The following is actually a sample application utilised to illustrate the common method for picking out 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 features a compressor application making use of a 225 horsepower electrical motor operating at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft by using a 7/8 inch keyway as well as the compressor has a 92mm shaft by using a 25mm keyway. The shaft separation is roughly 7 inches amongst shaft ends with some capability to alter the motor place. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage one: The 
initial phase will be to figure out what coupling variety is to be selected for this application. Since the SU Kind coupling only supports
a single flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next choice could be to appear at an SX or DI Sort coupling. The six bolt SX Kind will accommodate each parallel misalignment as well as defined shaft separation. The size will probably be determined from the assortment torque as well as shaft diameters.
Phase two: Following, calculate the application torque and apply the services aspect to calculate the choice 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 during the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Services Aspect = Selection Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Step three: 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 manage the choice torque calculated in phase 2. The SX202-6, nevertheless, is not going to assistance the 92mm shaft dimension. The following greater size coupling, the SX228-6, will assistance the 92mm shaft dimension plus the shaft separation dimension (BSE) is 6.88 inches, very close to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be excessive, on the other hand, the coupling dimension is critical to handle the bore size.
Phase four: The SX228-6 coupling is rated for a optimum unbalanced velocity of 3,400 RPM, over adequate to assistance the application velocity of 1,150 RPM.
Step 5: To determine if your coupling will take care of 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 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), as a result this coupling can accommodate the parallel misalignment.
Note: It is always advised to try to install the coupling at roughly 20% from the allowable misalignment. For this coupling the installer should really attempt to realize superior than 0.020 parallel misalignment at the time of installation. This can allow to the additional misalignment that may come about because the consequence of equipment settle and general gear wear.
