M936 crane winch gearbox

[charlesmann]

If this has been posted before, sorry for the duplicate topic. I did try the search function using different key words but no luck.

After installing the winch motor, i decided to drain and service the gearbox. When i rmvd the gearbox drain plug, a milky white mixture came flowing out. Instead of filling it with fresh oil, i poured in a gallon of mineral spirits to help flush the water mixed gear oil out. I noticed leakage coming from between the gearbox and the cable drum. I used the square drive on the winch motor to turn the gears in the box to help rinse some of the contaminated oil. As i turned the gears, i noticed the leak got worse, the lightened up then worse. I stoped when the leak was as lite as possible and pulled the plug again.

I let it drain for a couple hours before servicing. I put 1 gallon of lucas oil stabilizer and 3.5 qts of 80/90 gear oil.
I didnt notice a leak till after cycling the freshly resealed motor numerous times, and as i was running the winch, i noticed the cap on the operator side of the drum wobbling in an egg shape motion and I assumed bearing are worn out at both drum support locations.

While i was picking my tools up and gathering up the used pig mats, i took a peak between the gearbox and drum and noticed that even with the lucas, it was still leaking a little. The leak explains how water mixed with the gear oil and why it was low again after i added 2 qts several months ago.
With the motor leaking, im understanding why there was so much oil on the deck, a mix of hyd fluid and gear oil, but i was thinking it was all hyd fluid.


Has anyone replaced the bearings and seals between the drum and gearbox and the operator side of the drum support? I dug in to the parts tm, and from what im gathering, the bearings are not ball/roller type, but more like babbit style oil impregnated bronze bearings.

I also looked at big mikes, memphis, eastern and oshkosh for the seals and bearings, and no luck, nor was there any alt p/n cross reference on wb parts. Parts show either garwood winch or us tank command, so a bit of help sourcing the bearings and seals would be appreciated.

TM used is 9-2320-272-24P 2 WP 0513-1 through 5, items 13 (bearing, sleeve nsn 3120-00-740-9800 and 56 (gasket) nsn 5330-00-419-5875 between gearbox and gb mounting plate. Items 48 (bearing, sleeve) nsn 3110-00-504-8929 and 47 (bearing, thrust washer) nsn 3120-01-085-3338 between gb mounting plate, drum support plate (operator station side) and drum, and last item, 50 (shim) nsn 5365-00-185-7835. The cover gaskets, i will make, since the above mentioned suppliers are out of stock for several the gaskets, depending how far i have to tear the gearbox down to replace the seals and bearings.

 

[KN6KXR]

No lip sealers or roller bearings for the drum. Wow. The bushings are bronze 932 and the gaskets are neoprene. As far as I can tell you're supposed to grease it A LOT and it just..... leaks. By design. Only two lip seal on the whole thing item 7 at the end of the worm drive shaft. Plain gaskets at the drum shaft. How strange. Is it possible it's supposed to be so full of grease not to leak?

No luck for me either on the cross reference. Luckily 932 bronze is common and might be able to be made by a shop that does so without drama. They may be able to work of the spec posted in the NSN. I would not switch to oilite bushings they can't withstand higher loads stick to machined brass. For the gaskets they are neoprene that can be had in sheets of whatever you like and just cut to size so not worth chasing.

I find this interesting because I found my rotator gearbox gear to be toasted and it's currently apart on the bench. After I get that rebuilt my immediate next inspection will be this gearbox.