Techniques In Deciding on A Disc Coupling

The next is often a sample application made use of to illustrate the typical process for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
An organization includes a compressor application using a 225 horsepower electrical motor working at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor includes a 3-3/8 inch shaft by using a 7/8 inch keyway as well as the compressor includes a 92mm shaft having a 25mm keyway. The shaft separation is approximately seven inches among shaft ends with some skill to alter the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Phase one: The first step is always to identify what coupling sort is always to be chosen for this application. Because the SU Variety coupling only supports
just one flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The following decision can be to search at an SX or DI Kind coupling. The six bolt SX Style will accommodate both parallel misalignment along with the defined shaft separation. The dimension will probably be established by the selection torque and the shaft diameters.
Step two: Following, determine the application torque and apply the services issue to determine the selection torque.The formula used to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging during the numbers in the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Services Aspect = Assortment Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Phase 3: Use the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, more than ample to manage the selection torque calculated in stage two. The SX202-6, however, is not going to support the 92mm shaft dimension. The subsequent bigger dimension coupling, the SX228-6, will support the 92mm shaft size as well as the shaft separation dimension (BSE) is 6.88 inches, incredibly close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, nevertheless, the coupling dimension is critical to manage the bore size.
Phase four: The SX228-6 coupling is rated to get a maximum unbalanced pace of three,400 RPM, in excess of adequate to support the application pace of 1,150 RPM.
Stage five: To find out if the coupling will handle the parallel misalignment, utilize the trig function of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension in the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset to the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It really is generally suggested to make an effort to set up the coupling at approximately 20% from the allowable misalignment. For this coupling the installer must seek to reach greater than 0.020 parallel misalignment on the time of set up. This may make it possible for for your supplemental misalignment which will arise as the outcome of gear settle and basic gear dress in.