The following is actually a sample application used to illustrate the common method for selecting a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company has a compressor application using a 225 horsepower electrical 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 having a 7/8 inch keyway as well as compressor has a 92mm shaft by using a 25mm keyway. The shaft separation is roughly 7 inches between shaft ends with some potential to modify the motor spot. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The first step is always to ascertain what coupling style is to be selected for this application. Since the SU Form coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice might be to seem at an SX or DI Sort coupling. The six bolt SX Variety will accommodate each parallel misalignment along with the defined shaft separation. The size will probably be determined through the selection torque and also the shaft diameters.
Stage two: Following, calculate the application torque and apply the support aspect to calculate the assortment torque.The formula employed to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging during the numbers in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Support Component = Choice Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Step three: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, greater than adequate to deal with the choice torque calculated in phase 2. The SX202-6, even so, won’t help the 92mm shaft dimension. The next greater size coupling, the SX228-6, will help the 92mm shaft dimension and the shaft separation dimension (BSE) is 6.88 inches, incredibly close to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly seem to be extreme, however, the coupling dimension is necessary to handle the bore size.
Step four: The SX228-6 coupling is rated for any greatest unbalanced velocity of three,400 RPM, over adequate to help the application speed of one,150 RPM.
Stage five: To find out should the coupling will take care of the parallel misalignment, use the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance involving disc packs or ??S?¡¥ dimension through the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It is actually often advised to seek to install the coupling at roughly 20% of your allowable misalignment. For this coupling the installer ought to seek to accomplish superior than 0.020 parallel misalignment at the time of set up. This will likely let for the more misalignment which will come about as the outcome of equipment settle and common tools wear.
