Measures In Deciding on A Disc Coupling

The next is often a sample application employed to illustrate the normal course of action for choosing a Disc coupling. Any resemblance to any current company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s real application.
Sample Application:
An organization has a compressor application employing a 225 horsepower electric motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electrical motor features a 3-3/8 inch shaft with a 7/8 inch keyway as well as the compressor has a 92mm shaft having a 25mm keyway. The shaft separation is approximately 7 inches amongst shaft ends with some capacity to change the motor area. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Step one: The 1st step is always to establish what coupling type will be to be picked for this application. Since the SU Sort coupling only supports
just one flex plane, it may possibly only accommodate angular and axial misalignment, but not parallel misalignment. The following preference would be to look at an SX or DI Type coupling. The six bolt SX Form will accommodate the two parallel misalignment plus the defined shaft separation. The dimension will probably be determined from the selection torque as well as the shaft diameters.
Stage two: Following, determine the application torque and apply the support factor to calculate the choice torque.The formula used to determine torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging from 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 Factor = Assortment Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Stage 3: Utilize the SX coupling tables and note that the SX 202-6 is rated at 40,700 in-lbs, in excess of enough to take care of the choice torque calculated in stage 2. The SX202-6, even so, is not going to 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, incredibly near to the application?¡¥s desired 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which might appear to be extreme, nevertheless, the coupling size is important to handle the bore size.
Stage 4: The SX228-6 coupling is rated for any greatest unbalanced velocity of three,400 RPM, in excess of adequate to help the application velocity of 1,150 RPM.
Phase five: To determine should the coupling will take care of the parallel misalignment, utilize the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension through the table on webpage D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x five.50 = 0.096 inches. The utmost offset for the application is 1/32 inches (0.031), consequently this coupling can accommodate the parallel misalignment.
Note: It is actually normally encouraged to endeavor to install the coupling at roughly 20% on the allowable misalignment. For this coupling the installer should try and achieve greater than 0.020 parallel misalignment with the time of installation. This will likely make it possible for for that additional misalignment that will take place as the outcome of tools settle and common tools dress in.