Statics Problem 5-73: Equilibrium of a Rigid Body with three Journal Bearing Supports

Statics Practice Problem with three journal bearings. Example of equilibrium of a rigid body with journal bearing supports. Journal bearings apply both force and moment reactions but if they are aligned, they only apply force reactions. Whenever there are journal bearing supports, equations are coupled, so we have to solve six equations simultaneously to find our six unknowns.

[@johndo7003]

Thank you for this video! I was wondering whether we could choose the origin as the point to calculate the moment? I've tried it with the origin and it seems like I get the wrong answers :(

[@engineeringvision]

Yes, you can choose any point for moment calculation. As we are in equilibrium, the moment is zero about any point.

[@driesvanranst3440]

Thanks!

[@engineeringvision]

You are welcome! Which school are you studying at?

[@driesvanranst3440]

KU Leuven in Belgium

[@anthonygutierrez393]

Wouldn't it be 2j for the AD position

[@engineeringvision]

Yes, I corrected it later on in the video, look at minute 9:30

[@GenDrag1]

For future travelers:
Ax, Az, By, Bz, Cx, and Cy can be found by
-using Bz + 2Cx = 0 , turn it into 2Bz = -4Cx, and replace 2Bz in i=0
-using 200 + By + Cy = 0 from sigma-Fy = 0, turn it into -By = 200 + Cy, and plug it into k=0 equation for -By
- set equal to each other: -1385.6 - 4Cx - 2Cy = 0 AND your =984 -4Cx -1.5Cy = 0
-Now you have Cy
-Solve for By
-Solve for Bz
-Solve for Cx
-Solve for Ax and Az, just because we took the moment about A doesn't mean we can forget about them :p
and that's it
saved you what was for me 3hrs and 41 minute
good luck traveler

[@engineeringvision]

To save time, use MATLAB or EXCEL if you have access to them to solve set of equations