January 26, 2021

The next can be a sample application used to illustrate the common system for deciding on 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 includes a compressor application making use of a 225 horsepower electric motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft having a 7/8 inch keyway as well as the compressor includes a 92mm shaft that has a 25mm keyway. The shaft separation is roughly 7 inches concerning shaft ends with some capability to modify the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Step 1: The first step will be to ascertain what coupling style is usually to be picked for this application. Because the SU Type coupling only supports
a single flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next decision might be to search at an SX or DI Sort coupling. The 6 bolt SX Type will accommodate each parallel misalignment and the defined shaft separation. The size will likely be determined through the selection torque plus the shaft diameters.
Phase 2: Up coming, determine the application torque and apply the service element to calculate the variety torque.The formula made use of to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging during 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 Factor = Variety 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 40,700 in-lbs, over sufficient to manage the selection torque calculated in step two. The SX202-6, even so, will not assistance the 92mm shaft dimension. The subsequent greater size coupling, the SX228-6, will support the 92mm shaft size and also the shaft separation dimension (BSE) is 6.88 inches, pretty close to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may seem to be excessive, nevertheless, the coupling size is necessary to manage the bore size.
Phase four: The SX228-6 coupling is rated to get a maximum unbalanced pace of 3,400 RPM, more than sufficient to assistance the application speed of 1,150 RPM.
Step 5: To find out if your coupling will take care of the parallel misalignment, make use of the trig perform of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension from your table on page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for your application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It truly is generally proposed to endeavor to install the coupling at roughly 20% in the allowable misalignment. For this coupling the installer really should endeavor to reach far better than 0.020 parallel misalignment at the time of set up. This will likely enable to the additional misalignment which will occur because the end result of tools settle and basic tools wear.