The next is usually a sample application applied to illustrate the typical procedure for deciding on a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company has a compressor application employing a 225 horsepower electric motor operating at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft with a 7/8 inch keyway along with the compressor has a 92mm shaft using a 25mm keyway. The shaft separation is approximately seven inches among shaft ends with some capacity to adjust the motor place. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The very first step would be to decide what coupling form should be to be selected for this application. Because the SU Style coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next option would be to search at an SX or DI Style coupling. The six bolt SX Sort will accommodate both parallel misalignment and also the defined shaft separation. The dimension will be determined from the choice torque and the shaft diameters.
Stage two: Upcoming, calculate the application torque and apply the services issue to calculate the variety 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 your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Factor = Variety Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage three: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, more than sufficient to manage the variety torque calculated in phase 2. The SX202-6, however, is not going to help the 92mm shaft size. The following more substantial size coupling, the SX228-6, will help the 92mm shaft size and also the shaft separation dimension (BSE) is 6.88 inches, extremely close to the application?¡¥s desired 7 inch separation. The 
SX228-6 is rated at 62,000 in-lbs which could appear to be excessive, nevertheless, the coupling dimension is necessary to deal with the bore size.
Phase 4: The SX228-6 coupling is rated for any greatest unbalanced pace of 3,400 RPM, a lot more than sufficient to support the application pace of one,150 RPM.
Stage 5: To determine if the coupling will manage the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension from the table on web page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), for that reason this coupling can accommodate the parallel misalignment.
Note: It truly is normally advisable to seek to set up the coupling at approximately 20% of the allowable misalignment. For this coupling the installer must make an effort to reach improved than 0.020 parallel misalignment at the time of set up. This will let for the more misalignment that could occur as the result of tools settle and basic tools put on.
