The next is a sample application utilized to illustrate the normal system for selecting 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:
A company features a compressor application employing a 225 horsepower electric 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 which has a 7/8 inch keyway and the compressor has a 92mm shaft using a 25mm keyway. The shaft separation is roughly seven inches between shaft ends with some potential to modify the motor place. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Step one: The initial stage is to identify what coupling variety is usually to be selected for this application. Because the SU Form coupling only supports
just one flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The next selection will be to appear at an SX or DI Sort coupling. The six bolt SX Type will accommodate both parallel misalignment plus the defined shaft separation. The size will be determined from the choice torque and also the shaft diameters.
Phase 2: Upcoming, determine the application torque and apply the service aspect to determine the choice torque.The formula employed to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging while in the numbers from the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Support Component = Choice Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Stage three: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, a lot more than enough to deal with the choice torque calculated in phase 2. The SX202-6, on the other hand, won’t help the 92mm shaft dimension. The subsequent more substantial size coupling, the SX228-6, will assistance the 92mm shaft dimension plus the shaft separation dimension (BSE) is six.88 inches, really close to the application?¡¥s sought after seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, however, the coupling dimension is critical to deal with the bore size.
Stage four: The SX228-6 coupling is rated for a optimum unbalanced pace of three,400 RPM, greater than sufficient to assistance the application pace of one,150 RPM.
Stage five: To determine should the coupling will take care of the parallel misalignment, make use of the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension from your table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for your application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It is actually usually encouraged to try to set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer really should try and accomplish far better than 0.020 parallel misalignment on the time of set up. This will let for the additional misalignment that will happen because the end result of equipment settle and general equipment dress in.