The next is often a sample application applied to illustrate the conventional approach for picking 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:
An organization features a compressor application working with a 225 horsepower electrical motor working at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft with a 7/8 inch keyway as well as compressor includes a 92mm shaft with a 25mm keyway. The shaft separation is approximately seven inches between shaft ends with some capability to change the motor spot. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Phase 1: The initial phase is always to ascertain what coupling variety is usually to be selected for this application. Because the SU Style coupling only supports
just one flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The next selection might be to appear at an SX or DI Sort coupling. The 6 bolt SX Variety will accommodate the two parallel misalignment as well as defined shaft separation. The size will likely be established through the variety torque and also the shaft diameters.
Stage two: Subsequent, determine the application torque and apply the services aspect to determine the selection torque.The formula used to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Support Element = Assortment Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, a lot more than sufficient to take care of the selection torque calculated in stage two. The SX202-6, however, won’t assistance the 92mm shaft dimension. The next more substantial dimension coupling, the SX228-6, will support the 92mm shaft dimension along with the shaft separation dimension (BSE) is 6.88 inches, incredibly close to the application?¡¥s sought after seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be excessive, however, the coupling size is critical to take care of the bore size.
Phase four: The SX228-6 coupling is rated to get a highest unbalanced speed of 3,400 RPM, a lot more than sufficient to assistance the application speed of one,150 RPM.
Stage five: To determine in case the coupling will manage the parallel misalignment, utilize the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension in the table on web page D-13, or five.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), therefore this coupling can accommodate the parallel misalignment.
Note: It is often advised to make an effort to install the coupling at approximately 20% of the allowable misalignment. For this coupling the installer should really try and attain far better than 0.020 parallel misalignment with the time of installation. This may let to the extra misalignment that may occur as the end result of tools settle and standard gear dress in.