The following is usually a sample application employed to illustrate the common course of action for picking out a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
A company has a compressor application employing a 225 horsepower electric motor running at one,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 as well as compressor features a 92mm shaft by using a 25mm keyway. The shaft separation is approximately seven inches involving shaft ends with some capability to alter the motor location. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Step 1: The primary step should be to determine what coupling variety is always to be selected for this application. Since the SU Form coupling only supports
a single flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next choice can be to seem at an SX or DI Style coupling. The six bolt SX Style will accommodate each parallel misalignment along with the defined shaft separation. The dimension will probably be established from the assortment torque as well as shaft diameters.
Phase two: Subsequent, determine the application torque and apply the services factor to determine the assortment torque.The formula utilized to determine 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 Support Component = Choice Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Utilize the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, greater than adequate to handle the variety torque calculated in phase two. The SX202-6, nevertheless, is not going to support the 92mm shaft dimension. The next bigger size coupling, the SX228-6, will assistance the 92mm shaft dimension and the shaft separation dimension (BSE) is 6.88 inches, extremely close to the application?¡¥s sought after seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be extreme, however, the coupling size is critical to deal with the bore size.
Phase four: The SX228-6 coupling is rated for any maximum unbalanced velocity of three,400 RPM, more than sufficient to help the application velocity of 1,150 RPM.
Phase five: To find out when the coupling will take care of the parallel misalignment, make use of 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 webpage D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It can be usually advised to endeavor to install the coupling at approximately 20% from the allowable misalignment. For this coupling the installer really should try to attain better than 0.020 parallel misalignment with the time of set up. This will allow to the extra misalignment that can arise because the consequence of equipment settle and general tools put on.
