The following is really a sample application utilized to illustrate the standard approach for selecting a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company has a compressor application making use of a 225 horsepower electric motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft with a 7/8 inch keyway plus the compressor has a 92mm shaft that has a 25mm keyway. The shaft separation is approximately 7 inches concerning shaft ends with some capability to change the motor location. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The initial stage should be to figure out what coupling form should be to be picked for this application. Because the SU Type coupling only supports
a single flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference would be to look at an SX or DI Variety coupling. The six bolt SX Kind will accommodate the two parallel misalignment and the defined shaft separation. The dimension might be determined from the variety torque as well as the shaft diameters.
Stage 2: Next, calculate the application torque and apply the support factor to calculate 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 inside the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Issue = Choice Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Utilize the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over sufficient to handle the variety torque calculated in step two. The SX202-6, even so, will not assistance the 92mm shaft size. The next more substantial size coupling, the SX228-6, will assistance the 92mm shaft size plus the shaft separation dimension (BSE) is six.88 inches, very 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 excessive, even so, the coupling size is important to handle the bore size.
Stage four: The SX228-6 coupling is rated for any highest unbalanced velocity of 3,400 RPM, greater than enough to assistance the application velocity of one,150 RPM.
Phase five: To determine in the event the coupling will manage the parallel misalignment, use the trig function of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance involving disc packs or ??S?¡¥ dimension through the table on webpage D-13, or 5.50 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), thus this coupling can accommodate the parallel misalignment.
Note: It can be always encouraged to endeavor to install the coupling at approximately 20% on the allowable misalignment. For this coupling the installer should really make an effort to accomplish improved than 0.020 parallel misalignment at the time of installation. This will likely permit for that extra misalignment that may occur because the consequence of tools settle and general products wear.