The following is a sample application utilized to illustrate the typical approach for selecting a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization has a compressor application making use of a 225 horsepower electric motor working at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft by using a 7/8 inch keyway plus the compressor includes a 92mm shaft with a 25mm keyway. The shaft separation is approximately seven inches concerning shaft ends with some skill to change the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Step 1: The 1st stage is to identify what coupling form should be 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 option will be to look at an SX or DI Sort coupling. The 6 bolt SX Sort will accommodate the two parallel misalignment and the defined shaft separation. The dimension might be established by the assortment torque as well as the shaft diameters.
Step 2: Up coming, calculate the application torque and apply the services component 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 during 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 Services Factor = Selection Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Use the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, more than ample to manage the assortment torque calculated in stage two. The SX202-6, on the other hand, is not going to support the 92mm shaft size. The subsequent bigger dimension coupling, the SX228-6, will assistance the 92mm shaft size and also the shaft separation dimension (BSE) is six.88 inches, really close to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which could seem to be excessive, having said that, the coupling dimension is necessary to manage the bore dimension.
Step four: The SX228-6 coupling is rated for a greatest unbalanced velocity of 3,400 RPM, more than enough to help the application pace of 1,150 RPM.
Phase 5: To find out if your 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 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 utmost offset for the application is 1/32 inches (0.031), for that reason this coupling can accommodate the parallel misalignment.
Note: It is actually generally advisable to attempt to install the coupling at roughly 20% in the allowable misalignment. For this coupling the installer must attempt to achieve much better than 0.020 parallel misalignment with the time of installation. This will permit for your further misalignment which will arise as the consequence of tools settle and common gear dress in.