Gear-tooth coupling

This led to the knowledge that extreme high-speed gears, which must be equipped with toothed couplings for lateral critical speed reasons, should have a single helical toothing that is not affected by additional external thrusts. 

Gear couplings have a pilot incorporated into the male tooth form to support the loose member of the coupling in a concentric manner at speed, as shown in Figure 18-4. 

API 617 recognizes the need for the compressor thrust design to take into account peripheral factors such as the coupling. Gear couplings can transmit thrust to the compressor because of tooth friction. The standard uses an arbitrary friction coefficient of, 25, which can be a design basis. Flexible element couplings transmit less thrust because of the lower flex ing element axial stiffness. 

Viscosity For a directly coupled turbine for power generation, a typical viscosity would be in the range of 32-46 cSt at 40°C (ISO 32-46 at 104°F). Geared units require a higher viscosity to withstand tooth loading typically within the range of 68-100 cSt at 40°C (ISO 68-100 at 104°F). 

If motor II is at rest, pulley 5 becomes stationary same with pulley 1 so that countershaft II counterrotates at uji as does countershaft I. This motion is similarly conveyed to the rotary arms of frame II by 1 1 gearing between gears 3 and 4, resulting in rotation of frame II at 2toi or the same angular velocity as that of the centerpiece. Consequently, coupling of pulleys 6 to 7 and 8 to 9 with toothed belts produces no additional motion to the rotary shaft, which simply revolves with frame II at 2o i around the central axis of the apparatus. 

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