The next is really a sample application utilized to illustrate the normal procedure for deciding on a Disc coupling. Any resemblance to any existing company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization features a compressor application utilizing a 225 horsepower electrical motor operating at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft using a 7/8 inch keyway and the compressor includes a 92mm shaft using a 25mm keyway. The shaft separation is approximately 7 inches in between shaft ends with some means to modify the motor location. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage 1: The very first stage is usually to identify what coupling sort should be to be picked for this application. Because the SU Type coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent preference would be to appear at an SX or DI Type coupling. The six bolt SX Type will accommodate each parallel misalignment plus the defined shaft separation. The size will be established from the variety torque along with the shaft diameters.
Stage two: Subsequent, calculate the application torque and apply the services component to calculate the selection torque.The formula utilised to determine 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 = twelve,331 in-lbs
Application Torque x Service Factor = Assortment Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Phase 3: Make use of the SX coupling tables and note the SX 202-6 is rated at 40,700 in-lbs, over adequate to deal with the selection torque calculated in phase 2. The SX202-6, however, won’t support the 92mm shaft dimension. The following bigger dimension coupling, the SX228-6, will assistance the 92mm shaft dimension along with the shaft separation dimension (BSE) is six.88 inches, incredibly close to the application?¡¥s wanted 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may perhaps appear to be excessive, nonetheless, the coupling dimension is necessary to take care of the bore size.
Stage 4: The SX228-6 coupling is rated for a maximum unbalanced velocity of 3,400 RPM, more than sufficient to support the application velocity of one,150 RPM.
Phase five: To determine in the event the coupling will manage the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for one inch = 0.0174
Multiply the 0.0174 x 
the distance concerning disc packs or ??S?¡¥ dimension through the table on webpage D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 0.096 inches. The utmost offset for your application is 1/32 inches (0.031), therefore this coupling can accommodate the parallel misalignment.
Note: It can be generally suggested to endeavor to set up the coupling at roughly 20% of the allowable misalignment. For this coupling the installer really should seek to accomplish far better than 0.020 parallel misalignment at the time of installation. This may make it possible for for your supplemental misalignment that can arise as the end result of products settle and standard equipment dress in.
