January 26, 2021

The next is actually a sample application made use of to illustrate the typical approach for picking out 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:
An organization features a compressor application applying a 225 horsepower electric motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft which has a 7/8 inch keyway and the compressor includes a 92mm shaft using a 25mm keyway. The shaft separation is approximately seven inches amongst shaft ends with some skill to adjust the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The initial stage will be to establish what coupling type would be to be selected for this application. Because the SU Variety coupling only supports
just one flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The following decision might be to seem at an SX or DI Sort coupling. The six bolt SX Kind will accommodate both parallel misalignment plus the defined shaft separation. The dimension will be established by the variety torque and the shaft diameters.
Stage two: Up coming, determine the application torque and apply the services component to determine the selection 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 in the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Services Issue = Assortment Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Stage three: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, in excess of enough to deal with the selection torque calculated in phase two. The SX202-6, on the other hand, is not going to help the 92mm shaft size. The following more substantial size coupling, the SX228-6, will assistance the 92mm shaft dimension as well as shaft separation dimension (BSE) is six.88 inches, incredibly near to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be extreme, even so, the coupling dimension is important to manage the bore dimension.
Step four: The SX228-6 coupling is rated for any highest unbalanced pace of 3,400 RPM, greater than sufficient to help the application pace of one,150 RPM.
Stage five: To determine if your coupling will manage the parallel misalignment, make use of the trig perform of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension from the table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.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’s often proposed to try and install the coupling at roughly 20% of the allowable misalignment. For this coupling the installer ought to try and realize greater than 0.020 parallel misalignment at the time of installation. This will make it possible for for the more misalignment that could come about because the consequence of tools settle and standard equipment wear.