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January 26, 2021

The following is often a sample application utilized to illustrate the conventional procedure for picking out a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company has a compressor application applying a 225 horsepower electrical motor working at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft by using a 7/8 inch keyway and the compressor features a 92mm shaft using a 25mm keyway. The shaft separation is approximately seven inches involving shaft ends with some potential to adjust the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The first phase will be to identify what coupling kind should be to be picked for this application. Because the SU Kind coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The following alternative will be to seem at an SX or DI Variety coupling. The six bolt SX Type will accommodate the two parallel misalignment plus the defined shaft separation. The dimension will be established from the assortment torque and also the shaft diameters.
Stage 2: Up coming, determine the application torque and apply the support aspect to calculate the variety torque.The formula applied to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Issue = Variety Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, a lot more than ample to deal with the variety torque calculated in phase 2. The SX202-6, however, will not help the 92mm shaft size. The subsequent greater size coupling, the SX228-6, will help the 92mm shaft dimension as well as the shaft separation dimension (BSE) is six.88 inches, very close to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may appear to be extreme, nevertheless, the coupling dimension is critical to handle the bore dimension.
Step four: The SX228-6 coupling is rated for any optimum unbalanced velocity of 3,400 RPM, more than sufficient to support the application velocity of 1,150 RPM.
Stage 5: To determine in case the coupling will take care of the parallel misalignment, use the trig perform of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension through the table on web page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It truly is usually advised to make an effort to install the coupling at roughly 20% of your allowable misalignment. For this coupling the installer should attempt to realize better than 0.020 parallel misalignment at the time of installation. This may enable for your more misalignment that will come about because the outcome of gear settle and basic gear put on.