Techniques In Deciding on A Disc Coupling

The next is usually a sample application utilised to illustrate the typical course of action for selecting 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:
A company features a compressor application working with a 225 horsepower electrical motor operating at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft with a 7/8 inch keyway as well as the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is roughly seven inches involving shaft ends with some capability to alter the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Step one: The 1st stage should be to figure out what coupling type is always to be chosen for this application. Because the SU Kind coupling only supports
just one flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The following alternative would be to appear at an SX or DI Form coupling. The 6 bolt SX Variety will accommodate both parallel misalignment and the defined shaft separation. The dimension is going to be determined from the variety torque as well as shaft diameters.
Phase 2: Up coming, calculate the application torque and apply the services element to determine the selection torque.The formula utilized 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 the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Services Element = Choice Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Phase three: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, greater than sufficient to manage the variety torque calculated in step two. The SX202-6, however, will not assistance the 92mm shaft dimension. The subsequent bigger dimension coupling, the SX228-6, will assistance the 92mm shaft dimension and also the shaft separation dimension (BSE) is six.88 inches, extremely near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, on the other hand, the coupling dimension is important to handle the bore size.
Stage four: The SX228-6 coupling is rated for any greatest unbalanced pace of 3,400 RPM, in excess of ample to assistance the application velocity of 1,150 RPM.
Step 5: To find out in case the coupling will manage the parallel misalignment, make use of the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension through the table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It is actually often recommended to seek to set up the coupling at roughly 20% with the allowable misalignment. For this coupling the installer need to make an effort to realize improved than 0.020 parallel misalignment on the time of set up. This may permit for that additional misalignment which will come about as the consequence of gear settle and basic products put on.