ep

January 26, 2021

The next is usually a sample application used to illustrate the normal method for picking out a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization has a compressor application utilizing a 225 horsepower electric motor operating at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft using a 7/8 inch keyway as well as the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is roughly 7 inches involving shaft ends with some potential to alter the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The primary stage should be to ascertain what coupling variety will be to be picked for this application. Because the SU Variety coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice could be to seem at an SX or DI Kind coupling. The six bolt SX Kind will accommodate each parallel misalignment as well as defined shaft separation. The dimension is going to be determined through the assortment torque and also the shaft diameters.
Phase 2: Subsequent, calculate the application torque and apply the services issue 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 from 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 Service Component = Selection Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage three: Utilize the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, in excess of adequate to manage the variety torque calculated in step two. The SX202-6, nonetheless, is not going to help the 92mm shaft dimension. The subsequent larger dimension coupling, the SX228-6, will assistance the 92mm shaft size and the shaft separation dimension (BSE) is six.88 inches, extremely near to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be extreme, on the other hand, the coupling size is important to deal with the bore dimension.
Phase four: The SX228-6 coupling is rated for any highest unbalanced velocity of 3,400 RPM, in excess of ample to help the application speed of 1,150 RPM.
Stage five: To determine in case the 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 among disc packs or ??S?¡¥ dimension from your table on webpage 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), as a result this coupling can accommodate the parallel misalignment.
Note: It can be constantly advised to try to install the coupling at roughly 20% from the allowable misalignment. For this coupling the installer ought to seek to reach improved than 0.020 parallel misalignment on the time of set up. This will likely allow for the extra misalignment that will take place since the end result of gear settle and general equipment put on.