The next is a sample application used to illustrate the regular process for picking 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 has 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 having a 7/8 inch keyway as well as compressor includes a 92mm shaft having a 25mm keyway. The shaft separation is approximately seven inches between shaft ends with some skill to adjust the motor spot. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The first stage is always to ascertain what coupling kind will be to be picked for this application. Because the SU Style coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent alternative might be to look at an SX or DI Style coupling. The six bolt SX Style will accommodate both parallel misalignment along with the defined shaft separation. The dimension are going to be established by the choice torque as well as the shaft diameters.
Stage two: Subsequent, calculate the application torque and apply the service component to calculate the selection torque.The formula employed to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside the numbers in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Component = Variety Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Phase 3: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, greater than adequate to deal with the assortment torque calculated in stage two. The SX202-6, having said that, won’t support the 92mm shaft size. The next bigger dimension coupling, the SX228-6, will support the 92mm shaft size as well as the shaft separation dimension (BSE) is six.88 inches, quite close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may well appear to be extreme, nevertheless, the coupling dimension is necessary to take care of the bore dimension.
Stage 4: The SX228-6 coupling is rated for any greatest unbalanced pace of three,400 RPM, more than enough to help the application pace of one,150 RPM.
Phase five: To find out when the coupling will deal with the parallel misalignment, make use of the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance involving disc packs or ??S?¡¥ dimension from your table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for your application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It truly is constantly recommended to try and set up the coupling at approximately 20% of your allowable misalignment. For this coupling the installer need to endeavor to attain much better than 0.020 parallel misalignment with the time of installation. This will let for the more misalignment which will take place as the end result of products settle and basic equipment dress in.