January 26, 2021

The next is often a sample application utilised to illustrate the conventional course of action for picking a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization includes a compressor application making use of 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 by using a 7/8 inch keyway as well as the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is approximately seven inches amongst shaft ends with some means to change the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The initial stage will be to figure out what coupling kind is always to be chosen for this application. Because the SU Type coupling only supports
a single flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next selection could be to look at an SX or DI Form coupling. The six bolt SX Style will accommodate the two parallel misalignment and the defined shaft separation. The dimension is going to be established by the variety torque along with the shaft diameters.
Phase two: Upcoming, determine the application torque and apply the service issue to calculate the selection torque.The formula applied to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Aspect = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Make use of the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, a lot more than ample to manage the assortment torque calculated in step two. The SX202-6, having said that, is not going to support the 92mm shaft size. The following larger size coupling, the SX228-6, will assistance the 92mm shaft size as well as the shaft separation dimension (BSE) is six.88 inches, very near to the application?¡¥s preferred 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps appear to be excessive, nonetheless, the coupling size is critical to manage the bore dimension.
Stage 4: The SX228-6 coupling is rated for a optimum unbalanced speed of 3,400 RPM, a lot more than ample to support the application pace of one,150 RPM.
Phase 5: To determine when the coupling will handle the parallel misalignment, make use of the trig perform of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension from the table on web page D-13, or 5.50 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 really is generally encouraged to make an effort to set up the coupling at approximately 20% from the allowable misalignment. For this coupling the installer really should attempt to realize better than 0.020 parallel misalignment on the time of installation. This may allow to the extra misalignment that may happen because the end result of tools settle and standard equipment put on.