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The next is really a sample application employed to illustrate the typical system for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company has a compressor application utilizing a 225 horsepower electrical motor working at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft with a 7/8 inch keyway and also the compressor has a 92mm shaft with a 25mm keyway. The shaft separation is approximately 7 inches involving shaft ends with some capacity to modify the motor location. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The initial step would be to determine what coupling form would be to be picked for this application. Because the SU Kind coupling only supports
just one flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice will be to appear at an SX or DI Kind coupling. The 6 bolt SX Sort will accommodate each parallel misalignment as well as defined shaft separation. The size might be established through the selection torque and the shaft diameters.
Stage two: Following, determine the application torque and apply the service 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 in the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Services Element = Variety Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, more than sufficient to manage the variety torque calculated in stage two. The SX202-6, nevertheless, will not help the 92mm shaft size. The following more substantial size coupling, the SX228-6, will assistance the 92mm shaft dimension as well as shaft separation dimension (BSE) is 6.88 inches, quite close to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may appear to be extreme, nevertheless, the coupling dimension is necessary to deal with the bore dimension.
Step four: The SX228-6 coupling is rated to get a greatest unbalanced velocity of 3,400 RPM, over enough to help the application velocity of 1,150 RPM.
Stage five: To determine should the coupling will handle the parallel misalignment, make use of the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension through the table on page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset for that application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It can be normally advised to make an effort to set up the coupling at roughly 20% in the allowable misalignment. For this coupling the installer must endeavor to realize improved than 0.020 parallel misalignment on the time of installation. This may permit for the more misalignment that could occur since the consequence of equipment settle and standard tools dress in.