The following can be a sample application utilised to illustrate the typical procedure for selecting a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company features a compressor application working with a 225 horsepower electrical motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft using a 7/8 inch keyway and the compressor has a 92mm shaft using a 25mm keyway. The shaft separation is approximately 7 inches between shaft ends with some capacity to modify the motor place. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Step one: The primary stage would be to establish what coupling sort would be to be chosen for this application. Because the SU Sort coupling only supports
a single flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The next decision can be to look at an SX or DI Variety coupling. The six bolt SX Variety will accommodate both parallel misalignment as well as the defined shaft separation. The dimension will likely be determined by the variety torque as well as the shaft diameters.
Phase two: Upcoming, determine the application torque and apply the support factor to calculate the choice torque.The formula made use of 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 = 12,331 in-lbs
Application Torque x Support Factor = Variety Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Utilize the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, over adequate to deal with the choice torque calculated in stage two. The SX202-6, nonetheless, will not assistance the 92mm shaft dimension. The following bigger dimension coupling, the SX228-6, will assistance the 92mm shaft size plus the shaft separation dimension (BSE) is six.88 inches, quite near to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may well seem to be extreme, on the other hand, the coupling size is necessary to manage the bore size.
Stage four: The SX228-6 coupling is rated for a highest unbalanced pace of 3,400 RPM, in excess of adequate to assistance the application pace of one,150 RPM.
Phase 5: To find out if the coupling will deal with the parallel misalignment, use the trig function of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension from the table on web page 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), thus this coupling can accommodate the parallel misalignment.
Note: It is often advised to try to set up the coupling at approximately 20% of your allowable misalignment. For this coupling the installer should really seek to realize greater than 0.020 parallel misalignment on the time of installation. This can enable for that supplemental misalignment that should come about as the end result of gear settle and general products dress in.