1979 JD 550 Dozer no power to left track

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mjeselskis
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1979 JD 550 Dozer no power to left track

Post by mjeselskis » Tue Jul 30, 2019 5:51 pm

New to the forum, but already impressed with the knowledge here. Hoping for some advice to help get back to 100%

1979 (confirmed with serial number list in FAQ) straight 550 Dozer. Have receipts from previous owner last fall for New brake bands, one axle shaft, track frame brackets, filters, oil, hydraulic fluid, etc.

The problem: The Left track has very little power. It will drive straight fine but does not turn right when I apply the right foot brake/clutch pedal. When stationary, releasing the left foot pedal alone does not cause the track to move. It tries to budge, but doesn't. I tried adjusting the valve spool under the seat and the auto adjuster on the side of the frame on the left side. I can make it worse by tightening the brake band adjuster, but can't seem to get much power to the track no matter what.

Without knowing much about this model, I'm assuming applying the foot pedal applies the brake band and also cuts off hydraulic pressure to some sort of cylinder that applies pressure to the clutch plates on the braking side.

My first guesses would be:
1) Inadequate system hydraulic pressure to engage clutch. The pressure reading on the dash is on the low side of the green side (50psi) but I'm assuming that's enough to at least partially work since the right track engages fine.

2) spool valve under the seat not allowing hydraulic pressure to clutch

3) defective "actuator" for clutch plates

4) Excessively worn clutch plates

I'm not sure how to troubleshoot the last 3. Are there test ports, and expected pressure? Is there any way to inspect the clutch plates and internals without full disassembly? I appreciate any advice.

dtoots1
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Location: akron, ohio

Re: 1979 JD 550 Dozer no power to left track

Post by dtoots1 » Tue Jul 30, 2019 6:07 pm

Welcome aboard!! It is helpful if you can access your profile and put a location n for yourself, it will show up on each post, someone may be nearby and help.
Am not sure how the steering works on your machine, most of our older ones have hand sticks or levers to operate the steering brakes. Would assume that yours operates same principle whether foot brakes or hand brakes... That being said it sounds generally like that side is needing adjustment for both the clutch and the brakes, that info should be in your manual as to how. If adjustment does not solve the problem am sure others will be feeding into this posting as well..
pictures can be posted once you email Lavoy Wilcox, postmaster@jdcrawlers.com owner of site giving him your chosen login and password that is specifically for the "pic server site" and he responds activating it. Pics can not be uploaded from cell phones...generally use pc or laptop. You will find access is under the "question and answer" forum found at the bottom page of the Board Index when logged into the crawler site. Read all the info pertaining to "Dedicated Pic Server"

Jim B
2010 crawler
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Location: western Maine

Re: 1979 JD 550 Dozer no power to left track

Post by Jim B » Wed Jul 31, 2019 7:18 am

Welcome,

Do you have a set of manuals for it so you know what the diagnostic tests are on it to pin point a cause? If you don't I suggest getting the technical manual and possibly the Operator's manual. You can use the free on line parts catalog at https://jdparts.deere.com/servlet/com.d ... anguage=19. My personal opinion is manuals are needed parts for my equipment. They give me a starting point and references to check.

From working on equipment I have found it best to have a manual to follow step by step in checking things out. The manual will have specific tests/checks to make and the specifications you are looking for in those steps. Supplement that info with input from others. Sometimes all of us are prone to forget things or mix things up between machines.

Someone with a 550 who had the same problem may give you an answer that worked for them, but I don't have a specific "do this" for you. I believe your steering clutches are oil pressure applied and pushing the pedal/pulling the lever dumps the oil from the selected steering clutch. You might have an oil supply/pressure issue on the left side, leaking seals, worn clutches so step by step checking is required to best try to pinpoint the issue. JMHO

mjeselskis
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Joined: Sat Jul 27, 2019 7:37 pm

Re: 1979 JD 550 Dozer no power to left track

Post by mjeselskis » Wed Jul 31, 2019 9:51 am

Thanks. I don't have a manual but I'll try the online version to determine the troubleshooting steps.

Jim B
2010 crawler
2010 crawler
Posts: 596
Joined: Sun Nov 05, 2017 11:36 am
Location: western Maine

Re: 1979 JD 550 Dozer no power to left track

Post by Jim B » Wed Jul 31, 2019 10:30 am

The link I posted was the site to get to the parts catalogs, those are free to use. I don't think you will find a free on line technical or operator's manual for your machine. Occasionally one can find a service or operator's manual free on line but most of those you have to purchase. Beware of many of the sites that say they have your manuals to download are scams -- they are just fishing for your info. Send Lavoy an email at postmaster@jdcrawlers.com and see if he has the manuals for your machine, he provides this site for us to use. If he can't help you with manuals, post back and I will give you a link to the John Deere manual site where you can purchase them for construction and forestry equipment.

To help ID the manuals for a straight 550 dozer, I believe you need: Technical Manual TM1108 and Operator's Manual OMT70877. The parts catalog you are looking for, and should come up with a search for 550 dozer should be PC1437. Have your serial number handy in case it is needed, sometimes it is.

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