The next is often a sample application applied to illustrate the common process for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization features a compressor application applying a 225 horsepower electrical motor operating at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft by using a 7/8 inch keyway and also the compressor includes a 92mm shaft having a 25mm keyway. The shaft separation is roughly seven inches among shaft ends with some skill to modify the motor place. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The 1st phase is always to ascertain what coupling kind is always to be selected for this application. Since the SU Variety coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next selection can be to search at an SX or DI Type coupling. The 6 bolt SX Form will accommodate both parallel misalignment along with the defined shaft separation. The size will probably be established by the selection torque as well as shaft diameters.
Step two: Following, determine the application torque and apply the services issue to determine the assortment 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 in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Services Aspect = Assortment Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Phase three: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, more than ample to manage the selection torque calculated in stage 2. The SX202-6, however, is not going to support the 
92mm shaft dimension. The subsequent bigger dimension coupling, the SX228-6, will support the 92mm shaft dimension and also the shaft separation dimension (BSE) is 6.88 inches, quite close to the application?¡¥s wanted 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be extreme, however, the coupling dimension is necessary to manage the bore dimension.
Phase 4: The SX228-6 coupling is rated to get a maximum unbalanced pace of three,400 RPM, a lot more than adequate to support the application speed of 1,150 RPM.
Step 5: To find out should the coupling will handle the parallel misalignment, utilize the trig perform of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension in the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It’s constantly recommended to attempt to set up the coupling at roughly 20% of the allowable misalignment. For this coupling the installer must seek to reach far better than 0.020 parallel misalignment on the time of set up. This may let for your more misalignment that will arise as the outcome of equipment settle and basic gear dress in.
