Cat 289D 2nd gear(high) tracking issue

[Acoals]

Hi guys, I have a 289D, serial 0289DVTAW01488. The symptoms I have are when the hydraulics are hot, it really doesn't show up in the winter or for the first half hour of operation. When traveling in low speed, and shifting into high, the machine will slew hard to one side, you have to input hard stick correction to compensate. When shifting back down into low gear, the machine slews hard the other direction. After shifting into high, it will straiten out, but only after rather prolonged correction. Once it is running straight, it will not run as fast as it ought to, up to 3mph slow.
I was told by the dealer I bought the machine from that this is a common problem relating to a swash plate issue in the drive motors, which Cat has remedied with a service bulletin and updated part. Basically the problem is a lazy shifting side and the PCM compensating for reduced track speeds by slowing the other side's flow.
What I am looking for is either opinions on the cause of the problem, or information on Cat's updates. My understanding of hydraulics is limited, so I am little fuzzy on what the swashplate is doing and how, (and what it isn't doing, in this case).

 

[heymccall]

Looks like two speed oil path leakage.

 

[Acoals]

Looks like two speed oil path leakage.
View attachment 254964 View attachment 254965

I am not super familiar with reading serial numbers on the dealer stuff, but is my machine covered by that campaign? My machine is TAW 0, it says TAW 1 and up. ?

 

[Nige]

I am not super familiar with reading serial numbers on the dealer stuff, but is my machine covered by that campaign? My machine is TAW 0, it says TAW 1 and up. ?

TAW1-Up (aka TAW00001-Up) is Cat shorthand for "from first machine built". Cat never uses the zeros in those circumstances.
More specifically the document covers machines up to S/N TAW02847 so your machine is included.

To be clear it is only a Service Magazine covering an in-production improvement, not a factory recall program.

 

[Acoals]

So being as the machine is covered under that update, what exactly does that updated seal kit resolve? What are the symptoms it remedies?

 

[heymccall]

All dealer support ($$$) ended in 2017 for that seal leakage. Upon reading further, the leak goes external? Maybe that ain't the issue? Is there a way to measure 2 speed pressure or leakage?

 

[heymccall]

If there is swash plate letter/ update, I don't have that deep of access.

 

[Acoals]

There is no real external leakage, and I don't really have a way to measure hydro pressures.

 

[Acoals]

So I talked to a guy locally who deals with the Cat track loaders a lot, and he told me that Cat updated the swashplate springs, apparently they get weak and cause the symptoms mine has. So for lack of any better idea as far as diagnostics go, I got the kits he recommended, Cat 487-6227.
I am debating whether to replace the swashplates myself or just take the final drive off and take it to somebody smarter than me . . . is there a service manual procedure for tearing down the drive motor, and maybe a parts diagram?

 

[Nige]

I am debating whether to replace the swashplates myself or just take the final drive off and take it to somebody smarter than me....

I thought the swashplates were in the pumps....??

 

[Acoals]

I thought the swashplates were in the pumps....??

They are, but the pumps are on the back of the final drives. I haven't torn it down yet, but I am told that the final/motor assembly has to come off the machine in order to service the pump. Just from glancing at it I would think that is how it will go, there isn't much room between the final and the machine frame.

 

[Nige]

Maybe we are talking at cross-purposes here. These are what I refer to as the drive motors/final drives. The 2-section hydrostatic pump (2nd illustration) is mounted on the back of the engine flywheel and located through the firewall almost directly behind the operator seat.
Attached the pump removal procedure and parts breakdown in case they are any use to you.

 

[Acoals]

Sorry, that is my fault, I was thinking in tunnel vision and thought pump when you said motor.
There seems to be a swashplate in the drive motor as well, I believe this one is related to the two speed. The guy here sent me a picture of his Cat parts screen, showing the part number in question.

 

[Nige]

There seems to be a swashplate in the drive motor as well, I believe this one is related to the two speed.

It is related to the 2-speed. I assume this is the one the guy you mentioned above (Post #9) recommended to change, because that's where the 487-6227 Kit is used.

Come to think of it I'm the one getting confused with another thread of a CTL that started moving on one track immediately the engine was started. The only way to stop it was to apply a steering input. That one turned out to be weak swashplate springs in the pump allowing it to drift off centre. I was was mixing up the two threads. Sorry, as you were....

 

[Chrisso]

It's easy to get confused with this setup. The piston pumps have swashplates which act normally like any other variable displacement piston pump.

The piston motors on the single speed machines have a fixed plate instead of a swash plate.

The piston motors on these two speed machines like yours do have a swash plate and their only purpose is to control the two speed function.

I was told by the dealer I bought the machine from that this is a common problem relating to a swash plate issue in the drive motors, which Cat has remedied with a service bulletin and updated part. Basically the problem is a lazy shifting side and the PCM compensating for reduced track speeds by slowing the other side's flow.

I admit it's a problem with these drive motors... I wouldn't say its that common. There has not been any update on that swashplate spring that I can see. The O-ring update above I don't think will help you unless your drive motors are leaking oil. There has been flushing spool updates which can sometimes fix the issue, 581-4919 spool is available for your machine, I've heard good reports that it has fixed straight line tracking issues but... I tried this on the last two occasions (and the exact same symptoms as yours on a D2 series machine) to no avail. Eventually resolved by replacing the drive motor.

I got the kits he recommended, Cat 487-6227.
I am debating whether to replace the swashplates myself or just take the final drive off and take it to somebody smarter than me . . . is there a service manual procedure for tearing down the drive motor, and maybe a parts diagram?

Yes, but skip to page 4 on this thread first...
https://www.heavyequipmentforums.co...rnout-aux-lines-not-pressurizing.76622/page-4
You'll find you can only go so far without some kind of fabricated stand and 3000 ft lb torque wrench, but you should be able to install the 487-6227 spring kit without going that far.

 

[Acoals]

Yes, but skip to page 4 on this thread first...
https://www.heavyequipmentforums.co...rnout-aux-lines-not-pressurizing.76622/page-4
You'll find you can only go so far without some kind of fabricated stand and 3000 ft lb torque wrench, but you should be able to install the 487-6227 spring kit without going that far.

Well, I don't have a 3,000lb torque wrench, and I don't really have the time or ambition to fabricate a stand . .
I do have a shop press, so I should be able to bypass the sketchy Home Depot clamp setup going on in that guy's pics from the burn rebuild.
I have done enough wrenching to be really wary of throwing parts at the machine because somebody said "Oh, change such and such part and it will fix it". The trouble is that I don't have a real deep knowledge of hydraulics, so diagnostics is a bit sketchy. The explanation I got from the guy who told me to change the swashplates was that the spring gets weak. He said the new springs are larger than the old ones. I am not sure, but I think he said that Cat would throw a motor at it, but that the problem is the swashplate, and that is a much cheaper fix.
At the end of the day, for lack of better ideas, I am thinking I will just take the motor apart and see what is going on in there, it would just be nice if there was some sort of procedure to get a better idea of what was involved first.

 

[heymccall]

 

[heymccall]

https://avsmanual.com/i.caterpillar/i05926265/

You may have to use Google translate, and each blue text needs clicked on.

 

[Nige]

Here's the D&A for the drive motor once you get it out.

 

[Acoals]

View attachment 255636

https://avsmanual.com/i.caterpillar/i05926265/

You may have to use Google translate, and each blue text needs clicked on.

Thank you, that is quite helpful