The next is really a sample application employed to illustrate the common method for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company features a compressor application working with 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 that has a 7/8 inch keyway as well as compressor includes a 92mm shaft having a 25mm keyway. The shaft separation is roughly 7 inches in between shaft ends with some capability to adjust the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Step 1: The very first step would be to determine what coupling variety is to be picked for this application. Because the SU Sort coupling only supports
a single flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The next choice will be to search at an SX or DI Kind coupling. The 6 bolt SX Type will accommodate both parallel misalignment along with the defined shaft separation. The dimension are going to be established through the choice torque as well as shaft diameters.
Step two: Subsequent, calculate the application torque and apply the service element to calculate the assortment 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 during 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 Services Aspect = Assortment Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, a lot more than enough to handle the selection torque calculated in stage two. The SX202-6, even so, won’t assistance the 92mm shaft size. The next bigger dimension coupling, the SX228-6, will assistance the 92mm shaft size as well as the shaft separation dimension (BSE) is six.88 inches, quite close to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may appear to be extreme, nonetheless, the coupling dimension is critical to deal with the bore dimension.
Phase four: The SX228-6 coupling is rated to get a optimum unbalanced speed of three,400 RPM, more than sufficient to assistance the application speed of one,150 RPM.
Step 5: To find out in case the coupling will manage the parallel misalignment, make use of the trig perform of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension from the table on page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset to the application is 1/32 inches (0.031), therefore this coupling can accommodate the parallel misalignment.
Note: It is usually advised to make an effort to set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer should make an effort to attain better than 0.020 parallel misalignment on the time of set up. This will likely make it possible for for that added misalignment that can arise as the outcome of gear settle and standard products dress in.