The next is really a sample application used to illustrate the typical course of action for choosing a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization includes a compressor application making use of a 225 horsepower electric motor running at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft using a 7/8 inch keyway plus the compressor has a 92mm shaft having a 25mm keyway. The shaft separation is roughly 7 inches among shaft ends with some capability to alter the motor location. The shafts possess a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The primary stage would be to establish what coupling form is always to be chosen for this application. Since the SU Type coupling only supports
just one flex plane, it could possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next decision might be to search at an SX or DI Type coupling. The 6 bolt SX Variety will accommodate each parallel misalignment as well as the defined shaft separation. The size is going to be established through the variety torque as well as shaft diameters.
Phase two: Next, calculate the application torque and apply the services component to determine the selection torque.The formula utilised 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 Support Factor = Choice Torque
12,331 in-lbs x three.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, greater than sufficient to handle the variety torque calculated in step two. The SX202-6, even so, is not going to assistance the 92mm shaft dimension. The following larger dimension coupling, the SX228-6, will help the 92mm shaft dimension as well as shaft separation dimension (BSE) is six.88 inches, quite near to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may well seem to be excessive, on the other hand, the coupling size is critical to manage the bore size.
Stage 4: The SX228-6 coupling is rated to get a greatest unbalanced velocity of three,400 RPM, over ample to help the application speed of one,150 RPM.
Step 5: To determine in the event the coupling will deal with the parallel misalignment, utilize the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension in the 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), as a result this coupling can accommodate the parallel misalignment.
Note: It is generally proposed to seek to set up the coupling at roughly 20% with the allowable misalignment. For this coupling the installer need to endeavor to attain greater than 0.020 parallel misalignment on the time of set up. This will likely make it possible for for that extra misalignment that may take place as the consequence of products settle and general products dress in.