January 26, 2021

The next is often a sample application utilised to illustrate the standard method for choosing a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization has a compressor application employing a 225 horsepower electrical motor working at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft having a 7/8 inch keyway plus the compressor has a 92mm shaft having a 25mm keyway. The shaft separation is approximately 7 inches involving shaft ends with some capacity to alter the motor location. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage one: The 1st stage will be to figure out what coupling type is to be selected for this application. Because the SU Style coupling only supports
a single flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The next alternative will be to look at an SX or DI Kind coupling. The six bolt SX Kind will accommodate both parallel misalignment as well as the defined shaft separation. The size are going to be determined by the selection torque and the shaft diameters.
Stage two: Upcoming, calculate the application torque and apply the services issue to determine the selection torque.The formula used to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Component = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Use the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over adequate to handle the choice torque calculated in stage 2. The SX202-6, nonetheless, will not assistance the 92mm shaft dimension. The next more substantial size coupling, the SX228-6, will help the 92mm shaft size as well as shaft separation dimension (BSE) is 6.88 inches, very close to the application?¡¥s preferred 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be excessive, nevertheless, the coupling size is critical to take care of the bore dimension.
Stage 4: The SX228-6 coupling is rated for a maximum unbalanced pace of three,400 RPM, over enough to support the application speed of 1,150 RPM.
Step five: To find out if the coupling will deal with the parallel misalignment, utilize 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 through the table on web page D-13, or five.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 really is usually recommended to attempt to install the coupling at roughly 20% of the allowable misalignment. For this coupling the installer should really seek to accomplish greater than 0.020 parallel misalignment with the time of installation. This can permit for that additional misalignment that can occur as the consequence of gear settle and common tools put on.