Ways In Selecting A Disc Coupling

The following can be a sample application utilized to illustrate the normal system for choosing 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 utilizing a 225 horsepower electrical motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft that has a 7/8 inch keyway and the compressor includes a 92mm shaft with a 25mm keyway. The shaft separation is approximately 7 inches concerning shaft ends with some ability to alter the motor location. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step one: The 1st phase should be to identify what coupling sort is usually to be picked for this application. Since the SU Variety coupling only supports
a single flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference can be to look at an SX or DI Variety coupling. The 6 bolt SX Type will accommodate the two parallel misalignment plus the defined shaft separation. The size might be established by the selection torque plus the shaft diameters.
Phase 2: Up coming, determine the application torque and apply the service aspect to determine the choice torque.The formula made use of to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from 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 Support Issue = Selection Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Phase 3: Use the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, a lot more than enough to handle the selection torque calculated in stage two. The SX202-6, on the other hand, will not assistance the 92mm shaft dimension. The next bigger dimension coupling, the SX228-6, will assistance the 92mm shaft size as well as shaft separation dimension (BSE) is six.88 inches, pretty close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps seem to be extreme, on the other hand, the coupling size is important to take care of the bore dimension.
Step four: The SX228-6 coupling is rated to get a optimum unbalanced speed of three,400 RPM, greater than enough to help the application speed of 1,150 RPM.
Step five: To find out if your coupling will deal with 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 in 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 5.50 = 0.096 inches. The utmost offset for that application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It is constantly suggested to make an effort to set up the coupling at approximately 20% with the allowable misalignment. For this coupling the installer should try to accomplish greater than 0.020 parallel misalignment on the time of installation. This will likely permit to the extra misalignment that can arise since the end result of gear settle and general gear wear.


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