Steps In Picking A Disc Coupling

The following is a sample application made use of to illustrate the regular process for picking out 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 has a compressor application working with a 225 horsepower electrical motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft with a 7/8 inch keyway plus the compressor includes a 92mm shaft having a 25mm keyway. The shaft separation is roughly 7 inches concerning shaft ends with some capability to adjust the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage one: The 1st phase is to establish what coupling variety will be to be picked for this application. Because the SU Sort coupling only supports
just one flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following preference can be to search at an SX or DI Type coupling. The 6 bolt SX Kind will accommodate both parallel misalignment as well as the defined shaft separation. The size are going to be determined through the assortment torque as well as shaft diameters.
Step 2: Subsequent, calculate the application torque and apply the support component to determine the variety torque.The formula utilized 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 the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Services Issue = Selection Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Phase 3: Utilize the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, in excess of sufficient to handle the selection torque calculated in stage 2. The SX202-6, nonetheless, will not assistance the 92mm shaft dimension. The subsequent bigger dimension coupling, the SX228-6, will help the 92mm shaft dimension as well as shaft separation dimension (BSE) is 6.88 inches, really near to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be extreme, on the other hand, the coupling size is important to take care of the bore size.
Phase 4: The SX228-6 coupling is rated to get a highest unbalanced pace of three,400 RPM, more than sufficient to assistance the application speed of 1,150 RPM.
Step five: To find out if your coupling will manage the parallel misalignment, utilize the trig function of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension from your table on webpage D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The utmost offset for that application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It can be usually suggested to endeavor to set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer should try and achieve far better than 0.020 parallel misalignment with the time of installation. This can enable for that added misalignment that will arise since the result of products settle and general gear dress in.