January 26, 2021

The next is actually a sample application applied to illustrate the standard procedure for picking 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:
A company includes a compressor application employing a 225 horsepower electrical motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft having a 7/8 inch keyway and also the compressor has a 92mm shaft having a 25mm keyway. The shaft separation is roughly seven inches between shaft ends with some capability to alter the motor location. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The first stage is to ascertain what coupling variety would be to be selected for this application. Since the SU Kind coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The following option could be to look at an SX or DI Type coupling. The six bolt SX Form will accommodate the two parallel misalignment as well as the defined shaft separation. The dimension will likely be established by the choice torque and also the shaft diameters.
Step 2: Up coming, calculate the application torque and apply the support element to determine the assortment 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 in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Support Component = Choice Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase three: Make use of the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, in excess of adequate to manage the variety torque calculated in stage two. The SX202-6, nevertheless, will not support the 92mm shaft dimension. The following larger size coupling, the SX228-6, will assistance the 92mm shaft dimension as well as the shaft separation dimension (BSE) is six.88 inches, really close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, nonetheless, the coupling dimension is important to manage the bore dimension.
Step 4: The SX228-6 coupling is rated to get a maximum unbalanced speed of three,400 RPM, more than adequate to support the application speed of one,150 RPM.
Stage five: To determine if your coupling will manage the parallel misalignment, use the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension in the table on web page D-13, or five.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), as a result this coupling can accommodate the parallel misalignment.
Note: It really is normally suggested to try and set up the coupling at roughly 20% from the allowable misalignment. For this coupling the installer should try and realize superior than 0.020 parallel misalignment with the time of set up. This can enable to the extra misalignment that can take place since the consequence of products settle and basic equipment put on.