The next is often a sample application made use of to illustrate the conventional course of action for choosing 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 has a compressor application working with a 225 horsepower electric motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor includes a 3-3/8 inch shaft which has a 7/8 inch keyway plus the compressor features a 92mm shaft which has a 25mm keyway. The shaft separation is roughly seven inches concerning shaft ends with some potential to change the motor area. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Phase one: The 1st step is to establish what coupling style is always to be chosen for this application. Since the SU Form coupling only supports
just one flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following selection can be to seem at an SX or DI Form coupling. The 6 bolt SX Variety will accommodate the two parallel misalignment as well as the defined shaft separation. The dimension is going to be determined by the selection torque and also the shaft diameters.
Step 2: Next, determine the application torque and apply the service element to determine the assortment 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 within 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 Issue = Choice Torque
12,331 in-lbs x 3.0 = 36,993 in-lbs
Stage 3: Use the SX coupling tables and note that the SX 202-6 is rated at forty,700 in-lbs, more than sufficient to handle the assortment torque calculated in step two. The SX202-6, on the other hand, will not help the 92mm shaft size. The subsequent larger dimension coupling, the SX228-6, will support the 92mm shaft size and the shaft separation dimension (BSE) is 6.88 inches, really near to the application?¡¥s preferred seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, however, the coupling size is important to manage the bore dimension.
Step 4: The SX228-6 coupling is rated to get a highest unbalanced speed of three,400 RPM, a lot more than ample to help the application pace of one,150 RPM.
Stage five: To find out if the coupling will handle the parallel misalignment, use the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance among disc packs or ??S?¡¥ dimension from your table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The maximum offset for the application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It really is often encouraged to make an effort to install the coupling at approximately 20% with the allowable misalignment. For this coupling the installer must try and achieve better than 0.020 parallel misalignment on the time of set up. This will enable for that added misalignment that should happen since the outcome of tools settle and common products put on.