Electromagnetic bearings

Aerostatic bearing Angular contact ball bearing Ball bearing Electromagnetic bearing ... 

Electromagnetic bearing Electromagnetically levitated spindle Magnetic spindle... 

As the air gap between these two parts decreases, the attractive forces increase electromagnetic bearings are inherently unstable. A control system (Fig. B-6) is needed to regulate the current and provide stability of the forces and rotor position. 

In a radial active magnetic bearing, the rotor is held in position by electromagnets located on the stator (Figure 6-3). The rotor-to-stator position is constantly monitored by sensors that communicate with the electronic control system. If the rotor deviates from its position, the control system adjusts the current flow to the electromagnets to return the rotor back to its proper position. 

An active magnetic axial bearing consists of two stators and a rotor disk (Figure 6-4). A sensor located at the end of the shaft monitors and maintains the rotor position between the two stators. The principle of operation is the same for both axial and radial bearings any deviation from the normal position of the rotor is communicated to the electronic control system, which adjusts the electric current going to the electromagnets to correct the rotor position. 

The magnetic bearing is made up of a series of electromagnets located circumferentially around the shaft to form the radial bearing. The electromagnets (Figure 5-42) are laminated to limit the eddy current losses. The shaft must be fitted with a laminated sleeve (see Figure 5-43) for the... 

Figure 5-42. Radial magnetic bearing with a view of the circumferential electromagnets. (Courtesy of MafhTrem Corp.)...

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... 

It is to be expected that the equations relating electromagnetic fields and potentials to the charge current, should bear some resemblance to the Lorentz transformation. Stating that the equations for A and (j> are Lorentz invariant, means that they should have the same form for any observer, irrespective of relative velocity, as long as it s constant. This will be the case if the quantity (Ax, Ay, Az, i/c) = V is a Minkowski four-vector. Easiest would be to show that the dot product of V with another four-vector, e.g. the four-gradient, is Lorentz invariant, i.e. to show that... 

These usually consist of a non-magnetic casing, a rotor, and an electromagnetic pickup. The rotor is either a propeller or turbine freely suspended on ball bearings in the path of the flowing fluid with the axis of rotation in line with the flow. The rotor turns in the fluid flow stream at a rate proportional to the flow rate. As the rotor turns it cuts through the lines of force of an electric field produced by an adjacent induction coil. The electrical pulse output from the induction coil pickup is amplified and fed to readout instruments or recorders to give either total flow or flow rate [Holland and Chapman (1966)]. 

Mechanically operated screens are vibrated by means of an electromagnetic device as shown in Figure 1.40, or mechanically as shown in Figure 1.41. In the former case the screen itself is vibrated, and in the latter, the whole assembly. Because very rapid accelerations and retardations are produced, the power consumption and the wear on the bearings are high. These screens are sometimes mounted in a multi-deck fashion with... 

The laws of sound propagation in different media include the concept of ether, which is the hypothetical bearing substance of fight and electromagnetic waves. 

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