The next is often a sample application applied to illustrate the regular course of action for picking out 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:
A company features a compressor application using a 225 horsepower electric motor operating at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft by using a 7/8 inch keyway and also the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is approximately 7 inches among shaft ends with some ability to modify the motor area. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step 1: The very first step is always to ascertain what coupling style is to be chosen for this application. Because the SU Style coupling only supports
a single flex plane, it could only accommodate angular and axial misalignment, but not parallel misalignment. The next choice can be to seem at an SX or DI Form coupling. The 6 bolt SX Type will accommodate both parallel misalignment along with the defined shaft separation. The size will probably be determined from the selection torque and also the shaft diameters.
Phase two: Subsequent, determine the application torque and apply the support aspect 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 while in the numbers from the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Element = 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, over adequate to manage the assortment torque calculated in step 2. The SX202-6, on the other hand, is not going to assistance the 92mm shaft size. The subsequent more substantial dimension coupling, the SX228-6, will assistance the 92mm shaft size and also the shaft separation dimension (BSE) is 6.88 inches, really close to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may well seem to be excessive, nonetheless, the coupling size is critical to handle the bore dimension.
Step four: The SX228-6 coupling is rated for any optimum unbalanced speed of three,400 RPM, over enough to assistance the application velocity of 1,150 RPM.
Stage 5: To determine in case the coupling will take care of the parallel misalignment, use the trig perform of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance between disc packs or ??S?¡¥ dimension in the table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset to the application is 1/32 inches (0.031), for that reason this coupling can accommodate the parallel misalignment.
Note: It is actually constantly proposed to seek to set up the coupling at roughly 20% in the allowable misalignment. For this coupling the installer must seek to reach better than 0.020 parallel misalignment on the time of installation. This can allow to the more misalignment that will happen as the end result of tools settle and basic tools dress in.