Steps In Choosing A Disc Coupling

The next is actually a sample application used to illustrate the regular method for choosing a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company has a compressor application making use of a 225 horsepower electrical motor working at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft having a 7/8 inch keyway along with the compressor includes a 92mm shaft by using a 25mm keyway. The shaft separation is roughly 7 inches between shaft ends with some ability to adjust the motor spot. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Stage one: The 1st step is to determine what coupling style is always to be picked for this application. Because the SU Variety coupling only supports
a single flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The following option would be to appear at an SX or DI Sort coupling. The 6 bolt SX Type will accommodate the two parallel misalignment as well as defined shaft separation. The size is going to be established from the variety torque as well as the shaft diameters.
Phase 2: Subsequent, calculate the application torque and apply the service component to calculate the choice torque.The formula applied to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging while in 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 Support Aspect = Selection Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Utilize the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, over adequate to take care of the selection torque calculated in phase 2. The SX202-6, nonetheless, won’t assistance the 92mm shaft size. The next larger size coupling, the SX228-6, will help the 92mm shaft size as well as shaft separation dimension (BSE) is 6.88 inches, really close to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be extreme, even so, the coupling size is important to manage the bore size.
Stage four: The SX228-6 coupling is rated to get a optimum unbalanced speed of three,400 RPM, over ample to support the application pace of 1,150 RPM.
Stage 5: To determine if your coupling will deal with 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 between disc packs or ??S?¡¥ dimension in 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 your application is 1/32 inches (0.031), for that reason this coupling can accommodate the parallel misalignment.
Note: It is actually normally recommended to make an effort to install the coupling at approximately 20% of the allowable misalignment. For this coupling the installer must seek to attain better than 0.020 parallel misalignment with the time of set up. This can let to the more misalignment that can happen because the result of gear settle and common tools dress in.