The next is usually a sample application made use of to illustrate the standard system 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:
A company has a compressor application applying a 225 horsepower electric motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft with a 7/8 inch keyway plus the compressor features a 92mm shaft with a 25mm keyway. The shaft separation is roughly seven inches between shaft ends with some potential to change the motor area. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The 1st step would be to establish what coupling type is usually to be chosen for this application. Because the SU Form coupling only supports
just one flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following decision can be to seem at an SX or DI Style coupling. The 6 bolt SX Form will accommodate both parallel misalignment as well as the defined shaft separation. The dimension might be established by the choice torque and also the shaft diameters.
Step 2: Next, determine the application torque and apply the service issue to determine the assortment torque.The formula utilized to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside 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 Support Component = Variety Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 3: Use the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, more than sufficient to handle the assortment torque calculated in stage two. The SX202-6, on the other hand, will not help the 92mm shaft size. The next larger dimension coupling, the SX228-6, will support the 92mm shaft size and also the shaft separation dimension (BSE) is six.88 inches, quite near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may well appear to be extreme, nevertheless, the coupling size is important to manage the bore dimension.
Step 4: The SX228-6 coupling is rated for any greatest unbalanced pace of three,400 RPM, in excess of enough to help the application pace of one,150 RPM.
Stage five: To find out if the coupling will deal with the parallel misalignment, make use of the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst 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 five.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It really is constantly proposed to make an effort to set up the coupling at approximately 20% with the allowable misalignment. For this coupling the installer must endeavor to attain much better than 0.020 parallel misalignment on the time of set up. This will let for the added misalignment that will take place since the outcome of tools settle and basic products put on.