The next is often a sample application utilized to illustrate the normal procedure for picking out 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 features a compressor application using a 225 horsepower electric motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft having a 7/8 inch keyway along with the compressor features a 92mm shaft with a 25mm keyway. The shaft separation is roughly seven inches involving shaft ends with some skill to change the motor location. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The very first step will be to ascertain what coupling sort should be to be picked for this application. Since the SU Style coupling only supports
just one flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent decision can be to look at an SX or DI Sort coupling. The 6 bolt SX Type will accommodate both parallel misalignment and also the defined shaft separation. The dimension might be established from the selection torque as well as the shaft diameters.
Step two: Up coming, determine the application torque and apply the support element to determine the assortment 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 from the numbers from the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Support Component = Selection Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Phase 3: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, a lot more than adequate to take care of the variety torque calculated in step two. The SX202-6, having said that, will not help the 92mm shaft size. The following more substantial dimension coupling, the SX228-6, will support the 92mm shaft size along with the shaft separation dimension (BSE) is six.88 inches, very close to the application?¡¥s sought after seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be excessive, on the other hand, the coupling dimension is important to manage the bore dimension.
Stage four: The SX228-6 coupling is rated for any maximum unbalanced pace of three,400 RPM, in excess of adequate to help the application pace of 1,150 RPM.
Stage 5: To determine should the coupling will manage the parallel misalignment, use the trig perform of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension through the table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It is often recommended to make an effort to set up the coupling at roughly 20% with the 
allowable misalignment. For this coupling the installer really should try and achieve improved than 0.020 parallel misalignment in the time of installation. This may permit for your added misalignment that should come about as the outcome of tools settle and standard tools wear.
