January 26, 2021

The following is actually a sample application utilised to illustrate the typical course of action for picking out a Disc coupling. Any resemblance to any current 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 electrical motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft by using a 7/8 inch keyway along with the compressor features a 92mm shaft having a 25mm keyway. The shaft separation is roughly seven inches concerning shaft ends with some capacity to modify the motor area. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage one: The initial step is to establish what coupling sort should be to be chosen for this application. Since the SU Form coupling only supports
just one flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The following selection could be to seem at an SX or DI Type coupling. The 6 bolt SX Form will accommodate both parallel misalignment plus the defined shaft separation. The size is going to be established from the variety torque as well as the shaft diameters.
Phase two: Next, determine the application torque and apply the service factor to calculate the choice 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 in 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 Element = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Make use of the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, in excess of ample to take care of the assortment torque calculated in stage two. The SX202-6, even so, will not help the 92mm shaft size. The subsequent more substantial dimension coupling, the SX228-6, will help the 92mm shaft size plus the shaft separation dimension (BSE) is 6.88 inches, very near to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps appear to be excessive, nevertheless, the coupling dimension is important to manage the bore size.
Phase 4: The SX228-6 coupling is rated to get a greatest unbalanced pace of three,400 RPM, over adequate to support the application velocity of one,150 RPM.
Phase 5: To determine in case the coupling will take care of the parallel misalignment, make use of the trig perform of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance involving 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 five.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It truly is normally advised to endeavor to set up the coupling at roughly 20% of the allowable misalignment. For this coupling the installer ought to attempt to achieve much better than 0.020 parallel misalignment with the time of set up. This will likely enable for that more misalignment that will occur as the result of tools settle and standard tools put on.