Actions In Deciding on A Disc Coupling

The next can be a sample application applied to illustrate the standard procedure 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:
An organization features a compressor application employing a 225 horsepower electric motor operating at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft that has a 7/8 inch keyway along with the compressor features a 92mm shaft using a 25mm keyway. The shaft separation is approximately 7 inches between shaft ends with some ability to alter the motor place. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage one: The 1st stage is usually to decide what coupling sort should be to be selected for this application. Since the SU Style coupling only supports
a single flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next decision might be to search at an SX or DI Variety coupling. The 6 bolt SX Style will accommodate the two parallel misalignment and also the defined shaft separation. The dimension will be determined by the choice torque plus the shaft diameters.
Phase 2: Next, calculate the application torque and apply the support element to determine the choice torque.The formula made use of to calculate 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 = 12,331 in-lbs
Application Torque x Support Component = Assortment Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Phase three: Utilize the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, over ample to take care of the assortment torque calculated in phase 2. The SX202-6, on the other hand, won't support the 92mm shaft size. The subsequent larger dimension coupling, the SX228-6, will help the 92mm shaft size and also the shaft separation dimension (BSE) is six.88 inches, pretty near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, even so, the coupling dimension is critical to manage the bore size.
Phase four: The SX228-6 coupling is rated for any maximum unbalanced speed of three,400 RPM, in excess of sufficient to assistance the application pace of one,150 RPM.
Phase 5: To determine in the event the coupling will manage the parallel misalignment, utilize the trig perform of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension in 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 the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It's usually proposed to seek to set up the coupling at approximately 20% with the allowable misalignment. For this coupling the installer really should try to attain much better than 0.020 parallel misalignment at the time of set up. This will likely let for your additional misalignment that will take place as the result of gear settle and basic equipment wear.