These mechanisms are common and necessary on some big, vertical well pumps and fire water pumps. Depending on the length of the pump, it will spin in reverse on shutdown even if the check valve holds. We had deep well pumps with 400 feet of line shaft. The vacuum developed at the check valve...
I have seen Chrome plating crack or delaminate. Welding stresses can result in runout or cracks (depending on the shaft material). I agree with Artisi. I would clean up the shaft and make a new hub. Do you know the reason for the fretting? Poor alignment. Excess runout. Frequent start/stop...
I guarantee there is a balance line. The seal system could not function otherwise. I don't believe you have made any statements about the vibration characteristics. What is the primary frequency? What is the maximum amplitude? Where is the vibration highest? In which direction?
If this balance line plugged off, it would have little or no affect on thrust load. It would only result in increased pressure on the outboard seal, potentially resulting in premature seal failure.
The balance line would be external. It would connect the first stage suction to an annulus between the fourth stage suction and the non -drive end seal. Since this line is only for pressurure balance and not thrust balance, it is probably a very small line.
This pump uses opposed impellers (3 facing each direction) to balance thrust forces. It still has a balance line to reduce the pressure on the non-drive end mechanical seal. It probably uses two volutes to feed the flow into the long crossover channels from the third stage discharge to the...
Having oil present in the bearing at startup is certainly beneficial for long term reliability. But I would not classify the delivery of pressurized oil to that groove as hydro-static lubrication. At most, I might call it pre-lubrication.
I do not have access to any papers on the subject. Vertical shaft journal bearings are prone to oil whirl. A tri-lobe bearing with three axial grooves and three tapered lands is commonly used to stabilize a vertical shaft and avoid oil whirl. Do an internet search for "tri-lobe bearing"...
Tug, The axial grooves serve the purpose of breaking up whirl and whip which can pound bearings to pieces. The small hole would have have sprayed oil on a thermometer. The fact that there is now an embedded RTD does not change that. It costs money to change a design. Even if that change...
The A dimension would be measured with the springs removed or fully compressed. Cutting the nose of the cover to less than A allows the springs to be loaded, but not bottomed out.
Your pump could be purchased with or without pressure fed bearings. If it had a pressure fed oil to the bearings, the larger hole would have been the oil supply to the bearing. The smaller hole would have directed a small amount of oil to a temperature probe. There is probably a threaded port...
It is usually a single line for both. I have seen one compressor (1955 Clark) that had separate lines for thrust balance and seal chamber pressure control.
