Centering sleeves

In normal operation, a sleeve bearing provides a uniform oil film around the supported shaft. Because the shaft is centered in the bearing, all forces generated by the rotating shaft, and all forces acting on the shaft, are equal. Figure 44.47 shows the balanced forces on a normal bearing. 

Lubricating-film instability is the dominant failure mode for sleeve bearings. This instability is typically caused by eccentric, or off-center, rotation of the machine shaft resulting from imbalance, misalignment, or other machine or process-related problems. Figure 44.48 shows a Babbitt bearing that exhibits instability. 

Machine-trains that use sleeve bearings are designed based on the assumption that rotating elements and shafts operate in a balanced and, therefore, centered position. Under this assumption, the machine-train shaft will operate with an even, concentric oil film between the shaft and sleeve bearing. 

Shajts. Shafts shall be suitable for hook-type sleeve. Shaft material shall be (SAE 1045 steel on Duron and 316 stainless steel pumps) or (AISI 316 stainless steel on CD-4MCu pumps and 20 stainless steel pumps). Shaft deflection shall not exceed. 005 at the vertical center-... 

A safety (cotter) pin (2) with a pull ring is inserted thru a pair of holes in the arming vane to prevent it from turning. A short wire with a safety clip attached is inserted thru a 2nd pair of holes in the arming vane. The arming pin (4), [which is attached to the vane (1)], extends into the center of the fuze thru the striker (6) and sleeve (7), both of which are locked together by two steel balls (12) located in two holes of the striker (6). Each ball is held outward in a recess of the sleeve... 

The most extensive test which has been made of this conduction model for thermal explosion is to be found in the work of Vanp e on the explosion of CH2O + O2 mixtures. He used a calibrated thread of 10 per cent Rh-Pt alloy of 20 m diameter (jacketed by a 50-m quartz sleeve) suspended at the center of a cylindrical vessel to measure directly his reaction temperature during the induction periods preceding explosion. By Uvsing He and Ar as additives and vessels of different diameters he was able to verify the dependence of the critical explosion limits on vessel size and on thermal conductivity of the gas mixture. In addition, he was able to check the maximum predicted temperature at the center of the vessel just prior to explosion and also the value of 8c = 2 [Eq. (XIV.3.12)], the critical explosion parameter for cylindrical vessels. Finally, with a high-speed camera, he was able to show directly that the explosions in this system do start at the center, the hottest region, " and propagate to the walls. 

All three bushings are. 7" thick with center holes threaded 3/4" x 16 TPI to fit the fronts of the inner sleeves. The front shoulders of all three bushings are 1 9/16 OD X 20 TPI to accept the threaded front... 

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