The next is really a sample application applied to illustrate the regular method for choosing a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization features a compressor application employing a 225 horsepower electrical motor working at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft that has a 7/8 inch keyway as well as compressor features a 92mm shaft having a 25mm keyway. The shaft separation is approximately seven inches among shaft ends with some potential to change the motor location. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The initial stage would be to decide what coupling sort will be to be selected for this application. Since the SU Variety coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The next alternative could be to seem at an SX or DI Style coupling. The six bolt SX Kind will accommodate the two parallel misalignment along with the defined shaft separation. The size is going to be established from the choice torque and also the shaft diameters.
Step two: Upcoming, calculate the application torque and apply the support factor to determine 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 while in the numbers in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Support Issue = Selection Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, in excess of enough to handle the variety torque calculated in step two. The SX202-6, however, 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 six.88 inches, quite close to the application?¡¥s wanted 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly seem to be extreme, on the other hand, the coupling dimension is critical to handle the bore dimension.
Step four: The SX228-6 coupling is rated for any highest unbalanced speed of three,400 RPM, a lot more than ample to support the application velocity of one,150 RPM.
Stage 5: To find out when the coupling will deal with the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension from the table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for that application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It can be usually advised to attempt to set up the coupling at approximately 20% of your allowable misalignment. For this coupling the installer ought to attempt to obtain superior than 0.020 parallel misalignment on the time of installation. This may make it possible for for the added misalignment that can happen since the result of equipment settle and general equipment dress in.