The next is actually a sample application utilised to illustrate the conventional process for picking out a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company has a compressor application making use of a 225 horsepower electric motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft by using a 7/8 inch keyway as well as the compressor features a 92mm shaft having a 25mm keyway. The shaft separation is approximately 7 inches concerning shaft ends with some skill to modify the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step one: The primary stage is always to figure out what coupling kind will be to be picked for this application. Since the SU Variety coupling only supports
a single flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The next selection can be to appear at an SX or DI Sort coupling. The 6 bolt SX Variety will accommodate each parallel misalignment as well as defined shaft separation. The dimension are going to be determined through the selection torque as well as the shaft diameters.
Stage two: Upcoming, calculate the application torque and apply the services aspect to determine the selection torque.The formula applied to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Support Issue = Variety Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Make use of the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, greater than adequate to manage the variety torque calculated in stage 2. The SX202-6, even so, will not help the 92mm shaft dimension. The following more substantial dimension coupling, the SX228-6, will assistance the 92mm shaft dimension and the shaft separation dimension (BSE) is six.88 inches, incredibly close to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be extreme, nonetheless, the coupling dimension is critical to deal with the bore dimension.
Phase four: The SX228-6 coupling is rated to get a greatest unbalanced velocity of 3,400 RPM, a lot more than enough to support the application speed of 1,150 RPM.
Stage five: To determine when 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 involving disc packs or ??S?¡¥ dimension from 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 utmost offset for that application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It is actually always encouraged to try and set up the coupling at roughly 20% on the allowable misalignment. For this coupling the installer need to seek to reach better than 0.020 parallel misalignment with the time of installation. This can enable for the supplemental misalignment that should happen since the consequence of equipment settle and common products wear.