The next is usually a sample application utilised to illustrate the normal 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:
An organization includes a compressor application applying a 225 horsepower electrical motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft that has a 7/8 inch keyway and the compressor includes a 92mm shaft that has a 25mm keyway. The shaft separation is roughly 7 inches concerning shaft ends with some means to alter the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Stage one: The initial phase is usually to establish what coupling type should be to be picked for this application. Because the SU Type coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent selection will be to appear at an SX or DI Variety coupling. The six bolt SX Style will accommodate each parallel misalignment as well as the defined shaft separation. The dimension might be established by the variety torque as well as shaft diameters.
Step two: Up coming, calculate the application torque and apply the support factor to calculate the selection torque.The formula utilized to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Support Issue = Selection Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Utilize the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, in excess of enough to deal with the assortment torque calculated in step 2. The SX202-6, even so, is not going to support the 92mm shaft dimension. The subsequent larger dimension coupling, the SX228-6, will assistance the 92mm shaft size plus the shaft separation dimension (BSE) is 6.88 inches, pretty near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be excessive, nonetheless, the coupling dimension is necessary to manage the bore dimension.
Stage four: The SX228-6 coupling is rated for a optimum unbalanced velocity of 3,400 RPM, a lot more than enough to help the application pace of one,150 RPM.
Step five: To find out should the coupling will manage the parallel misalignment, use the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension through the table on page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It really is often advised to endeavor to install the coupling at approximately 20% on the allowable misalignment. For this coupling the installer ought to make an effort to realize much better than 0.020 parallel misalignment in the time of set up. This can permit to the additional misalignment that will take place since the consequence of gear settle and standard gear dress in.