The following is often a sample application utilised to illustrate the typical procedure for picking out 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 includes a compressor application working with a 225 horsepower electric motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft having a 7/8 inch keyway and the compressor includes a 92mm shaft with a 25mm keyway. The shaft separation is roughly seven inches concerning shaft ends with some skill to modify the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The 1st stage will be to figure out what coupling type should be to be picked for this application. Since the SU Type coupling only supports
just one flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The following decision will be to search at an SX or DI Form coupling. The 6 bolt SX Sort will accommodate each parallel misalignment plus the defined shaft separation. The dimension might be determined from the selection torque as well as the shaft diameters.
Phase two: Up coming, calculate the application torque and apply the service aspect to calculate the choice torque.The formula used to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging in 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 Factor = Selection Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Stage three: Utilize the SX coupling tables and note that the SX 202-6 is 
rated at 40,700 in-lbs, more than adequate to handle the selection torque calculated in stage two. The SX202-6, however, will not support the 92mm shaft dimension. The next more substantial dimension coupling, the SX228-6, will support the 92mm shaft dimension and also the shaft separation dimension (BSE) is six.88 inches, very near to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may appear to be excessive, having said that, the coupling size is important to manage the bore dimension.
Phase 4: The SX228-6 coupling is rated to get a greatest unbalanced pace of three,400 RPM, greater than enough to help the application velocity of 1,150 RPM.
Phase five: To find out if your coupling will deal with the parallel misalignment, make use of the trig perform of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension from the table on web page D-13, or five.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), for that reason this coupling can accommodate the parallel misalignment.
Note: It truly is often proposed to attempt to install the coupling at approximately 20% in the allowable misalignment. For this coupling the installer must seek to accomplish far better than 0.020 parallel misalignment with the time of set up. This may let for the additional misalignment that may come about as the end result of products settle and basic equipment put on.
