The following is really a sample application applied to illustrate the typical approach for choosing 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:
A company has a compressor application applying a 225 horsepower electric motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft with a 7/8 inch keyway and also the compressor has a 92mm shaft by using a 25mm keyway. The shaft separation is roughly seven inches amongst shaft ends with some capability to adjust the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Stage one: The very first step should be to identify what coupling sort is usually to be picked for this application. Since the SU Form coupling only supports
a single flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The next selection could be to look at an SX or DI Type coupling. The 6 bolt SX Sort will accommodate the two parallel misalignment as well as the defined shaft separation. The dimension might be established through the choice torque and also the shaft diameters.
Phase two: Upcoming, calculate the application torque and apply the service element to determine the choice 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 in the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = twelve,331 in-lbs
Application Torque x Services Element = Choice Torque
twelve,331 in-lbs x 3.0 = 36,993 in-lbs
Step 3: Utilize the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, greater than sufficient to manage the choice torque calculated in phase 2. The SX202-6, having said that, won’t assistance the 92mm shaft size. The subsequent greater size coupling, the SX228-6, will assistance the 92mm shaft dimension along with the shaft separation dimension (BSE) is six.88 inches, extremely close to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which might seem to be excessive, nonetheless, the coupling size is necessary to take care of the bore dimension.
Stage 4: The SX228-6 coupling is rated for any highest unbalanced speed of three,400 RPM, in excess of enough to support the application speed of 1,150 RPM.
Stage 5: To determine when the coupling will deal with the parallel misalignment, use the trig perform of tan 1?? = offset allowed for one inch = 0.0174
Multiply the 0.0174 x the distance concerning disc packs or ??S?¡¥ dimension in the table on page D-13, or five.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The utmost offset for that application is 1/32 inches (0.031), thus this coupling can accommodate the parallel misalignment.
Note: It is actually constantly advised to try and install the coupling at roughly 20% in the allowable misalignment. For this coupling the installer really should endeavor to realize greater than 0.020 parallel misalignment at the time of installation. This may make it possible for to the more misalignment that will arise since the consequence of equipment settle and basic products put on.