The next is really a sample application used to illustrate the standard approach for selecting a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization features a compressor application applying a 225 horsepower electric motor working at one,150 RPM to drive a 3 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 that has a 25mm keyway. The shaft separation is roughly 7 inches involving shaft ends with some skill to modify the motor spot. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Phase 1: The primary stage is usually to ascertain what coupling type would be to be chosen 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 following alternative will be to seem at an SX or DI Kind coupling. The 6 bolt SX Form will accommodate each parallel misalignment along with the defined shaft separation. The dimension will likely be established through the assortment torque as well as the shaft diameters.
Phase 2: Next, determine the application torque and apply the support factor to determine the selection torque.The formula utilised to calculate 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 Services Element = Assortment Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Phase three: Use the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over ample to take care of the assortment torque calculated in step two. The SX202-6, nonetheless, will not support the 92mm shaft dimension. The subsequent larger size coupling, the SX228-6, will support the 92mm shaft dimension plus the shaft separation dimension (BSE) is six.88 inches, quite near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may well seem to be extreme, even so, the coupling dimension is critical to manage the bore dimension.
Step four: The SX228-6 coupling is rated for a maximum unbalanced velocity of three,400 RPM, in excess of ample to assistance the application velocity of 1,150 RPM.
Phase five: To determine in the event the coupling will handle the parallel misalignment, use 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 webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It is actually usually recommended to attempt to install the coupling at roughly 20% in the allowable misalignment. For this coupling the installer really should endeavor to attain much better than 0.020 parallel misalignment in the time of set up. This can allow for your additional misalignment that will take place since the outcome of equipment settle and standard equipment dress in.