Steps In Picking out A Disc Coupling

The next is a sample application used to illustrate the conventional method for picking out 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:
A company includes a compressor application making use of a 225 horsepower electric motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft which has a 7/8 inch keyway along with the compressor has a 92mm shaft by using a 25mm keyway. The shaft separation is approximately 7 inches involving shaft ends with some ability to change the motor spot. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Step one: The very first step will be to determine what coupling variety will be to be chosen for this application. Because the SU Style coupling only supports
a single flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The following alternative would be to seem at an SX or DI Sort coupling. The six bolt SX Type will accommodate each parallel misalignment as well as defined shaft separation. The dimension is going to be determined from the choice torque as well as the shaft diameters.
Stage 2: Next, calculate the application torque and apply the support component to determine the choice torque.The formula employed 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 Support Element = Selection Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over enough to take care of the choice torque calculated in phase two. The SX202-6, nonetheless, will not assistance the 92mm shaft size. The next greater size coupling, the SX228-6, will assistance the 92mm shaft size along with the shaft separation dimension (BSE) is six.88 inches, very close to the application?¡¥s sought after seven 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 important to take care of the bore size.
Step four: The SX228-6 coupling is rated for any optimum unbalanced velocity of three,400 RPM, more than ample to assistance the application velocity of one,150 RPM.
Stage five: To determine when the coupling will deal with the parallel misalignment, use the trig function of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension from your table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for that application is 1/32 inches (0.031), for that reason this coupling can accommodate the parallel misalignment.
Note: It truly is normally advisable to try and set up the coupling at approximately 20% in the allowable misalignment. For this coupling the installer really should attempt to attain superior than 0.020 parallel misalignment with the time of installation. This can allow to the additional misalignment that can come about because the end result of tools settle and standard tools wear.


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