Measures In Choosing A Disc Coupling

The following is actually a sample application employed to illustrate the regular course of action for choosing 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 has a compressor application employing a 225 horsepower electric motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft having a 7/8 inch keyway as well as compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is roughly 7 inches between shaft ends with some capacity to adjust the motor location. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The primary stage is to decide what coupling style is to be picked for this application. Since the SU Kind coupling only supports
just one flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice could be to look at an SX or DI Form coupling. The 6 bolt SX Sort will accommodate the two parallel misalignment and also the defined shaft separation. The size are going to be determined through the variety torque along with the shaft diameters.
Phase 2: Subsequent, calculate the application torque and apply the service aspect to calculate the variety torque.The formula utilised 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 Service Component = Variety Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Stage three: Utilize the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, a lot more than sufficient to handle the variety torque calculated in step 2. The SX202-6, on the other hand, won’t help the 92mm shaft size. The following more substantial size coupling, the SX228-6, will help the 92mm shaft dimension as well as shaft separation dimension (BSE) is six.88 inches, extremely near to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps seem to be extreme, on the other hand, the coupling size is important to handle the bore dimension.
Stage 4: The SX228-6 coupling is rated for a greatest unbalanced speed of 3,400 RPM, over enough to help the application velocity of one,150 RPM.
Phase 5: To find out in case the coupling will take care of the parallel misalignment, make use of the trig perform of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension from the table on webpage D-13, or 5.50 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), hence this coupling can accommodate the parallel misalignment.
Note: It is actually usually proposed to seek to install the coupling at roughly 20% with the allowable misalignment. For this coupling the installer should try and obtain better than 0.020 parallel misalignment at the time of installation. This will permit for that further misalignment that could happen since the result of products settle and common products put on.