The following is really a sample application employed to illustrate the normal procedure for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization features a compressor application utilizing a 225 horsepower electrical motor operating at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft using a 7/8 inch keyway and also the compressor includes a 92mm shaft using a 25mm keyway. The shaft separation is approximately 7 inches among shaft ends with some ability to modify the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The very first phase is usually to determine what coupling sort should be to be selected for this application. Because the SU Kind coupling only supports
a single flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference would be to appear at an SX or DI Kind coupling. The six bolt SX Type will accommodate each parallel misalignment as well as defined shaft separation. The size will be established from the variety torque plus the shaft diameters.
Phase two: Up coming, calculate the application torque and apply the services factor to calculate the choice 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 from the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Services Aspect = Assortment Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Step three: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over ample to manage the choice torque calculated in phase 2. The SX202-6, nevertheless, is not going to assistance the 92mm shaft dimension. The following greater size coupling, the SX228-6, will assistance the 92mm shaft dimension along with the shaft separation dimension (BSE) is six.88 inches, pretty close to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may seem to be excessive, even so, the coupling dimension is necessary to handle the bore size.
Phase four: The SX228-6 coupling is rated for a maximum unbalanced velocity of 3,400 RPM, greater than sufficient to support the application velocity of 1,150 RPM.
Step 5: To determine in case the coupling will manage the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension from the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It is actually normally suggested to seek to set up the coupling at roughly 20% from the allowable misalignment. For this coupling the installer should really try to obtain greater than 0.020 parallel misalignment at the time of installation. This can allow for your additional misalignment that may come about because the consequence of equipment settle and standard gear dress in.