The following is actually a sample application used to illustrate the common procedure for picking 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:
An organization has a compressor application employing a 225 horsepower electric motor working at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft by using a 7/8 inch keyway as well as compressor has a 92mm shaft that has a 25mm keyway. The shaft separation is approximately 7 inches in between shaft ends with some skill to adjust the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The initial phase will be to ascertain what coupling variety should be to be picked for this application. Since the SU Form coupling only supports
a single flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next selection will be to seem at an SX or DI Kind coupling. The 6 bolt SX Sort will accommodate each parallel misalignment along with the defined shaft separation. The size will likely be established by the choice torque as well as the shaft diameters.
Step two: Upcoming, determine the application torque and apply the support factor to determine the variety torque.The formula applied to calculate 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 = twelve,331 in-lbs
Application Torque x Support Factor = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: 
Utilize the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, in excess of ample to handle the choice torque calculated in phase 2. The SX202-6, on the other hand, won’t support the 92mm shaft size. The following more substantial dimension coupling, the SX228-6, will help the 92mm shaft dimension plus the shaft separation dimension (BSE) is 6.88 inches, incredibly near to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be excessive, even so, the coupling size is necessary to manage the bore dimension.
Step four: The SX228-6 coupling is rated for a optimum unbalanced velocity of three,400 RPM, greater than sufficient to support the application pace of one,150 RPM.
Phase 5: To determine when the coupling will deal with the parallel misalignment, use the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance between 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), therefore this coupling can accommodate the parallel misalignment.
Note: It truly is normally encouraged to make an effort to install the coupling at roughly 20% on the allowable misalignment. For this coupling the installer should attempt to accomplish far better than 0.020 parallel misalignment at the time of installation. This will likely make it possible for for your added misalignment that could happen since the outcome of tools settle and general tools wear.
