The next can be a sample application utilised to illustrate the standard approach 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:
A company features a compressor application applying a 225 horsepower electric motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor includes 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 approximately 7 inches in between shaft ends with some means to modify the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Phase 1: The first step would be to establish what coupling form should be to be chosen for this application. Because the SU Form coupling only supports
a single flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The next choice will be to seem at an SX or DI Variety coupling. The 6 bolt SX Style will accommodate both parallel misalignment as well as the defined shaft separation. The dimension will be determined by the assortment torque and also the shaft diameters.
Phase two: Subsequent, calculate the application torque and apply the services factor to determine the selection torque.The formula utilised to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Aspect = Selection Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Stage three: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, greater than sufficient to deal with the variety torque calculated in step two. The SX202-6, even so, won’t support the 92mm shaft size. The subsequent more substantial dimension coupling, the SX228-6, will support the 92mm shaft size and also the shaft separation dimension (BSE) is 6.88 inches, extremely near to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly seem to be excessive, nonetheless, the coupling size is necessary to handle the bore dimension.
Step four: The SX228-6 coupling is rated to get a optimum unbalanced speed of 3,400 RPM, greater than enough to assistance the application pace of 1,150 RPM.
Step five: To determine in case the coupling will manage the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension in the table on web 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), as a result this coupling can accommodate the parallel misalignment.
Note: It can be constantly encouraged to seek to set up the coupling at approximately 20% from the allowable misalignment. For this coupling the installer ought to endeavor to realize improved than 0.020 parallel misalignment in the time of installation. This can make it possible for to the added misalignment that will occur since the end result of gear settle and basic gear put on.