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Actions In Picking out A Disc Coupling

The next is often a sample application applied to illustrate the conventional procedure for choosing 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 applying a 225 horsepower electrical motor working at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft which has a 7/8 inch keyway along with the compressor features a 92mm shaft using a 25mm keyway. The shaft separation is roughly 7 inches in between shaft ends with some ability to adjust the motor spot. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The initial step will be to decide what coupling style is usually to be chosen for this application. Since the SU Form coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The following alternative will be to appear at an SX or DI Kind coupling. The six bolt SX Sort will accommodate the two parallel misalignment and also the defined shaft separation. The size will be determined by the selection torque plus the shaft diameters.
Stage 2: Subsequent, determine the application torque and apply the services factor to calculate the assortment 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 within the numbers in the 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
Phase 3: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, more than ample to manage the variety torque calculated in phase two. The SX202-6, on the other hand, won’t assistance the 92mm shaft dimension. The next bigger size coupling, the SX228-6, will assistance the 92mm shaft dimension plus the shaft separation dimension (BSE) is six.88 inches, very close to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be excessive, even so, the coupling dimension is important to handle the bore dimension.
Phase four: The SX228-6 coupling is rated for a greatest unbalanced speed of 3,400 RPM, a lot more than sufficient to help the application pace of one,150 RPM.
Step five: To find out in case the coupling will handle the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension from 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 the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It can be constantly recommended to attempt to set up the coupling at roughly 20% from the allowable misalignment. For this coupling the installer must attempt to reach better than 0.020 parallel misalignment at the time of installation. This will enable to the supplemental misalignment that can arise because the consequence of equipment settle and general products put on.


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