jd 690a undercarriage

Did John Deere out source the undercarriage on the 690a excavator to another crane manufacture and is the parts enterchangable with another manufacture. Also what is that type of crawler track called.

JD never built their own undercarriage. I think Cat are the only ones that make their own undercarriage. There are several companies that build undercarriage, either for OEM's or as replacement. The chain part is called the rails. You'd have to look at an undercarriage chart to see if it matches up with something else. There's few undercariage guys on here and I've seen a chart but can't remember what site it's on. Try googling undercarrige or JD 690A undercarriage.

Try ACR Equipment in Cleveland, Ohio. I purchased some bushings for the drive tumblers on my 690 from them a couple years ago. They had pins, drive tumblers, and most other parts at that time.

What are the drive tumblers? A JD 690 has crawler tractor type undercarriage with hydraulic motors to drive them. Old shovels and draglines used drive tumblers.

Per my recollection, the 690A had flat tracks. From my Link Belt crane days, they can be welded up and/or new drive lugs welded on. I doubt if you want to buy new track shoes for such an old unit as you would have more in it than it would be worth.

I believe the 690B and up had tractor type undercarriage.

The 690A used crane type track shoes and drive tumblers......AKA flat tracks.

From the brochure it looks like it has flat pads and smaller chains and sprockets to drive the larger tracks. It still uses hydraulic motors for each side. The old P&H machines of the era were the same way. I new a guy that 6 P&H machines. 5 418's and one newer 1250 that was an updated 418 with crawler tractor type undercarriage. On the older machines he built up the drive sprockets with 7018. The real old machines used tumblers for drive and steering. I'm not sure what he means by tumblers on 690A.

The 690 and 690A did have the crane-style undercarriage with 200HH chains running from the motors to the drive sprockets. The 690A was identical to the 690 except for a diverter valve that would let you split the hydraulic flow between the boom functions and the track motors so you could run both at the same time.
The bronze bushings that support the shaft that the tumblers and drive sproket sit on were worn out on my machine to the point where the casting itself was worn too. I found a used casting after a lot of looking, but bought the bushings from ACR. They were $50 each or so, whereas JD wanted $200 if they could find one. ACR also had shoe pins for ~$10 each (basically a piece of 1" round stock) and had new tumblers for $525. I resorted to welding mine with 7018 - it took about an hour per tooth. Bought a self-darkening welding helmet for that project, and boy was it worth it! Also had to make new track tensioner screws as mine had bent and lost their thread pitch when I tried to straighten them. Not many lathes can make that coarse of a thread (either 3 or 4 tpi). The square head I welded on after.

Now I know what you mean by drive tumblers. They can be built up with 7018 but a little preheat aroung 400 deg. would be good. For longer wear you could use Stoody build up rods instead of 7018.

I deal with a company out of Cleveland Ohio called Pyramid Parts www.PyramidParts.com . I've called them and they deal in all kinda of aftermarket undercarriage parts for older and newer crane-style undercarriages, but nothing for the chain-style. They don't always stock real old stuff but they can manufacture for a fair price. I also know they can get a lot of parts that are not listed in they're parts pages or on they're web site. They're old parts book i have lists the JD690 along with a bunch of other manufacturers like Koehring, Lima, Link Belt, Insley, Lorain, Bucyreus, Manitowoc, Drott, Northwest, P&H, ect. I'd give them a try 216-642-9600

It s been a long time since you posted with the pictures of your 690a repair. If you are willing, I would like to get more information from you concerning your repair and technique. I just purchased an old machine with almost identical problems as it looks like you may have dealt with. Please let me know. Thank you