Gear box

Upon satisfactory deterrnination of nontoxicity of a lubricant, the USDA issues one of two ratings HI for use where there is incidental or possible food contact as by splashing or dripping from machinery above an edible product, or H2 for no food contact as in sealed gear boxes or machinery below a product line (82—84). These classes include a number of petroleum and synthetic oils and greases. 

Example 2 Vibration Consider an electric motor rotating at 1800 rpm driving an 8-vane centrifugal pump rotating at 600 rpm. For this 3 1 speed reduction, assume a gear box having two gears of 100 and 300 tooth. Since 60 Hz is 1 rpm,... 

Main hub Main shaft Main shaft brake (J) Gear mechanism Gear box Brake disc (T) Coupling (i) Generator Frame... 

Cost iron engine block gear box rear axle... 

Figure 4-36. A single integral gear box connects one or more expanders to several compressor stages. (Source GHH-Borsig.)...

The maintenanee staff at the plant ehanged the high-speed pinion bearings in the train s gear box, but only as part of preventive maintenanee and as a preeautionary measure. Otherwise, maehinery availability has been high. 

The radial transducers should be placed within three inches of the bearing, and there should be two radial transducers at each bearing. Care should be taken not to place the probe at the nodal points. The two probes should be mounted 90° apart ( 5°) at a 45° ( 5°) angle from each side of the vertical center. Viewed from the drive end of the machine train, the x probe will be on the right side of the vertical, and the i probe will be on the left side of the vertical. Figures 4-10 and 4-11 show protection systems for a turbine and a gear box respectively. 

When exeessive vibration is deteeted in the gear box of a eompressor train (Figure 21-14) and is transferred to the platform below, a dampening effeet ean be ereated by inereasing the rigidity of the support below. This effeet ean be aeeomplished by first filling the platform eavity and then the gear-box support with epoxy mortar. 

Another common type of compressor is manufactured in an integrally geared configuration. It is basically an overhung style machine mounted on a gear box and uses the gear pinion shaft extension to mount an... 

Lubrication of cuuplitigs, Lubrication pumps. uid drivers, 309 Lubrication systems check valves, I commissioning, 462, 4ti coolers, 315 degassing drum, 322 filters, 316 gear box, 328 oil flooded helical, 109 overall system review, 1 overhead tanks, 319 piping, 322 pressure control valves, 313... 

TEFC - Totally Enclosed Fan Cooled where the shaft extends from both ends with a cooling fan attached to one with a shroud that directs air over strategically located cooling fins. This motor is m.ore commonly used when the motor is outside the air stream as when driving a gear box with a drive shaft or on blow-through towers. 

Pony motors are additional, small motors connected to the same fan shaft. They are typically about 1/4 the size of the full size motor. Pony motors do not lend themselves to gear box applications and are, therefore, primarily applied to belt drive applications. The big motor operates when full capacity is required and the small motor simply free wheels. At reduced capacity, the small motor operates and the big motor spins freely. 

Gear boxes are used on just about all large field erected cooling towers and many factory assembled towers- all of the propeller ty e fan, draw-through type. Almost all are right angle gear drives with the input shaft horizontal and the output... 

Variable speed control Speed change may be achieved by belts, pulleys, gear box sliding couplings, or a variable-speed motor. 

High-speed units are normally separable. That is, the compressor frame and driver are separated by a coupling or gear box. This is opposed to an integral unit where power cylinders are mounted on the same frame as the compressor cylinders, and the power pistons are attached to the same drive shaft as the compressor cylinders. 

Use nonlubricated compressors. However, oil is still needed for bearings and gear boxes and may leak into the compressors unless special attention is paid to their design and maintenance [19]. 

The difference between the brake horsepower and the water or liquid horsepower is the pump efficiency. The requirement in either case is the horsepower input to the shaft of the pump. For that reason, the brake horsepower represents the power required by the pump, which must be transmitted from the driver through the drive shaft through any coupling, gear-box, and/or belt drive mechanism to ultimately reach the driven shaft of the pump. Therefore, the losses in transmission from the driver to the pump itself must be added to the input requirement of the driven pump and are not included in the pump s brake horsepower requirement. 

The driver horsepower must be greater than the calculated (or value read from curves) input BHP to the shaft of the pump. The mechanical losses in the coupling, V-belt, gear-box, or other drive plus the losses in the driver must be accounted for in order that the driver rated power output will be sufficient to handle the pump. 

When the actual maximum gear box horsepower is known from the manufacturer, it should be used as long as it is equal to or greater than the 5% allowance noted above. The impeller/fluid horsepower allowable variation should still be 10% or greater. For example, if the calculated required motor drive (or turbine drive) hp = 23, (i.e., 19.55/0.85), the next standard motor is 25 hp, so use this, never less than the 23 indicated above because 23 hp is non-standard, and no such motor hp exists. 

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