The next is usually a sample application utilized to illustrate the normal procedure for deciding on 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 includes a compressor application making use of a 225 horsepower electrical motor working at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft that has a 7/8 inch keyway plus the compressor features a 92mm shaft with a 25mm keyway. The shaft separation is approximately 7 inches in between shaft ends with some skill to alter the motor location. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Phase 1: The primary phase is usually to establish what coupling type would be to be chosen for this application. Because the SU Sort coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice can be to search at an SX or DI Variety coupling. The six bolt SX Style will accommodate each parallel misalignment and the defined shaft separation. The size will likely be determined from the assortment torque as well as shaft diameters.
Step 2: Up coming, determine the application torque and apply the services factor to calculate the selection torque.The formula utilized to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from 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 Service Factor = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase three: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, in excess of enough to handle the assortment torque calculated in stage two. The SX202-6, even so, will not support the 92mm shaft dimension. The next larger dimension coupling, the SX228-6, will support the 92mm shaft size and the shaft separation dimension (BSE) is 6.88 inches, pretty near to the 
application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may well seem to be extreme, however, the coupling dimension is important to deal with the bore size.
Step four: The SX228-6 coupling is rated for a maximum unbalanced velocity of 3,400 RPM, over adequate to assistance the application velocity of one,150 RPM.
Step five: To find out if your coupling will take care of the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension through the table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for your application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It really is always proposed to try to set up the coupling at approximately 20% of your allowable misalignment. For this coupling the installer ought to attempt to accomplish much better than 0.020 parallel misalignment on the time of set up. This will likely enable for the extra misalignment that may occur as the end result of tools settle and general gear wear.
