Is there a formula or chart for deriving the required viscosity for plain bearings (radial or thrust)? Or rules of thumb?
We have inherited some vertical pumps with unknown oil in them. The motor is a 30+ year old US Motors 500 hp 9600 frame, 1185 RPM motor. They have plain guide bearings and tilted shoe thrust bearings on top. The shaft and impellor weigh about 1100 lb.
The manual recommends ISO 68, viscosity index of 90+, and 284-347 SSU@ 100 °F.
I would like to verify this.
(1) If I didn't have any manual recommendations, how would I calculate the viscosity for the oil?
(2) And would the thrust bearing generally require a higher viscosity?