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January 26, 2021

The following is usually a sample application made use of to illustrate the conventional approach for selecting 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 using a 225 horsepower electrical motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft using a 7/8 inch keyway and also the compressor has a 92mm shaft using a 25mm keyway. The shaft separation is approximately 7 inches in between shaft ends with some ability to alter the motor place. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Step one: The first phase should be to decide what coupling kind would be to be selected for this application. Since the SU Sort coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference can be to seem at an SX or DI Type coupling. The 6 bolt SX Form will accommodate the two parallel misalignment as well as defined shaft separation. The size will be established through the choice torque along with the shaft diameters.
Step two: Following, calculate the application torque and apply the services element to calculate the variety torque.The formula utilized to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Element = Choice Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Phase 3: Use the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over ample to deal with the choice torque calculated in phase two. The SX202-6, nevertheless, won’t support the 92mm shaft size. The following larger dimension coupling, the SX228-6, will assistance the 92mm shaft size along with the shaft separation dimension (BSE) is 6.88 inches, extremely near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, however, the coupling dimension is necessary to take care of the bore dimension.
Step 4: The SX228-6 coupling is rated to get a maximum unbalanced velocity of 3,400 RPM, over sufficient to help the application velocity of one,150 RPM.
Phase 5: To determine if the coupling will manage the parallel misalignment, utilize the trig perform of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension in the table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset to the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It is actually generally suggested to make an effort to install the coupling at roughly 20% with the allowable misalignment. For this coupling the installer really should try to obtain superior than 0.020 parallel misalignment at the time of set up. This can make it possible for for your further misalignment that should occur as the consequence of equipment settle and standard gear put on.