Actions In Deciding on A Disc Coupling

The next is really a sample application applied to illustrate the conventional process for choosing a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization features a compressor application using a 225 horsepower electric motor operating at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft that has a 7/8 inch keyway and also the compressor includes a 92mm shaft which has a 25mm keyway. The shaft separation is approximately 7 inches between shaft ends with some potential to adjust the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Stage one: The first stage would be to decide what coupling style will be to be chosen for this application. Since the SU Type coupling only supports
a single flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent selection would be to appear at an SX or DI Kind coupling. The 6 bolt SX Sort will accommodate the two parallel misalignment as well as defined shaft separation. The size is going to be established through the selection torque and also the shaft diameters.
Step 2: Following, determine the application torque and apply the support element to calculate 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 within the numbers in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Aspect = Assortment Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 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 selection torque calculated in step 2. The SX202-6, even so, will not assistance the 92mm shaft size. The following greater dimension coupling, the SX228-6, will help the 92mm shaft size as well as the shaft separation dimension (BSE) is six.88 inches, quite near to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may well appear to be excessive, nonetheless, the coupling dimension is important to take care of the bore size.
Step 4: The SX228-6 coupling is rated for a optimum unbalanced speed of 3,400 RPM, greater than adequate to support the application speed of 1,150 RPM.
Step 5: To determine if your coupling will handle the parallel misalignment, utilize the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension in the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for your application is 1/32 inches (0.031), therefore this coupling can accommodate the parallel misalignment.
Note: It is constantly encouraged to try to set up the coupling at approximately 20% on the allowable misalignment. For this coupling the installer should make an effort to obtain far better than 0.020 parallel misalignment in the time of installation. This can enable for that added misalignment that should come about since the result of gear settle and common products dress in.