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January 26, 2021

The next is a sample application utilized to illustrate the common course of action for picking a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company has a compressor application utilizing a 225 horsepower electrical motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft having a 7/8 inch keyway and the compressor has a 92mm shaft which has a 25mm keyway. The shaft separation is roughly 7 inches amongst shaft ends with some potential to adjust the motor location. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The initial step is to identify what coupling style is always to be chosen for this application. Because the SU Sort coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent option will be to look at an SX or DI Type coupling. The 6 bolt SX Sort will accommodate both parallel misalignment plus the defined shaft separation. The size is going to be established through the assortment torque and also the shaft diameters.
Step two: Following, determine the application torque and apply the service component to determine the assortment torque.The formula employed to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging during the numbers from the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Services Element = Choice Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, more than sufficient to deal with the choice torque calculated in step two. The SX202-6, nonetheless, is not going to assistance the 92mm shaft dimension. The next greater dimension coupling, the SX228-6, will assistance the 92mm shaft dimension plus the shaft separation dimension (BSE) is 6.88 inches, really close to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps seem to be excessive, however, the coupling size is necessary to handle the bore dimension.
Stage 4: The SX228-6 coupling is rated for a highest unbalanced pace of 3,400 RPM, over ample to support the application velocity of 1,150 RPM.
Step five: To find out if the coupling will handle the parallel misalignment, make use of the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension through the table on 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), thus this coupling can accommodate the parallel misalignment.
Note: It can be generally advisable to make an effort to set up the coupling at roughly 20% in the allowable misalignment. For this coupling the installer must try and realize superior than 0.020 parallel misalignment on the time of installation. This may permit for that added misalignment that may occur because the end result of products settle and general tools dress in.