The next is a sample application employed to illustrate the regular approach for choosing 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:
An organization includes a compressor application employing a 225 horsepower electrical motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft having a 7/8 inch keyway and also the compressor includes a 92mm shaft that has a 25mm keyway. The shaft separation is roughly seven inches concerning shaft ends with some ability to change the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The first step is always to ascertain what coupling kind would be to be chosen for this application. Since the SU Sort coupling only supports
a single flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next preference might be to appear at an SX or DI Kind coupling. The six bolt SX Sort will accommodate both parallel misalignment along with the defined shaft separation. The dimension will likely be determined by the selection torque plus the shaft diameters.
Phase 2: Following, calculate the application torque and apply the services factor to calculate the variety torque.The formula employed to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Issue = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, more than adequate to handle the assortment torque calculated in step two. The SX202-6, having said that, will not assistance the 92mm shaft size. The subsequent greater dimension coupling, the SX228-6, will assistance the 92mm shaft dimension as well as the shaft separation dimension (BSE) is 6.88 inches, really close to the application?¡¥s wanted 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, even so, the coupling size is critical to handle the bore dimension.
Phase four: The SX228-6 coupling is rated for any greatest unbalanced pace of three,400 RPM, more than ample to help the application pace of 1,150 RPM.
Phase 5: To determine if your coupling will deal with the parallel misalignment, utilize 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 from your table on web page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for that application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It really is usually advised to try and set up the coupling at roughly 20% from the allowable misalignment. For this coupling the installer must try and obtain better than 0.020 parallel misalignment in the time of set up. This will enable for your extra misalignment that could come about as the consequence of equipment settle and standard tools dress in.