The following can be a sample application utilized to illustrate the common procedure for picking 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 has a compressor application making use of a 225 horsepower electrical motor operating at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft that has a 7/8 inch keyway as well as the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is approximately seven inches among shaft ends with some capability to modify the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The primary step would be to decide what coupling kind is always to be selected for this application. Because the SU Kind coupling only supports
just one flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The following option can be to appear at an SX or DI Kind coupling. The six bolt SX Form will accommodate each parallel misalignment as well as the defined shaft separation. The size will be established through the selection torque along with the shaft diameters.
Phase two: Next, calculate the application torque and apply the services aspect to calculate 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 during the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Support Component = Selection Torque
12,331 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, a lot more than enough to manage the assortment torque calculated in step 2. The SX202-6, however, is not going to assistance the 92mm shaft dimension. The following greater size coupling, the SX228-6, will support the 92mm shaft size and the shaft separation dimension (BSE) is six.88 inches, extremely near to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, however, the coupling dimension is important to manage the bore dimension.
Phase four: The SX228-6 coupling is rated for any maximum unbalanced velocity of three,400 RPM, over enough to help the application speed of 1,150 RPM.
Stage 5: To find out in the event the coupling will deal with the parallel misalignment, utilize the trig perform of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension through the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), as a result this coupling can accommodate the parallel misalignment.
Note: It really is generally suggested to attempt to install the coupling at approximately 20% in the allowable misalignment. For this coupling the installer should make an effort to realize better than 0.020 parallel misalignment in the time of installation. This will let for that supplemental misalignment that should occur since the end result of tools settle and common tools put on.