CAT 312C Final Drive

collins_br · Jun 18, 2017

Hi All, our 312c has developed a loud "humming" noise from one of it's drives, no grinding or tearing noises and it's working fine, it has been operating in deep muddy conditions for the last few days which probably isn't ideal. Any advice as to where to start looking would be greatly appreciated.
Thanks
Brendan.

lantraxco · Jun 18, 2017

Have you drained and refilled the gear hub? Or at least let it set overnight with the drain plug at the lowest point then ease the plug out to check for water in the oil?

collins_br · Jun 18, 2017

Thanks lantraxco, we haven't done anything yet, that's probably the first and easiest place to start alright, there is a possibility that some fencing wire got wrapped around the drive and cut the seal, it's been working in pretty rough conditions over the last few days. Do you think that contaminated oil would cause this noise?

lantraxco · Jun 18, 2017

The possibilities are many, but my first thought is a hub full of water? Checking the oil for water and also metal particles will either show a problem or pretty well eliminate the gear side from the equation I think. Hard to say what there is inside the hydraulic motor that would cause humming, piston coming apart, bad bearing, could be parking brake hanging up.... may have to open things up.

poempijus12 · Jun 19, 2017

collins_br said:
Hi All, our 312c has developed a loud "humming" noise from one of it's drives, no grinding or tearing noises and it's working fine, it has been operating in deep muddy conditions for the last few days which probably isn't ideal. Any advice as to where to start looking would be greatly appreciated.
Thanks
Brendan.

Write your contacts in this info@poempi.lt we will send you drawings. Tell us the series nimber of mechanizm (send id plate)

collins_br · Jun 19, 2017

UPDATE: We drained the oil and it didn't have any water in it but it did look metal grey!!! So we took of the cover and removed all the planetary gears and all were good. Next it was off with the track, we ran the motor and it seems good. I spun the sprocket by hand and I can hear a distinct rough bearing noise, problem found. Any advice on how to change this bearing would be a great help, should I also change the seal, if anyone has a parts breakdown it would be appreciated sr CAT0312CCDBN01139.
Thanks in advance
Brendan

lantraxco · Jun 19, 2017

Yes replace the seal.

https://parts.cat.com/AjaxCATPartLo...7zxPMbw==&storeId=21801&serialNumber=DBN01139

Should get you there for parts picture, if not we'll try something else.

You'll have to make a spanner or find a service man that has the correct one, dealer maybe, to remove the big ring nut, after that the bearings and half the seal come out with the sprocket hub. Other half of the seal stays with the motor end. Talk to CAT about the torque for the ring nut when reassembling. Better men than I will have better advice.

collins_br · Jun 19, 2017

Thanks lantraxco, I appreciate all that, the link worked perfectly, so I have my parts list now, any idea how to remove that little dowel, it is loose but there's no way to grab it!!!

lantraxco · Jun 19, 2017

No, not familiar with that one... magnet?

collins_br · Jun 19, 2017

No bother lantraxco, you've helped loads already, it's fair to say that you have saved us from a lot of sweat and cursing, ha ha. This dowel is a silly looking thing, already tried a magnet but no luck, i think I'll try a small drill bit and a self-tapping screw.

lantraxco · Jun 19, 2017

I can't tell from the parts drawing, some of those drives you drive the dowel in gently with a small hammer and punch, then you can get it out once the ring nut is removed? Doesn't look like one of those to me, but maybe you can see some clues on the real thing?

poempijus12 · Jun 20, 2017

collins_br said:
Hi All, our 312c has developed a loud "humming" noise from one of it's drives, no grinding or tearing noises and it's working fine, it has been operating in deep muddy conditions for the last few days which probably isn't ideal. Any advice as to where to start looking would be greatly appreciated.
Thanks
Brendan.

You changed the D bearings.
Now you need to adjust gears A and B.
Flange C press gear.
How much to press in. Need to do surgery, every 1/4 turn. Put a paper strip between the cogwhell tooths and turn the cogwhels.
If the paper strip is cut off, flange C needs to be released. If the paper isnt cut, the flange of the C needs to be
tightened until the paper toothbrushes begin to cut.
Or take you to the service specialists.

poempijus12 · Jun 20, 2017

collins_br said:
Hi All, our 312c has developed a loud "humming" noise from one of it's drives, no grinding or tearing noises and it's working fine, it has been operating in deep muddy conditions for the last few days which probably isn't ideal. Any advice as to where to start looking would be greatly appreciated.
Thanks
Brendan.

You changed the D bearings.
Now you need to adjust gears A and B.
Flange C press gear.
How much to press in. Need to do surgery, every 1/4 turn. Put a paper strip between the cogwhell tooths and turn the cogwhels.
If the paper strip is cut off, flange C needs to be released. If the paper isnt cut, the flange of the C needs to be
tightened until the paper toothbrushes begin to cut.
Or take you to the service specialists.
View attachment 170735

lantraxco · Jun 21, 2017

poempijus12 said:
You changed the D bearings.
Now you need to adjust gears A and B.
Flange C press gear.
How much to press in. Need to do surgery, every 1/4 turn. Put a paper strip between the cogwhell tooths and turn the cogwhels.
If the paper strip is cut off, flange C needs to be released. If the paper isnt cut, the flange of the C needs to be
tightened until the paper toothbrushes begin to cut.
Or take you to the service specialists.
View attachment 170735

Sorry, the picture you have there is for a hypoid gear, we're working on a planetary hub here....

collins_br · Jun 24, 2017

Hi all, UPDATE. Opened up the drive today and sure enough we found some fencing wire in there, seal and bearings didn't seem bad but we had a new set, so in they went, put it all back together, filled it with oil and gave it a spin, but luck is not on our side, the loud rough sound is still there. We took the cover off again and removed and rechecked all the needle bearings, but all look fine. So now it's onto the motor, any advice as to what we might find in there would be greatly appreciated also I could do with a parts breakdown.
Thanks
Brendan

Tones · Jun 24, 2017

While it was apart did you check the lash in the gears. Worn gears can give a similar sound.

lantraxco · Jun 25, 2017

Let's go back to spinning the sprocket by hand with no gears in the hub... did you try that before reinstalling the gears, see if the noise is still present? If it is, there's something still amiss where the fence wire did some damage?

collins_br · Jun 25, 2017

Tones, I didn't check the lash, but there's no real amount of wear on the gears, although it does have that sort of a sound, also this sound started all of a sudden.
Lantraxco, I did spin the sprocket without gears and it felt smooth it did have a little more resistance which I presume is from the new seals, I couldn't see any other damage from the wire, I found it lying just under the seals.
Thanks
Brendan

collins_br · Jun 25, 2017

Hi all, We took the motor off, maybe not the correct way, but we found a problem, there are 5 large ( 6" ish) bevelled washers ,that surround the piston group, one of them is broken open. So my question now is can the motor be put back on with the drive still in place and a parts breakdown would be a great help.
Thanks
Brendan

John Shipp · Jun 25, 2017

Pretty sure that when I changed a final drive on cat 312, removed motor first and refitted last, so yes to question about leaving final drive in place.

CAT 312C Final Drive

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