Gearboxes

The gearbox is a major component of the rotating assembly, which creates the differential speed between the bowl and the conveyor. 

There are two main types of gearboxes used on decanters. These are the epicyclic gearbox and the Cyclo gearbox, made by Sumitomo of Japan. However there are a number of decanters which have eliminated the gearbox by using a hydraulic system called a Rotodiff manufactured by the Swiss company Viscotherm. The Rotodiff and the Cyclo gearbox will be covered in more detail in Sections 2.3.7 and 2.4.15, respectively. 

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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. 

In many large plants, an intermediate pressure (IP) turbine is located on the same shaft as either the HP turbine or the low pressure (LP) turbine. In this arrangement, a common gearbox translates the torque from the high speed turbine shaft to a generator shaft turning at a much lower speed. Unless reheat is used, the steam exiting the HP turbine is typicaHy used directly in the IP turbine. 

Fig. 1. A trough for deposition of monolayers on soHd substrates A, bath B, a moving barrier C, a motor D, a pressure-control device E, a surface pressure balance F, a motor with a gearbox that lowers and raises the substrate and G, a soHd substrate. The film material (S) has a hydrophobic tail and...

FIG. 18-50 Intermeshing corotating twin screw extruder (a) drive motor, (h) gearbox, (c) feed port, (d) barrel, (e) assembled rotors, (f) vent, (g) barrel valve, (h) kneading paddles, ( ) conveying screws, (/) splined shafts, (k) blister rings, (APV Chemical Machinery, Inc.)... 

This can be checked with the help of a phase sequence indicator. This is a simple instrument that houses a small 30 motor, which rotates a pointer connected to the motor through a gearbox. The direction of rotation of the pointer will determine the phase. sequence of the system. 

Lead-bronze 75% Cu - 20% Pb - 5% Sn High performance i.c. engines, camshafts, gearboxes... 

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... 

Fig. 28.1. Schematic of a typical conveyor system. Because the belt tends to sag between the support rollers it must be kept under a constant tension T. This is done by hanging a large weight on the tension drum. The drive is supplied by coupling a large electric motor to the shaft of the drive drum via a suitable gearbox and overload clutch.

Why do we use the word driver We tend to think that pumps are powered by r-r motors. However, some pumps are powered by internal combustion engines, or with turbines or hydraulic motors. Not always are pumps and drivers connected h a direct coupling. Some pumps are coupled through pulleys, chain drives, gearboxes or even transmissions. 

As mentioned earlier, a variety of turbomaehines are required to produee nitrie aeid. In the ease of small plants, these maehines represent a substantial investment. A eombination of proven air eompressor modules with newly developed expansion turbines and nitrous gas eompressors on a single gearbox provides a new, low-eost alternative and gives the plant owner/eontraetor useful potential for faeulty optimization (Figures 4-36 through 4-38). 

Figure 5-3. Overhung, gearbox mounted centrifugal compressor. Courtesy of Atlas Copco Comptec fnc.)...

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. 

It may be noted that in this area the newly introduced nylon 46 has become of interest in auto automatic gears, gearboxes, engine differentials and the clutch area because of its exceptional ability (for a polyamide) to withstand severe mechanical and thermal loading. ... 

Figure 2.8 shows a reduetion gearbox being driven by a motor that develops a torque T tn(t). It has a gear reduetion ratio of and the moments of inertia on the motor and output shafts are and /q, and the respeetive damping eoeffieients Cm and Cq. Find the differential equation relating the motor torque CmfO and the output angular position 6a t). 

Fig. 2.9 Free-body diagrams for reduction gearbox. Gearbox parameters...

Gearbox, lead-screw and machine-table. With reference to Figure 2.9 (free-body diagram of a gearbox), the motor-shaft will have zero viscous friction Cm, hence equation (2.22), using Laplace notation, becomes... 

Propeller anemometer A device used for measuring airflow in which the air velocity revolves a propeller, the shaft of which is connected to a gearbox and measuring dial. 

Scheduled maintenance Work performed at a time specifically planned to minimize interruptions in machine availability e.g. changing a gearbox when machine is not required for use (includes predictive and preventive maintenance). 

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