The next can be a sample application made use of to illustrate the typical course of action for choosing 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 using a 225 horsepower electrical motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft that has a 7/8 inch keyway and the compressor features a 92mm shaft having a 25mm keyway. The shaft separation is roughly seven inches involving shaft ends with some capacity to modify the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase 1: The first step would be to figure out what coupling sort will be to be picked for this application. Since the SU Variety coupling only supports
just one flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next option could be to look at an SX or DI Variety coupling. The six bolt SX Form will accommodate each parallel misalignment and the defined shaft separation. The size is going to be determined by the choice torque as well as the shaft diameters.
Step 2: Upcoming, determine the application torque and apply the services element to determine the choice torque.The formula applied to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from the numbers from the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Service Aspect = Selection Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 3: Make use of the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, in excess of enough to deal with the variety torque calculated in stage two. The SX202-6, nevertheless, will not help the 92mm shaft dimension. The following bigger dimension coupling, the SX228-6, will support the 92mm shaft dimension as well as the shaft separation dimension (BSE) is 6.88 inches, really close to the application?¡¥s preferred 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be extreme, nevertheless, the coupling size is critical to deal with the bore size.
Step four: The SX228-6 coupling is rated for a greatest unbalanced velocity of 3,400 RPM, greater than adequate to assistance the application speed of one,150 RPM.
Phase 5: To determine if the coupling will handle the parallel misalignment, utilize the trig perform 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 page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for your application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It truly is constantly proposed to try and set up the coupling at approximately 20% of your allowable misalignment. For this coupling the installer should make an effort to accomplish improved than 0.020 parallel misalignment with the time of installation. This can allow for that additional misalignment that could come about as the outcome of equipment settle and basic tools put on.