Techniques In Deciding on A Disc Coupling

The next is often a sample application used to illustrate the regular process for deciding on 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:
An organization includes a compressor application making use of a 225 horsepower electrical motor working at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft by using a 7/8 inch keyway plus the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is approximately 7 inches between shaft ends with some skill to alter the motor spot. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Phase 1: The primary phase is always to decide what coupling style is to be chosen for this application. Because the SU Kind coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference can be to search at an SX or DI Variety coupling. The six bolt SX Style will accommodate both parallel misalignment as well as defined shaft separation. The size will probably be determined from the assortment torque plus the shaft diameters.
Step 2: Up coming, determine the application torque and apply the services factor to calculate the assortment 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 in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Support Component = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage three: Use the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, in excess of ample to take care of the assortment torque calculated in step two. The SX202-6, nonetheless, will not support the 92mm shaft dimension. The next larger dimension coupling, the SX228-6, will support the 92mm shaft size and the shaft separation dimension (BSE) is 6.88 inches, incredibly near to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may well appear to be extreme, having said that, the coupling dimension is important to deal with the bore size.
Phase four: The SX228-6 coupling is rated for a maximum unbalanced pace of 3,400 RPM, over adequate to assistance the application velocity of one,150 RPM.
Step five: To find out if your coupling will take care of the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension through 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 your application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It really is always proposed to try to set up the coupling at approximately 20% of your allowable misalignment. For this coupling the installer ought to attempt to attain better than 0.020 parallel misalignment on the time of set up. This will likely enable for the extra misalignment that may occur as the outcome of tools settle and general gear wear.