Actions In Deciding on A Disc Coupling

The next is really a sample application made use of to illustrate the conventional procedure 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 electrical motor operating at 1,150 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 with a 25mm keyway. The shaft separation is approximately 7 inches in between shaft ends with some potential to adjust the motor area. 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 should 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 decision 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 might be established through the selection torque and also the shaft diameters.
Stage 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 from your 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: Make use of 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 stage 2. The SX202-6, even so, will not help 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 preferred 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may well appear to be excessive, even so, the coupling dimension is necessary to take care of the bore size.
Stage 4: The SX228-6 coupling is rated to get a optimum unbalanced speed of 3,400 RPM, over adequate to support the application speed of one,150 RPM.
Stage 5: To determine if your coupling will deal with 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), consequently this coupling can accommodate the parallel misalignment.
Note: It’s generally proposed to try to set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer should make an effort to realize far better than 0.020 parallel misalignment in the time of installation. This can enable for the more misalignment that should occur since the result of gear settle and basic products dress in.


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