Steps In Picking A Disc Coupling

The following is often a sample application made use of to illustrate the regular course of action 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:
An organization has a compressor application working with a 225 horsepower electrical motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft which has a 7/8 inch keyway plus the compressor includes a 92mm shaft having a 25mm keyway. The shaft separation is approximately seven inches concerning shaft ends with some capability to adjust the motor area. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The initial phase is to establish what coupling kind is always to be picked for this application. Because the SU Sort coupling only supports
a single flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following decision can be to appear 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 dimension are going to be determined from the assortment torque as well as shaft diameters.
Step 2: Subsequent, calculate the application torque and apply the services component to determine the choice 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 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 Element = Selection Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, a lot more than sufficient to manage the selection torque calculated in stage 2. The SX202-6, nevertheless, will not assistance the 92mm shaft size. The following bigger dimension coupling, the SX228-6, will assistance the 92mm shaft dimension plus the 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 critical to take care of the bore size.
Phase 4: The SX228-6 coupling is rated for a optimum unbalanced speed of 3,400 RPM, more than enough to assistance the application velocity of 1,150 RPM.
Step five: To determine in the event the coupling will handle the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension from the table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It really is always recommended to try and set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer should really try and achieve far better than 0.020 parallel misalignment on the time of installation. This may permit to the added misalignment that should arise since the consequence of products settle and general gear put on.