Auxiliary bearings

Auxiliary bearing and shaft vibration probe length (given by manufacturer)... 

As previously mentioned, auxiliary bearings are used to proteet eleetromeehanieal parts in ease of bearing overload or eleetronie failure. These auxiliary bearings are used for both radial and axial motion and are mounted on damping bands. The maximum air gap between the shaft and the auxiliary bearings is 0.25 mm (.010 in.) radial and 0.30 mm (.012 in.) axial, ineluding band defleetion of 0.07 mm (.003 in.). 

Speed is not limited by a surface speed as in the hydrodynamic bearing. Unfortunately, however, the stresses in the thrust collar pose one limit and the other is caused by need for an auxiliary bearing, which does have a limitation based on the type of bearing being used. 

The auxiliary bearing may be of the rolling element type, which is cm rently most common, or the dry lubricated bushing. The auxiliary bearing, which normally does not contact the shaft, is used to protect the Totaling components from loss of the servo amplifiers (see Figure 5-4.5). The ui -... 

Mach number, 26, IHO, 42 effect on axials, 23 L rotor tip, 100 Magnetic bearings, 204-8 air gap, 207 auxiliary bearing, 207 electromagnets, 205 laminated sleeve. 2U load capacity, 206 sensors, 206... 

An unusual solvent effect was observed in cycloadditions of aromatic nitrile N-oxides with alkyl-substituted p-benzoquinones in ethanol-water (60 40) the reaction rates were 14-fold greater than those in chloroform (148). The use of ion pairs to control nitrile oxide cycloadditions was demonstrated. A chiral auxiliary bearing an ionic group and an associated counterion provides enhanced selectivity in the cycloaddition the intramolecular salt effect controls the orientation of the... 

Asymmetric Alkylations. The use of nitrogen derivatives of carbonyl compounds (imines, imides, amides, sultams, oxazo-lines) is often the most efficient procedure for achieving a-alkylations. Chiral auxiliaries bearing heteroatoms in a 1,2-relationship appear to work best, as they have chelation sites for the metal cation. High levels of asymmetric induction can thus be achieved due to the system rigidity. Cyclic ketones have been alkylated via the lithiated enamine formed from L-f-leucine f-butyl ester (eq 1). High enantiomeric excesses and predictability of absolute configuration make this method attractive. 

How do these auxiliaries frilhl their role If we go back to the vaHne-derived auxiliary and draw the auxiliary-bearing dienophile coordinated with the Lewis acid you can clearly see that the isopropyl group shields the back face of the alkene from attack when the cyclopentadiene moves in, it must approach from the front face (and remember it will align itself to gain maximum secondary orbital stabilization and therefore give the endo product). 

Sundry nucleophiles with auxiliary-bearing electrophiles REFERENCES... 

Auxiliary-bearing organometallic donor reagents 11.3.2.1 Acyl anion equivalents (formyl, acetyl)... 

Auxiliary-bearing enolate equivalents from carbonyl precursors... 

Auxiliary-bearing enolate equivalents from carbonyl precursors 12.1.2.1 Creation of a single stereocentre... 

Reaction of ketenes with auxiliary-bearing alkenes... 

Alkyl diazo dipoles - reaction with auxiliary-bearing C=C dipolarophiles... 

DYNAMIC KINETIC RESOLUTION OF AUXILIARY-BEARING ELECTROPHILES 1156... 

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