The next is often a sample application utilized to illustrate the common method for selecting a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company includes 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 electrical motor features a 3-3/8 inch shaft which has a 7/8 inch keyway as well as the compressor has a 92mm shaft which has a 25mm keyway. The shaft separation is approximately seven inches amongst shaft ends with some potential to adjust the motor area. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Step 1: The initial phase is always to figure out what coupling type is always to be picked for this application. Because the SU Sort coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent alternative could be to appear at an SX or DI Style coupling. The 6 bolt SX Sort will accommodate each parallel misalignment as well as the defined shaft separation. The dimension will be determined by the selection torque plus the shaft diameters.
Phase two: Up coming, determine the application torque and apply the support factor to calculate the selection torque.The formula used to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from 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 Service Factor = Choice Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 3: Utilize the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, a lot more than enough to deal with the variety torque calculated in step two. The SX202-6, however, won’t help the 92mm shaft size. The subsequent larger size coupling, the SX228-6, will assistance the 92mm shaft size along with the shaft separation dimension (BSE) is 6.88 inches, really near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may seem to be excessive, nonetheless, the coupling dimension is necessary to handle the bore dimension.
Stage 4: The SX228-6 coupling is rated to get a highest unbalanced velocity of three,400 RPM, greater than enough to support the application speed of 1,150 RPM.
Phase 5: To determine in case the coupling will handle the parallel misalignment, use the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension from your table on page D-13, or five.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), for that reason this coupling can accommodate the parallel misalignment.
Note: It’s always advised to try and install the coupling at roughly 20% of the allowable misalignment. For this coupling the installer should try and realize improved than 0.020 parallel misalignment on the time of set up. This may make it possible for for your added misalignment which will happen as the outcome of gear settle and standard tools dress in.