The next is actually a sample application made use of to illustrate the regular process for deciding on 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:
An organization features a compressor application making use of a 225 horsepower electrical motor working 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 and the compressor has a 92mm shaft by using a 25mm keyway. The shaft separation is roughly seven inches in between shaft ends with some capacity to change the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Phase one: The first stage is to identify what coupling style is to be chosen for this application. Because the SU Type coupling only supports
just one flex plane, it can only accommodate angular and axial misalignment, but not parallel misalignment. The following selection might be to look at an SX or DI Variety coupling. The 6 bolt SX Type will accommodate both parallel misalignment and the defined shaft separation. The dimension are going to be established through the assortment torque as well as the shaft diameters.
Stage two: Subsequent, calculate the application torque and apply the services issue to determine the assortment torque.The formula applied to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging while in 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 = Selection Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Step three: Utilize the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over ample to handle the choice torque calculated in phase 2. The SX202-6, having said that, will not help the 92mm shaft size. The subsequent more substantial dimension coupling, the SX228-6, will support the 92mm shaft dimension and also the shaft separation dimension (BSE) is six.88 inches, very close to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may well seem to be excessive, nevertheless, the coupling size is important to manage the bore size.
Step four: The SX228-6 coupling is rated for a optimum unbalanced pace of 3,400 RPM, more than ample to help the application velocity of one,150 RPM.
Phase five: To find out when the coupling will take care of the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x the distance involving disc packs or ??S?¡¥ dimension in the table on webpage D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The maximum offset for that application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It is normally recommended to attempt to set up the coupling at approximately 20% with the allowable misalignment. For this coupling the installer really should attempt to accomplish greater than 0.020 parallel misalignment at the time of set up. This will let for that extra misalignment that should come about since the result of equipment settle and basic equipment put on.