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fixing Van Norman 22L elevating screw oil leak

Brandenberger

Cast Iron
Joined
Sep 19, 2017
Hi,

Finally getting around to addressing oil leak from elevating screw on the VN22L knee.

I thought i'd document the details as I find them, since at least one other member indicated they also will be getting to this at some point on their machine.

I found a document a while back on this from VN, and posted it to Vintage Machinery: Van Norman Machine Tool Co. - Publication Reprints - Installing elevating screw on Van Norman 22L, 22M | VintageMachinery.org

Notes:

1) removed left side cover as instructed. It seems like the right side cover doesn't need to come off (clutch mechanism), but doing so would help with removal of the double bevel gear later.

kneescrew - 2.jpg

2) block up knee at top position so it can't fall while you're working on it.

kneescrew - 1.jpg

3) remove lock nut from top of vertical screw shaft. Access to the lockwasher prong wasn't easy, I ground a 45degree tooth onto the end of a piece of 1/8" steel bar to tap on the end of the lock. Then remove nut, I wedged a piece of brass between the bevel gears and then used a punch to start the locknut turning.

kneescrew - 3.jpg

4) at this point the screw can be made to drop through, may need some persuasion. The double bevel gear can be removed without removing two single bevel gears that mate with it... I found this to work by sliding it toward the right (clutch side) of the knee. Note: the double bevel gear has an an inset bronze thrust washer, and that thrust washer is kept from rotating by a pin on the top of the housing. So, you cannot slide off the bevel gear with the thrust washer still inset. Access from the clutch side panel may help here.

kneescrew - 4.jpg

5) removing the housing from the bottom-- I used threaded rod and nuts to pull the housing down out of the machine after removing the 4 SHCS. The housing is a pretty tight fit and might have some sort of sealant, so some pulling arrangement is better than trying to tap/pound on the top.

6) oil seal in top of housing is 1.625 OD by 1" ID. After 70 years or so, the seals aren't a lot of fun to remove, original looks like a Garlock-type part.

more later... when my oil seal replacement arrives...
 

Brandenberger

Cast Iron
Joined
Sep 19, 2017
Pictures of the thrust bearing housing, shims and thrust bearing,
with the oil seal removed.

kneescrew housing - 1.jpg
kneescrew housing - 2.jpg

Note the pin in the top of the housing which mates to the bronze
thrust washer that fits below the double bevel gear.

The shim stack is .022" on mine.

Interestingly, while the VN service directions say to coat the
shims with gasket sealer, and seal the housing itself, the shims
were not coating on mine (unsure whether service had ever been done
on the elevating screw before).
 

Brandenberger

Cast Iron
Joined
Sep 19, 2017
Elevating screw housing with new oil seal...

kneescrew reassembly - 1.jpg

Seal packed with grease (to make sure spring doesn't go anywhere) and shims and housing edge coated with Permatex Ultra Black:

kneescrew reassembly - 2.jpg

Screw reinstalled, with lock washer and nut. The housing connection to the knee casting has also been coated with Permatex Ultra Black.

kneescrew reassembly - 3.jpgkneescrew reassembly - 4.jpg

Getting the bevel gear back in place is a bit annoying, I found putting the thrust washer into the bevel gear and then mostly meshing it with the two single bevel gears and then finally adjusting the thrust washer to drop onto the pin worked.

I did not reduce the shim stack thickness due to use of Permatex, based on the theory that permatex will squeeze out when the housing is fully installed. That seemed to work--the bevel gears meshed fine.

Sealed up the two side panels, now waiting for the Permatex to cure completely before refilling with oil and seeing if it still leaks!

Not a fun job but not all that bad.

-Phil
 

Brandenberger

Cast Iron
Joined
Sep 19, 2017
Yes! This level of detail is very helpful and encouraging to other owners of leaky VNs.


By the way I can report that the leak repair was successful, no more leaks. Also, on mine there is no particular for lubricating the screw fully after the fact, so I had taken the opportunity to clean it thoroughly and re-grease with high pressure grease.
 








 
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