The following is usually a sample application utilised to illustrate the regular procedure 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 utilizing a 225 horsepower electric motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft using a 7/8 inch keyway and the compressor features a 92mm shaft with a 25mm keyway. The shaft separation is roughly seven inches in between shaft ends with some capacity to modify the motor area. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Stage one: The 1st phase should be to figure out what coupling variety should be to be picked for this application. Because the SU Sort coupling only supports
a single flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent decision might be to look at an SX or DI Type coupling. The six bolt SX Variety will accommodate the two parallel misalignment plus the defined shaft separation. The dimension might be determined from the variety torque and the shaft diameters.
Stage 2: Following, determine the application torque and apply the support issue to calculate the choice 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 while 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 Services Issue = Assortment Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Use the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, greater than ample to handle the variety torque calculated in step two. The SX202-6, however, won’t help the 92mm shaft dimension. The next greater size coupling, the SX228-6, will help the 92mm shaft size and the shaft separation dimension (BSE) is 6.88 inches, 
extremely near to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may seem to be extreme, even so, the coupling size is necessary to take care of the bore dimension.
Step 4: The SX228-6 coupling is rated for a greatest unbalanced velocity of three,400 RPM, a lot more than ample to assistance the application velocity of one,150 RPM.
Step five: To find out should the coupling will take care of the parallel misalignment, utilize the trig perform of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension in the table on webpage D-13, or five.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), hence this coupling can accommodate the parallel misalignment.
Note: It’s normally proposed to try and set up the coupling at roughly 20% from the allowable misalignment. For this coupling the installer need to try to accomplish better than 0.020 parallel misalignment on the time of set up. This will make it possible for for that more misalignment that will come about because the result of gear settle and common gear put on.
