The next is really a sample application employed to illustrate the normal approach for selecting a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization has a compressor application utilizing a 225 horsepower electrical motor working at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft with a 7/8 inch keyway and also the compressor includes a 92mm shaft with a 25mm keyway. The shaft separation is roughly seven inches between shaft ends with some ability to modify the motor location. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The primary stage would be to determine what coupling sort would be to be selected for this application. Since the SU Variety coupling only supports
a single flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference will be to search at an SX or DI Style coupling. The 6 bolt SX Form will accommodate each parallel misalignment as well as defined shaft separation. The size will likely be determined by the selection torque as well as the shaft diameters.
Stage two: Up coming, determine the application torque and apply the support issue to determine the choice torque.The formula utilized to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from 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 = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Utilize the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over sufficient to manage the selection torque calculated in step 2. The SX202-6, on the other hand, won’t support the 92mm shaft size. The following greater size coupling, the SX228-6, will help the 92mm shaft size as well as shaft separation dimension (BSE) is six.88 inches, quite close to the application?¡¥s sought after seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, even so, the coupling dimension is necessary to handle the bore dimension.
Phase 4: The SX228-6 coupling is rated to get a maximum unbalanced pace of 3,400 RPM, greater than ample to assistance 
the application pace of 1,150 RPM.
Phase five: To determine in case the coupling will take care of the parallel misalignment, use the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension from the table on page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for that application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It truly is normally suggested to attempt to set up the coupling at approximately 20% with the allowable misalignment. For this coupling the installer really should endeavor to reach greater than 0.020 parallel misalignment in the time of set up. This will permit for your more misalignment that could come about because the result of gear settle and common products put on.