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January 26, 2021

The following is often a sample application used to illustrate the conventional approach for choosing a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company has 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 which has a 7/8 inch keyway as well as compressor features a 92mm shaft with a 25mm keyway. The shaft separation is roughly 7 inches in between shaft ends with some skill to adjust the motor place. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The initial phase will be to ascertain what coupling style would be to be chosen for this application. Because the SU Form coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next alternative might be to appear at an SX or DI Style coupling. The six bolt SX Type will accommodate the two parallel misalignment along with the defined shaft separation. The dimension might be established through the selection torque as well as the shaft diameters.
Stage 2: Subsequent, calculate the application torque and apply the services issue to determine the variety torque.The formula used to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Services Component = Variety Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Utilize the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, a lot more than ample to handle the variety torque calculated in step two. The SX202-6, however, won’t help the 92mm shaft dimension. The subsequent greater dimension coupling, the SX228-6, will assistance the 92mm shaft size plus the shaft separation dimension (BSE) is six.88 inches, very close to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps appear to be excessive, nevertheless, the coupling dimension is critical to handle the bore size.
Phase four: The SX228-6 coupling is rated for a optimum unbalanced speed of three,400 RPM, a lot more than adequate to help the application velocity of one,150 RPM.
Stage five: To determine in case the coupling will manage the parallel misalignment, utilize 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 from your 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 for the application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It can be normally recommended to endeavor to set up the coupling at approximately 20% on the allowable misalignment. For this coupling the installer should attempt to accomplish better than 0.020 parallel misalignment in the time of installation. This may make it possible for for the more misalignment that could arise as the consequence of gear settle and general gear put on.