The following is a sample application used to illustrate the standard course of action for choosing a Disc coupling. Any resemblance to any present company?¡¥s application is neither intentional nor meant to resemble that company?¡¥s actual application.
Sample Application:
A company features a compressor application utilizing a 225 horsepower electrical motor running at one,150 RPM to drive a 3 cylinder multi stage reciprocating air compressor. The electric motor has a 3-3/8 inch shaft that has a 7/8 inch keyway as well as the compressor has a 92mm shaft by using a 25mm keyway. The shaft separation is approximately 7 inches among shaft ends with some capability to change the motor place. The shafts possess a parallel misalignment/offset of roughly 1/32 of an inch.
Stage 1: The very first step would be to ascertain what coupling sort is always to be selected for this application. Because the SU Variety coupling only supports
a single flex plane, it may only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent choice might be to look at an SX or DI Kind coupling. The six bolt SX Style will accommodate the two parallel misalignment and the defined shaft separation. The size will probably be established by the choice torque as well as shaft diameters.
Step 2: Upcoming, determine the application torque and apply the support issue to determine the assortment torque.The formula employed to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging inside the numbers from the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Service Issue = Variety 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, over ample to manage the variety torque calculated in phase 2. The SX202-6, nonetheless, is not going to assistance the 92mm shaft size. The subsequent larger size coupling, the SX228-6, will help the 92mm shaft size plus the shaft separation dimension (BSE) is 6.88 inches, really near to the application?¡¥s wanted seven inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, nonetheless, the coupling dimension is necessary to handle the bore size.
Step four: The SX228-6 coupling is rated for any maximum unbalanced speed of 3,400 RPM, a lot more than adequate to support the application speed of one,150 RPM.
Step 5: To determine when the coupling will take care of the parallel misalignment, use the trig function of tan 1?? = offset permitted for 1 inch = 0.0174
Multiply the 0.0174 x the distance amongst disc packs or ??S?¡¥ dimension from your 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 that application is 1/32 inches (0.031), hence this coupling can accommodate the parallel misalignment.
Note: It is normally advised to try and set up the coupling at roughly 20% of your allowable misalignment. For this coupling the installer should really attempt to reach improved than 0.020 parallel misalignment at the time of installation. This will likely allow to the added misalignment that will happen because the result of gear settle and general gear dress in.