The following is actually a sample application utilised to illustrate the typical system for choosing 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 employing a 225 horsepower electrical motor running at one,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electric motor features a 3-3/8 inch shaft using a 7/8 inch keyway as well as the compressor has a 92mm shaft having a 25mm keyway. The shaft separation is roughly seven inches in between shaft ends with some capability to alter the motor place. The shafts have a parallel misalignment/offset of roughly 1/32 of an inch.
Phase 1: The 1st phase is usually to figure out what coupling form is usually to be chosen for this application. Because the SU Form coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The next option can be to seem at an SX or DI Type coupling. The six bolt SX Type will accommodate the two parallel misalignment and the defined shaft separation. The size might be determined from the choice torque along with the shaft diameters.
Stage 2: Following, determine the application torque and apply the service component to calculate the variety 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 during 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 Service Component = Selection Torque
twelve,331 in-lbs x three.0 = 36,993 in-lbs
Step 3: Use the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, a lot more than adequate to take care of the variety torque calculated in stage two. The SX202-6, however, won’t support the 92mm shaft dimension. 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, pretty near to the application?¡¥s desired seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be excessive, on the other hand, the coupling dimension is critical to deal with the bore dimension.
Step 4: The SX228-6 coupling is rated for any optimum unbalanced velocity of 3,400 RPM, over enough to help the application velocity of one,150 RPM.
Phase five: To determine if your coupling will deal with the parallel misalignment, make use of 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 in the table on page 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), as a result this coupling can accommodate the parallel misalignment.
Note: It can be usually advisable to make an effort to install the coupling at approximately 20% of the allowable misalignment. For this coupling the installer should try to achieve superior than 0.020 parallel misalignment on the time of set up. This may let to the supplemental misalignment that will occur since the outcome of tools settle and basic equipment dress in.