Lubricating As valve lead screw
Here’s the Veeco document on how to lubricate the lead screw for the Mark IV As valved cracker: https://www.dropbox.com/scl/fi/s6q4is2t3x5kdi1kmn7t3/Veeco-Valved-Cracker-Lead-Screw-Lubrication.pdf?rlkey=hzijyyl67szy6pkj4xngazdpe&st=gmsmrg1u&dl=0 .
There are some issues to note with our cell on Bravo. The bearings do not come out of the housing. So here’s what I think the correct procedure to do would be.
Open the valve to a middle point, say 200 mils.
Remove the gold screw (8 503515 SCREW, BHS, SST, 2-56 in the doc), pointed to with the red arrow. It is accessible through the slot on the top side of the housing.
Remove the housing by removing the six #2-56 x 0.25 screws on the back side. This will cause the bellows to get sucked in which will open the valve which is why step 1 was opening the valve. You might hear a thunk.
When you pull the housing out it should come off with the lead screw (yellow arrow) and the drive shaft (blue arrow).
You can now unscrew the drive shaft from the lead screw (it’s left hand threaded so righty loosey).
For easier access to lubricate the lead screw, you’ll have to remove the retaining ring which sits in that notch on the lead screw. You will then be able to pull the lead screw out.
Reassemble in reverse.
