Ways In Choosing A Disc Coupling

The next is usually a sample application utilised to illustrate the standard system for deciding on 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 employing a 225 horsepower electric motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft that has a 7/8 inch keyway as well as the compressor features a 92mm shaft with 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.
Stage 1: The initial stage should be to figure out what coupling kind is always to be picked 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 decision will be to appear at an SX or DI Style coupling. The 6 bolt SX Type will accommodate both parallel misalignment and the defined shaft separation. The dimension might be established from the variety torque along with the shaft diameters.
Phase 2: Next, determine the application torque and apply the services issue to determine the selection torque.The formula made use of to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside 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 Element = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, a lot more than enough to take care of the assortment torque calculated in stage two. The SX202-6, however, is not going to support the 92mm shaft size. The subsequent larger dimension coupling, the SX228-6, will assistance the 92mm shaft size along with the shaft separation dimension (BSE) is six.88 inches, extremely near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may appear to be excessive, even so, the coupling size is critical to manage the bore dimension.
Stage 4: The SX228-6 coupling is rated to get a optimum unbalanced pace of 3,400 RPM, in excess of enough to support the application velocity of one,150 RPM.
Phase 5: To determine in the event the coupling will handle the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension in 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 utmost offset for your application is 1/32 inches (0.031), therefore this coupling can accommodate the parallel misalignment.
Note: It really is normally proposed to make an effort to set up the coupling at approximately 20% in the allowable misalignment. For this coupling the installer really should make an effort to realize much better than 0.020 parallel misalignment on the time of installation. This may permit to the extra misalignment that could take place because the end result of tools settle and standard equipment put on.