I'm new to this forum and already appreciate the info i've read from other posts. I have a 2017 Cat259d and the left drive won't move. It gave an error message )2685-8 Left Drive Motor Speed Sensor #1) and stopped working. I was able to replace the left drive motor speed sensor with a new OEM speed sensor as well as a new jumper harness to the speed sensor. The error codes are gone and don't show any active codes only logged ones. The machine will work fine except the left side won't move. Under the parameters, it will show rpm's for joystick and right tracks but never registers anything for the left track. My serial number is FTL11882 I'm willing to try anything at this point so any help is greatly appreciated.
Have you checked that the break is releasing. It's on the motor and requires oil pressure to release. Another mechanical failure could be in the planetary hub which could be locked up. Sorry, I'm of no use when it comes to electronic gizmo's.
Speed sensor code will not prevent travel. Have you checked oil level in the gearbox /hub?
He's right. You may have wasted your time replacing the drive motor speed sensor before doing tests on the hydrostatic drive system to that side of the machine. As @Tones said, is the brake releasing.? When you try to drive does one or other of the large diameter (main drive) hoses to the LH drive motor tense up.?
Ah! Great info, I didn't realize that the sensor wouldn't prevent travel. It feels like that's exactly the problem, that there is a break or something on it. I can check and see if the hose tenses up when trying to drive, I can try that today. I will also check oil level in the gearbox / hub. Thank you all so much for the reply and assistance. I will report back.
I noticed that you posted on another thread created by someone having a similar problem. Take careful note of what he found inside his drive motor, and prepare yourself for the fact that spare parts for that drive unit are not going to be cheap. See the attachment. Because there is so little oil (only about a quart) in that planetary assembly the recommendation is to change it every time you change the engine oil, despite what the factory says. It uses a full synthetic 75W/140 gear oil.
So I got a quart of the gear oil to put in it. When I opened up both plugs, no oil drained out. I cleaned the plugs off and then put the new quart in it. It seemed to take the entire quart then I noticed oil pouring out from the bottom of the back of the sprocket. Seemingly the entire quart I put in dripped out. Am I going to need to get into the drive motor?
I don't think you are going to find out anything unless you dig into it, but the fact that there was no oil in there at all (how long ago did it fall out I wonder.?) probably means you are going to find some major carnage when you do get in there. Remember the hydraulic motor part of the drive assembly is lubricated by hydraulic oil, it's the planetary reduction drive part that's lubricated by the oil that's not there any more.
Unfortunately if it is dry, and was ran dry long enough that it is now locked up, the cha css of a successful repair are exceedingly slim. You will most likely need to purchase and install a replacement drive motor/gearbox. As an example, this week we tore into a similar motor and were ready to order parts when the tech noticed wear on one of the secondary planet gear shafts. Since these are a part of the main housing, there is no way to fix it now.
Thank you guys for your replies and insight. I just purchased this about 5 weeks ago. It's been running fine and i was using it for a few hours when I parked it and then got back in it and it was locked up. I've got to get some retaining ring pliers to try and get into it today and see what it looks like. I'll report back of what it looks like. What's the main thing / wear, I should be looking for?
If it has been run with no oil, something steel either broken or a pretty shade of blue would be my guess.
Bearings in pieces, keep in mind that the main bearing set is behind the hub and not visible,
I've encountered this a few times on these exact drive motors (failed duo seal). Three times actually. I sent the drive motors off to be resealed (requires some heavy tooling... means to torque a stupidly shaped ring to 2877 ± 74 lb ft and a jig to hold everything). After roughly 500 hours two of them started making metal. Metal stuck to the speed sensors and brought on the speed sensor codes you have, contaminated the hydraulic system, requiring full system cleanout. The other one is still out there running ok for now. That's a 33.3% success rate. Now I will just quote new drive motors.
I've priced a new drive motor on the Cat website and it's outrageous. Is there an aftermarket place or 3rd party that is reputable? I found this website: Caterpillar 259D Final Drive Motor With Travel Motor Brand New Caterpillar 259D Final Drive Motor With Travel Motor - Brand New No Core Needed Free Continental U.S Shipping Call Right Now 888-866-3462 www.finaldrivemotors.com It's showing the Final Drive Motor to be $2,580.00. What do you guys' think?? I haven't been able to get into the drive motor as I haven't found any retaining ring pliers that are big enough and work as internal ones. I could order the ones recommended from Cat but not sure how much more money I should keep throwing at this. Thanks for the insight and help!