The next is really a sample application employed to illustrate the typical procedure for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company features a compressor application using a 225 horsepower electric motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft using a 7/8 inch keyway along with the compressor features a 92mm shaft that has a 25mm keyway. The shaft separation is roughly 7 inches amongst shaft ends with some potential to alter the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase 1: The initial phase should be to ascertain what coupling sort would be to be selected for this application. Since the SU Sort coupling only supports
a single flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next decision would be to look at an SX or DI Sort coupling. The 6 bolt SX Kind will accommodate both parallel misalignment along with the defined shaft separation. The size might be established from the selection torque along with the shaft diameters.
Stage 2: Up coming, determine the application torque and apply the service aspect to calculate the selection torque.The formula utilised to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging in 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 Services Component = Choice Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Make use of the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, over ample to take care of the assortment torque calculated in step 2. The SX202-6, nonetheless, is not going to help the 92mm shaft size. The following larger dimension coupling, the SX228-6, will help the 92mm shaft dimension plus the shaft separation dimension (BSE) is 6.88 inches, extremely close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, nonetheless, the coupling size is critical to take care of the bore size.
Step 4: The SX228-6 coupling is rated to get a highest unbalanced pace of three,400 RPM, over enough to help the application velocity of 1,150 RPM.
Phase five: To find out if your coupling will 
take care of the parallel misalignment, make use of the trig perform 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 five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset for your application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It is actually constantly advisable to make an effort to set up the coupling at approximately 20% from the allowable misalignment. For this coupling the installer need to try to attain better than 0.020 parallel misalignment in the time of installation. This can allow for the further misalignment that may take place as the outcome of tools settle and general gear wear.
