550 Wet Steering Clutches-Scratching My Head

[thom430]

I've been following closely Crawler123 steering clutch rebuild, so I'd like to say thanks for all the pictures and everyone else who posted. As a matter of fact, my father and I was so inspired, we tore into our 550 (straight).

This machine pushes well. It will spin both tracks under a load and still goes in a straight line. The left clutch operates and feels good. It's smooth and very responsive. The right is another story.

When pulling back on the right lever, there is very little resistance. If you hold it back (all the way) for a few seconds, it will "grab" and then turn rather abruptly. It also helps if you slow the engine speed down before pulling back on the lever.

We have the top plate and the sprocket removed but I'm looking at the brake lining and there is some wear, but it don't look that bad. I've read (and reread) the section on the steering valve and now I'm starting to wonder if there is more problem than just the brake band.

If I'm understanding this right, the steering valve just blocks the oil to the clutch pack and de-pressures or dumps the oil pressure to the clutch pack into the transmission and the clutch disengages. The brake band then engages to stop the drum from rotating. Sounds simple enough...but if the brake adjuster (which is automatic) still has room to tighten (it's still got some threads) why isn't there more resistance on the lever? Could there still be some problem with piston in the clutch pack? Why does the track keep turning?

I'll try to attack a picture and you can still see some lining on the band and I can still feel some groves. We're going to replace the lining since we are this far into machine but at this point, does anyone think the clutch pack is bad?

http://www.flickr.com/photos/41145837@N07/6502492671/
http://www.flickr.com/photos/41145837@N07/6502492893/
http://www.flickr.com/photos/41145837@N07/6502492769/

We're going to pull the piston from the clutch valve in a day or two (manual says they pull right out) and inspect them but it just seems to me that if there were a problem with this, the little dozer would have problems moving, not stopping. I'm also wondering about the two balls in the clutch pack...how do they function? It just acts like pulling the steering lever does not interrupt the oil to the clutch or even once the oil pressure is removed, the clutch does not disengage.

I've searched this and other forums for information on wet clutches and can't find much (lots of stuff on dry clutches). Am I missing something?

Any comments welcome
Thanks
Tom

[LeonardL]

I was hoping some of the 450 / 550 guys would jump in here but... lucky you... you get me! I don't know much about the steering mechanism on your machine but in your pictures it looks like the brake linkage has went over center. Have you tried to run your adjustments on the brakes and steering? On 350Cs and Ds, if the brakes are way out of adjustment ( Too Loose ) they will cause the "H" link to go over center and cause the very condition you describe. The lever will be real loose as if it has no resistance against it. Before you do any real major work you might look at this before you do.
Maybe some of these other guys will offer you a better solution. I'm just looking at what I see in your pictures. Hope this helps... and good luck!

[digitup2]

A picture may be worth a thousand words but the only photo of how close to center your adjustment mechanism is it's focused on the oils below .Like Leonard says about the linkage if it is too close to high side or over centered at this point then you will have no breaks at all.The slack adjusters would sometimes not get enough stroke to adjust the ratchet units you have to pull hard on the leavers every so often or the slack adjusters just lag at a half way point .Don't be afraid to pull hard and farther back on the steering leavers once in a while .Has someone had this steering clutch apart and put things back in wrong.Get me a side photo of linkage with leaver at rest then full stroke pull thanks .Digitup.

[thom430]

Leonard and Digitup2

Both you guys nailed it. Centrifugal force was the culprit and I should have been able to figure this out...but I didn't.

When I was a kid (early seventy's) my father was operating a D7 with a shearing blade. I remember (I was 10 or 12) that I sat on the right side of the seat and the old man on the left. When ever we went up to a tree, Pop would just pull the left steering lever, the old Cat would rev up ( I remember sometimes sparks coming from the exhaust), and down the tree would come. Whenever we had to turn to the right, he would let me do that. I had to pull the right steering clutch and then push the right steering brake. A pretty tall task for a 4 foot kid.

What's this got to do with the 550? Nothing and everything.

The "H Block" wuz not catching both ends of the brake band (just like you guys suspected). So the 550 only had a steering clutch and not a steering brake. Now JD had about another 15 years to figure out how to make both happen on one lever and I guess back in the 50's (my guess on the D7) Cat never bothered to consider how to do this or why it would be necessary...but that's another subject.

Yes, somebody has been in this steering system. The right side adjuster is less tight/adjusted than the left. We put the "cams/ears/dogs/whatever you call them back in the proper (less than over center) position and the steering lever feels fine. I can't get a fully retracted picture cause without the upper housing plate the tension makes the "H Block" want to jump up and ...over center ...again.

http://www.flickr.com/photos/41145837@N ... hotostream

We looked at the left (good) side and I remember the Old Man saying it would be bad if we let the band assembly go back in wrong (the cams over center) and that's exactly what somebody did on the right side. I think maybe somebody pulled the right steering lever before the H block was secured. I only tightened the adjuster maybe one turn and now it may be too tight.

Hard to see any other way this happened. You would think that anybody that had any business in the finals would have known this but then how did they let this machine out of their shop otherwise?

Basically the clutch was working(disengaging) but since the brake band was in effect...disconnected...centrifugal force of the drum kept the machine moving.

Seems so simple now but I didn't see it then. Big thanks to both of you for your reply. Sometimes I need a kick in the head to get my brain moving. Education comes in many forms...

Thanks a bunch, I owe the both of you at least lunch!
Tom