January 26, 2021

The next can be a sample application utilized to illustrate the regular course of action for picking out a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company has a compressor application using a 225 horsepower electric motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft with a 7/8 inch keyway and also the compressor has a 92mm shaft having a 25mm keyway. The shaft separation is roughly seven inches between shaft ends with some potential to alter the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The very first stage would be to figure out what coupling style should be to be chosen for this application. Because the SU Style coupling only supports
a single flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The following preference could be to appear at an SX or DI Kind coupling. The 6 bolt SX Type will accommodate each parallel misalignment as well as the defined shaft separation. The dimension will likely be established through the variety torque as well as shaft diameters.
Step 2: Following, determine the application torque and apply the support aspect to calculate the variety 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 while in 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 Support Element = Choice Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 3: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, greater than enough to deal with the choice torque calculated in stage 2. The SX202-6, on the other hand, won’t help the 92mm shaft dimension. The following bigger dimension coupling, the SX228-6, will assistance the 92mm shaft size along with the shaft separation dimension (BSE) is six.88 inches, quite near to the application?¡¥s preferred 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be excessive, nonetheless, the coupling size is critical to handle the bore size.
Phase four: The SX228-6 coupling is rated to get a optimum unbalanced velocity of three,400 RPM, more than adequate to support the application speed of 1,150 RPM.
Step 5: To find out if the coupling will handle the parallel misalignment, use the trig function of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension from your table on webpage D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It can be generally proposed to try and install the coupling at approximately 20% of the allowable misalignment. For this coupling the installer must make an effort to realize superior than 0.020 parallel misalignment with the time of set up. This will enable for your supplemental misalignment that may arise as the end result of tools settle and standard equipment put on.