Bearings gearboxes

In order to keep this section to manageable proportions only the simplest cases are referred to. Multiple impellers, multiple bearing gearboxes and hollow shafts are not covered although the reader should remember that these will all make major contributions to the final analysis. 

Lubrication systems provide a constant source of clean oil to pump and compressor bearings, gearboxes, steam turbines, and rotating or moving equipment. A typical lubrication system includes a lubricant reservoir, pump, valves, heat exchanger, and piping. Figure 9-5 illustrates how an industrial lubrication system operates. 

Assemblies of small disks are rotated in a planetary movement around a central screw conveyor. The disks are mounted on six hoUow axles and the axles revolve on overhanging bearings from the gearbox at one end of the vessel where they are driven, via a drive shaft, by an electric motor. The filtrate is collected from the disks via the hoUow shafts and a filter valve into a large collecting pipe. The hoUow shafts also collect the water and air from the dewatering process, in another part of the rotational cycle. The number of disks mounted on the shafts can be adjusted for different materials, depending on the required capacity and the cake thickness to be used. 

Phosphor-bronze 88% Cu - H%Sn- 1% P High-load bearings for gearboxes, rolling mills, gudgeon pin bushes, etc., often used with overlay of softer material... 

Often, two or more types of sensors may be used in conjunction with each other to give more visibility to what is going on. Monitoring of a turbine generator is a good example. Information may be collected about shaft thrust, eccentricity, rpm, bearing wear, gearbox wear, and othens for maintenance and protection analysis. 

The turbogenerator speed must be maintained within narrow limits if it is to generate power acceptably and the control system must be capable of preventing over-speed upon sudden loss of load. For this latter requirement, fastacting valves are necessary with full modulation within 0.5 s. The security of the turbine is also dependent upon the lubrication of its bearings, and it will be found that the control systems are closely linked with the various lubricating systems (turbine, gearbox and alternator). 

A variety of bearing types is used in gearboxes. Narrowband windows should be established to monitor the rotational and defect frequencies generated by the specific type of bearing used in each application. 

Machine components The EIS should provide information on all components (e.g., bearings, gears, gearboxes, electric motors, pumps, etc.) that make up the machine-train. Since these components generate vibration energy and unique frequency components, this information is essential for proper analysis. At a minimum, the information sheet must include detailed bearing information, passing frequencies, and nameplate data. 

With the exception of helical gears, most gear sets should not generate axial or thrust loads in normal operation. However, at least one axial (Z-axis) measurement point should be placed on each of the gear shafts. The axial point should be located at the fixed, or thrust, bearing cap and oriented toward the gearbox. 

Inclusion of thermography into a predictive maintenance program will enable you to monitor the thermal efficiency of critical process systems that rely on heat transfer or retention electrical equipment and other parameters that will improve both the reliability and efficiency of plant systems. Infrared techniques can be used to detect problems in a variety of plant systems and equipment, including electrical switchgear, gearboxes, electrical substations, transmissions, circuit breaker panels, motors, building envelopes, bearings, steam lines, and process systems that rely on heat retention or transfer. 

With oil diagnostic systems it is also possible to recognize defects inside the gearbox. On the other hand, bearing damage, for example, cannot be accurately located. Regular oil diagnosis is also recommended to maximize oil life. 

Contamination in lubrication systems for bearings in industrial gearboxes. SKF Ball Bearing Journal, 1993, 242. 

The tail rotor gearbox is critical to directional control and stability but carries only about 5% of the total power. It may be lubricated with the same oil as the main gearbox but, because the bearings and gears are relatively small with low linear sliding speeds, they may be grease lubricated. 

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