The next is really a sample application employed to illustrate the regular 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 working with a 225 horsepower electrical motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft using a 7/8 inch keyway and also the compressor includes a 92mm shaft which has a 25mm keyway. The shaft separation is approximately seven inches concerning shaft ends with some ability to change the motor area. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The very first stage is usually to determine what coupling sort is always to be chosen for this application. Because the SU Form coupling only supports
just one flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following option might be to search at an SX or DI Variety coupling. The 6 bolt SX Variety will accommodate each parallel misalignment as well as defined shaft separation. The dimension is going to be established by the choice torque plus the shaft diameters.
Phase 2: Following, 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 through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Issue = Selection Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Step three: Utilize the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, greater than adequate to manage the selection torque calculated in step two. The SX202-6, having said that, will not assistance the 92mm shaft size. The subsequent more substantial dimension coupling, the SX228-6, will help the 92mm shaft dimension along with the shaft separation dimension (BSE) is six.88 inches, pretty close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps appear to be extreme, even so, the coupling size is important to deal with the bore size.
Phase four: The SX228-6 coupling is rated for a greatest unbalanced velocity of three,400 RPM, more than ample to help the application pace of one,150 RPM.
Step 5: To find out if the coupling will deal with the parallel misalignment, use the trig perform of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension through the table on webpage D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It really is often advisable to seek to set up the coupling at roughly 20% in the allowable misalignment. For this coupling the installer need to try to obtain much better than 0.020 parallel misalignment on the time of installation. This may let for that added misalignment which will occur as the result of equipment settle and standard tools dress in.