well start by having a look at the brakes.

BTW, the gauge doesn't indicate "transmission power", but rather operating oil pressure for the powershift transmission, used to engage the clutches and "brakes" inside the transmission used to select various speeds.

If it shows less pressure in certain "gears" that will point to which individual parts in the transmission are failing.

There's a chart in the SM showing which clutches or brakes are active in each "gear".

(Just to clarify we are talking about two different
brakes" here, the "service brakes" at the wheels and "brakes" used to lock certain parts of the planetary transmission to achieve the desired speeds/"gears".)
 
Yeah, I never thought of that, Jim, however, sounds he DOES have an excessive amount of debris and filings in the transmission.
 
So, the worst of the debris is brown flakes. Sort of looks like that older brown electrical insulation material.It is thin & flat.
 
I have fought that crud in my 4020 for 15 yrs,.. you need new brakes ,even though they probably work fine as mine did ,. water in the fluid will cause them to come apart ,I think the water was getting inaround the brake pedal seals..just best keep the deer under roof ..the trumpets will have to come off the tranny ,it really aintthat big of a deal if you have jacks and stands,, but not a job for me.. ,muther deer hit me for 1800 to fix mine and flush and clean,.that included new front hyro pump that was repaired under warranty 5 times ,,the pump kept leaking and blowing seals ,, not sure why ,..they also put a magnet brick in my 4020 tranny ,,. I would bet they get pretty fuzzy with contaminants over time ,. my 4020 gets new oil and filters every year , all I use it for is the round baler,.
 
Why use confusing terminology?
A powershift as I understand it is basically an automatic transmission that is shifted manually, and has no full automatic function. Should be fairly simple matter of hydraulics, and should be a reliable unit - being as it has no governor or automatic shifting programming.
As I have been rebuilding automatic transmissions all of my life, I suggest you call clutch pack exactly that - CLUTCT packs. Not "brake" packs. Bands are just called bands - short for BRAKE bands. That nomenclature comes from the fact that they generally brake a spinning component to effect a change in power flow through the planetary gear sets. That way, service brakes can be brakes, clutches can be clutches, and bands can be bands.
 
"I suggest you call clutch pack exactly that - CLUTCT packs. Not "brake" packs"

Jimg, the terminology is John Deere's, NOT mine.

There's NO bands used in those powershifts and the "clutch packs" that stop movement of parts of the planetary gearsets as needed for speed changes to occur are called "brakes" by the company that made them. Clear as mud? I hope?
 
Well, it really does confuse things. To a novice that has no understanding of planetary gears and how they produce different gear ratios, it must be very confusing. Add in service brakes that apparently run in oil, and the picture gets even muddier.
Now you have a farmer with a book in one hand and a tool in the other, and there is a "bambi in the headlights" look on his face trying to figure out what brakes they are talking about.
 
That's why I was very specific in my post to differentiate between the "service brakes" at the rear wheels from the "brakes" in the PS transmission.

And there's NO worry for any farmer with a DEERE factory SM mistaking which brakes are being discussed. Those manuals are THOROUGH.
 
I agree with Bob. The 8 speed powershift transmission basically consists of a clutch pack in the front and a planetary brake pack in the back and another smaller clutch pack in the rear side of the brake pack. They are called planetary brakes and that is what they do, they brake the outer planetary ring gear to change speeds. Trying to compare it to a car or truck transmission is what will make it confusing to most people. They are two completely different setups. The biggest difference is the fact that there is no torque converter in the JD powershift. They are a very simple and reliable transmission, but when things go south it gets expensive fast! A total rebuild can get as high as 8-10K I suggest a pressure test in every gear and if a problem is suspected not to put off the repair. If caught early it can be a BIG difference in the bill.
 
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