The next is actually a sample application made use of to illustrate the common procedure for selecting 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 includes a compressor application utilizing a 225 horsepower electric motor running at 1,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft by using a 7/8 inch keyway plus the compressor has a 92mm shaft that has a 25mm keyway. The shaft separation is roughly seven inches involving shaft ends with some capability to adjust the motor location. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Step one: The first stage is usually to establish what coupling form should be to be selected for this application. Because the SU Variety coupling only supports
just one flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent selection can be to look at an SX or DI Sort coupling. The six bolt SX Form will accommodate each parallel misalignment and the defined shaft separation. The size will likely be determined from the selection torque as well as shaft diameters.
Step two: Upcoming, determine the application torque and apply the service aspect to calculate 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 during the numbers from your application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Issue = Selection Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Make use of the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, over ample to take care of the choice torque calculated in phase 2. The SX202-6, however, will not assistance the 92mm shaft size. The following larger dimension coupling, the SX228-6, will assistance the 92mm shaft dimension as well as the shaft separation dimension (BSE) is six.88 inches, incredibly near to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which could appear to be extreme, on the other hand, the coupling size is necessary to take care of the bore dimension.
Stage four: The SX228-6 coupling is rated for any maximum unbalanced velocity of 3,400 RPM, a lot more than adequate to assistance the application velocity of 1,150 RPM.
Step 5: To determine when the coupling will handle the parallel misalignment, make use of 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 page D-13, or five.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), as a result this coupling can accommodate the parallel misalignment.
Note: It truly is normally encouraged to make an effort to set up the coupling at roughly 20% from the allowable misalignment. For this coupling the installer really should seek to achieve greater than 0.020 parallel misalignment at the time of set up. This will enable for that further misalignment that could take place since the end result of equipment settle and basic products wear.