The following is often a sample application utilised to illustrate the conventional system for picking out a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization features a compressor application using a 225 horsepower electric motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft using a 7/8 inch keyway and the compressor has a 92mm shaft that has a 25mm keyway. The shaft separation is roughly 7 inches among shaft ends with some skill to change the motor area. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Phase 1: The first phase should be to figure out what coupling type is usually to be selected for this application. Since the SU Variety coupling only supports
just one flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice will be to search at an SX or DI Form coupling. The six bolt SX Form will accommodate each parallel misalignment along with the defined shaft separation. The size will likely be established through the choice torque and the shaft diameters.
Step 2: Subsequent, calculate the application torque and apply the service component to calculate the variety torque.The formula made use of to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within 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 Service Issue = Assortment Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Make use of the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, over adequate to handle the choice torque calculated in step two. The SX202-6, nevertheless, is not going to help the 92mm shaft size. The subsequent bigger dimension coupling, the SX228-6, will support the 92mm shaft dimension and the shaft separation dimension (BSE) is 6.88 inches, extremely near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be extreme, even so, the coupling dimension is necessary to deal with the bore dimension.
Stage four: The SX228-6 coupling is rated for a maximum unbalanced velocity of three,400 RPM, greater than adequate to help the application velocity of one,150 RPM.
Stage five: To find out in case the coupling will manage the parallel misalignment, use the trig function 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 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 for that application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It is generally advised to make an effort to set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer really should endeavor to accomplish greater than 0.020 parallel misalignment at the time of installation. This can make it possible for for the added misalignment that should take place as the outcome of products settle and common tools put on.