*Be sure to check out the part 2 video above showing the tilt pad motion and some of the common bearing terminology.
Background:
Video 1: This animation was made using SolidWorks Composer (my first try), and everything was modeled by me in SolidWorks. The tilting pad bearing falls under the fluid film journal bearing category. Tilting pad journal bearings are chosen for small and medium rotors operating at medium to high speeds. The main advantage of tilt pad bearings over fixed geometry bearings is the absence of oil whirl since there are no destabilizing cross-coupling forces. The cross-coupled stiffness is reduced greatly since each pad can have its own pressure profile. The rocker back style has the advantages of being the simplest and cheapest to manufacture over other tilt pad bearing types. One disadvantage of tilt pad journal bearings is that they have higher parasitic losses as opposed to other bearings, like ball bearings.
Video 2: This animation is part 2 of my "rocker back tilt pad bearing" project. I made this animation to highlight some of the main components that make up this type of bearing. I also tried my best to show the pad tilting motion along with the oil wedge that forms in order to lift the shaft during operation, and prevent metal-to-metal contact. Note: that I exaggerated the bearing-to-shaft clearances in order to make the oil film noticeable.
My bearing design:
-Type of pivot: rocker back pivot (line contact)
-Pivot offset: 50% centrally pivoted (typical pivot offset ranges from 0.50 to 0.65)
-Preload: 0.25 (typically ranges from 0.15 to 0.75)
-Load vector orientation: load between pads (the other option available is known as load on pad)
-L/D ratio: 0.7
-4 pads (aka shoes), two of them instrumented for temperature sensing (either thermocouple or RTD)
-Pad material: Steel backing with Babbitt lined pads
-Babbitt type: grade 2 ASTM B23 w/ bond line thickness of 1.5 mm.
-Pad sensor location (circumferential): within the recommended 75% of the total pad arc length from the leading edge (where the maximum pressure occurs)
-Pad sensor location (axial): at the pad axial centerline (only for self-aligning pad types) where the maximum pressure and temperature occur
-Rotation of the shaft is shown via marking on the shell
-Dowel pins are used on the split line for positive realignment
-Socket head cap screws are used to join the bearing shell halves
-Installation type: pin located design using an anti-rotation steel dowel pin. Usually there are three type of configurations: pin located, flange located, and bolted flange located
-Method of lubrication: evacuated design (other option is known as flooded). The evacuated design helps to reduce bearing oil temperature by eliminating entrapped hot oil.
-Oil inlet supply: using directed lubrication with a conventional spray bar (other common choice is using a spray-bar blocker).
-Oil discharge control: using open end seals (50 mil inner seal tip diametrical clearance) and a slot on the lower fixed end seal.
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