Methods In Choosing A Disc Coupling

The following can be a sample application used to illustrate the standard approach for deciding on 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 applying a 225 horsepower electric motor working at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft using a 7/8 inch keyway as well as compressor features a 92mm shaft that has a 25mm keyway. The shaft separation is approximately seven inches between shaft ends with some capacity to alter the motor spot. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The 1st phase is usually to ascertain what coupling type would be to be selected for this application. Because the SU Variety coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The following option will be to search at an SX or DI Style coupling. The 6 bolt SX Sort will accommodate the two parallel misalignment along with the defined shaft separation. The dimension will likely be established from the selection torque as well as shaft diameters.
Stage 2: Upcoming, determine the application torque and apply the services issue to determine the variety 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 inside the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Component = Selection 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 adequate to handle the assortment torque calculated in step 2. The SX202-6, however, will not assistance the 92mm shaft dimension. The next larger size coupling, the SX228-6, will help the 92mm shaft size as well as shaft separation dimension (BSE) is 6.88 inches, pretty near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be extreme, having said that, the coupling dimension is important to manage the bore size.
Stage 4: The SX228-6 coupling is rated for any optimum unbalanced velocity of three,400 RPM, in excess of adequate to support the application velocity of 1,150 RPM.
Step five: To find out if the coupling will take care of the parallel misalignment, utilize the trig function of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension from your table on web page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset for that application is 1/32 inches (0.031), for that reason this coupling can accommodate the parallel misalignment.
Note: It is actually constantly advisable to try to set up the coupling at approximately 20% with the allowable misalignment. For this coupling the installer should try to accomplish improved than 0.020 parallel misalignment in the time of installation. This may let to the supplemental misalignment that can take place because the consequence of tools settle and common tools dress in.

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