The next can be a sample application used to illustrate the normal method 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:
An organization includes a compressor application utilizing a 225 horsepower electrical motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft with a 7/8 inch keyway along with the compressor features a 92mm shaft having a 25mm keyway. The shaft separation is approximately seven inches between shaft ends with some potential to modify the motor place. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The first stage is usually to ascertain what coupling variety is to be selected for this application. Since the SU Kind coupling only supports
a single 
flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice can be to seem at an SX or DI Style coupling. The 6 bolt SX Kind will accommodate each parallel misalignment and also the defined shaft separation. The dimension are going to be established from the selection torque and also the shaft diameters.
Stage 2: Subsequent, calculate the application torque and apply the services factor to calculate the assortment torque.The formula made use of 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 through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Support Aspect = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, a lot more than sufficient to manage the variety torque calculated in stage two. The SX202-6, however, won’t assistance the 92mm shaft dimension. The subsequent bigger size coupling, the SX228-6, will help the 92mm shaft dimension as well as the shaft separation dimension (BSE) is six.88 inches, pretty close to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which could seem to be excessive, nonetheless, the coupling size is necessary to deal with the bore dimension.
Step 4: The SX228-6 coupling is rated to get a optimum unbalanced pace of 3,400 RPM, a lot more than sufficient to help the application velocity of 1,150 RPM.
Step five: To determine when the coupling will manage the parallel misalignment, utilize the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance 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 five.50 = 0.096 inches. The maximum offset to the application is 1/32 inches (0.031), therefore this coupling can accommodate the parallel misalignment.
Note: It really is constantly advised to make an effort to install the coupling at approximately 20% on the allowable misalignment. For this coupling the installer should really endeavor to reach improved than 0.020 parallel misalignment with the time of installation. This may enable for that supplemental misalignment that will take place as the consequence of equipment settle and basic products wear.
