Bearing runout

Oscillation in normal force due to small temperature fluctuations in a viscous polyethylene sample (Franck, 198Sa). Tiny vertical oscillations in the rotating shaft (bearing runout) can lead to similar oscillations in the normal force. 

The bearing runout problems discussed above highlight the importance of mechanical construction in rheometers. Clearly a small departure from 90° between the axis of a small angle cone and the surface of its plate will cause the shear rate to be higher on one side than on the other. The same is true for eccentricity in the axes of concentric cylinders (eq. 5.3.43) but with typical gap sizes (> 0.5 mm), alignment is less critical than with the cone and plate. 

Various protective instruments are used to provide a shutdown signal (to a fast-acting trip valve at the expander inlet) that senses various things, such as overspeed, lubricant pressure, bearing temperature, lubricant temperature, shaft runout, icing, lubricant level, thrustbearing load, and process variables such as sensitive temperatures, levels, pressures, etc. However, too many safety shutdown devices may lead to excessive nuisance shutdowns. 

Axial proximity probes are another means of monitoring rotor position and the integrity of the thrust bearing. A typical installation is shown in Figure 21-11. In this case two positions are being monitored one at the thrust runner, and one at the end of the shaft near the centerline. This method detects thrust-collar runout and also rotor movement. In most cases this ideal positioning of the probes is not possible. Many times the probes are indexed to the rotor or other convenient locations and thus do not truly show the movement of the rotor with respect to the thrust bearing. 

Vectorial subtraction of slow-roll (300-600 rpm) total electrical and mechanical runout is permitted by the API rules. Vectorial subtraction of bearing-housing motion may be Justified if it can be demonstrated to be of significance. 

Concentricity Term to describe two circles or cylindrical shapes having a common center and common axis, such as the inside or outside diameters of a barrel or outside diameters of the surface and bearing surfaces of a screw. Deviation from concentricity is referred to as runout. Also refers to the relationship of all inside dimensions to all outside dimensions usually expressed in thousands of inch or millimeter FIM (full indicator movement). Deviation from concentricity is usually referred to as a runout. The concentricity should allow for the maximum part tolerance. The geometry of the part should help indicate the tolerance applied. 

Electrical and mechanical runout of the rotor surfaces to be observed by vibration probes shall be determined and recorded. The runout shall be determined by rolling the rotor supported by V-blocks positioned at the centerhne of the bearing journals while measuring runout with a noncontacting vibration probe and a dial indieator simultane-... 

The runout of shafts and assembled rotors measured with the shaft or rotor supported on V blocks or bench rollers adjacent to its bearings shall be within the limits given in Table 5-1. 

Rigidly-coupled vertical in-line a) Motor construction (6.1.6, 6.1.7)) b) Rotor stiffness (5.6.9) c) Product-lubricated guide bearing (5.10.1.1) d) Shaft runout at seal (5.6.8, 5.8.5)... 

Use the dial indicator to measure the axial and radial run-out tolerance of. Drive bevel gear flange. Max. Axial runout 0.1mm Max. Radial run-out tolerance 0.1mm Remarks It should check the big and small bearing of drive bevel gear when the runout is more than 0.1mm. 

Remarks It should ensure that the bearing is adjusted correctly before the measurement. maximum circular runout 0.11mm... 

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