Steps In Choosing A Disc Coupling

The next is often a sample application applied to illustrate the standard method for choosing 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:
An organization includes a compressor application using 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 by using a 7/8 inch keyway and also the compressor features a 92mm shaft by using a 25mm keyway. The shaft separation is approximately 7 inches among shaft ends with some skill to alter the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The first phase is always to identify what coupling variety is always to be picked for this application. Because the SU Variety coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The following preference would be to appear at an SX or DI Style coupling. The 6 bolt SX Form will accommodate both parallel misalignment along with the defined shaft separation. The dimension is going to be established from the assortment torque plus the shaft diameters.
Step two: Next, calculate the application torque and apply the service aspect to determine the variety torque.The formula used to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within 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 Support Aspect = Assortment Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 3: Utilize the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, in excess of ample to manage the variety torque calculated in stage 2. The SX202-6, on the other hand, won’t help the 92mm shaft dimension. The subsequent greater size coupling, the SX228-6, will help the 92mm shaft size and the shaft separation dimension (BSE) is six.88 inches, incredibly close to the application?¡¥s sought after seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may seem to be extreme, having said that, the coupling dimension is critical to take care of the bore size.
Stage four: The SX228-6 coupling is rated to get a greatest unbalanced pace of three,400 RPM, more than ample to help the application velocity of 1,150 RPM.
Step five: To find out in the event 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 among disc packs or ??S?¡¥ dimension in the 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 to the application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It really is generally advisable to make an effort to install the coupling at roughly 20% from the allowable misalignment. For this coupling the installer should attempt to reach superior than 0.020 parallel misalignment with the time of set up. This will likely let for the extra misalignment which will occur because the consequence of tools settle and common equipment wear.



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