January 26, 2021

The next is usually a sample application employed to illustrate the standard approach for picking out 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 applying a 225 horsepower electrical motor operating at 1,150 RPM to drive a three cylinder multi stage reciprocating air compressor. The electrical motor has a 3-3/8 inch shaft with a 7/8 inch keyway and also the compressor includes a 92mm shaft using a 25mm keyway. The shaft separation is roughly 7 inches among shaft ends with some capacity to modify the motor spot. The shafts have a parallel misalignment/offset of approximately 1/32 of an inch.
Stage one: The very first phase is usually to decide what coupling variety should be to be chosen for this application. Because the SU Kind coupling only supports
a single flex plane, it might only accommodate angular and axial misalignment, but not parallel misalignment. The subsequent option will be to look at an SX or DI Sort coupling. The 6 bolt SX Kind will accommodate the two parallel misalignment along with the defined shaft separation. The size will likely be established from the selection torque along with the shaft diameters.
Phase 2: Next, calculate the application torque and apply the service issue to calculate the selection torque.The formula utilized to calculate torque is as follows:
Application Torque ( in¡§Clb ) = ( HP x 63025 )/RPM
or Nm = ( KW x 9550)/RPM
Plugging within the numbers through the application description:
Application Torque ( in-lbs ) =(HP x 63025)/RPM = (225 x 63025)/1150 = 12,331 in-lbs
Application Torque x Services Component = Choice Torque
12,331 in-lbs x three.0 = 36,993 in-lbs
Stage three: Utilize the SX coupling tables and note the SX 202-6 is rated at forty,700 in-lbs, over sufficient to manage the selection torque calculated in stage 2. The SX202-6, on the other hand, is not going to help the 92mm shaft dimension. The next bigger size coupling, the SX228-6, will help the 92mm shaft dimension plus the shaft separation dimension (BSE) is 6.88 inches, quite near to the application?¡¥s sought after 7 inch separation. The SX228-6 is rated at 62,000 in-lbs which may possibly appear to be extreme, nevertheless, the coupling dimension is necessary to deal with the bore dimension.
Stage four: The SX228-6 coupling is rated to get a highest unbalanced speed of three,400 RPM, in excess of adequate to support the application velocity of 1,150 RPM.
Phase 5: To determine if the coupling will deal with the parallel misalignment, make use of the trig perform of tan 1?? = offset allowed for 1 inch = 0.0174
Multiply the 0.0174 x the distance in between disc packs or ??S?¡¥ dimension from your table on web page D-13, or 5.50 inches.
The allowable parallel offset is 0.0174 x 5.50 = 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 truly is usually proposed to try to install the coupling at roughly 20% of the allowable misalignment. For this coupling the installer need to endeavor to reach far better than 0.020 parallel misalignment on the time of set up. This will allow for the supplemental misalignment that can arise because the outcome of products settle and standard gear dress in.