The following is often a sample application applied to illustrate the standard course of action for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization includes a compressor application employing a 225 horsepower electric motor working at 1,150 RPM 
to drive a three cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft that has a 7/8 inch keyway along with the compressor features a 92mm shaft with a 25mm keyway. The shaft separation is approximately seven inches involving shaft ends with some ability to adjust the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The very first phase should be to decide what coupling type would be to be picked for this application. Because the SU Kind coupling only supports
a single flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next selection will be to appear at an SX or DI Style coupling. The 6 bolt SX Type will accommodate both parallel misalignment and also the defined shaft separation. The dimension might be established from the assortment torque plus the shaft diameters.
Step 2: Next, calculate the application torque and apply the services issue to determine the choice torque.The formula made use of to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside 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 Services Aspect = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over enough to manage the assortment torque calculated in stage two. The SX202-6, nevertheless, will not assistance the 92mm shaft size. The following larger size coupling, the SX228-6, will assistance the 92mm shaft size plus the shaft separation dimension (BSE) is 6.88 inches, extremely close to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may seem to be extreme, even so, the coupling size is critical to manage the bore dimension.
Phase 4: The SX228-6 coupling is rated for a maximum unbalanced speed of 3,400 RPM, in excess of enough to support the application pace of 1,150 RPM.
Step 5: To determine when the coupling will handle the parallel misalignment, make use of the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension from 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), consequently this coupling can accommodate the parallel misalignment.
Note: It’s always recommended to try and set up the coupling at approximately 20% in the allowable misalignment. For this coupling the installer should really make an effort to reach much better than 0.020 parallel misalignment on the time of installation. This will allow for your further misalignment that should take place since the consequence of products settle and standard gear put on.
