January 26, 2021

The following is a sample application used to illustrate the standard procedure for picking out 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:
An organization has a compressor application working with a 225 horsepower electric motor running 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 has a 92mm shaft with a 25mm keyway. The shaft separation is roughly 7 inches between shaft ends with some capacity to alter the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase 1: The primary phase is to ascertain what coupling type should be to be picked for this application. Since the SU Kind coupling only supports
a single flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following selection can be to look at an SX or DI Form coupling. The six bolt SX Form will accommodate the two parallel misalignment and the defined shaft separation. The size might be established through the selection torque and the shaft diameters.
Stage two: Subsequent, determine the application torque and apply the support component to determine the choice torque.The formula employed to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside 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 Aspect = Assortment Torque
12,331 in-lbs x 3.0 = 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, more than ample to manage the choice torque calculated in stage two. The SX202-6, nevertheless, won’t assistance the 92mm shaft dimension. The next greater size coupling, the SX228-6, will support the 92mm shaft dimension as well as shaft separation dimension (BSE) is six.88 inches, really close to the application?¡¥s preferred 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be excessive, nonetheless, the coupling size is important to manage the bore size.
Stage four: The SX228-6 coupling is rated for any greatest unbalanced velocity of 3,400 RPM, a lot more than enough to help the application velocity of 1,150 RPM.
Step five: To find out in case the coupling will take care of the parallel misalignment, use the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance involving disc packs or ??S?¡¥ dimension through the table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset to the application is 1/32 inches (0.031), therefore this coupling can accommodate the parallel misalignment.
Note: It really is often encouraged to endeavor to set up the coupling at approximately 20% of the allowable misalignment. For this coupling the installer must attempt to reach greater than 0.020 parallel misalignment on the time of installation. This can let for that supplemental misalignment that may come about as the outcome of products settle and general gear dress in.