My machine design textbook states that the fulcrum pin of a band brake during braking is subjected to a double shear. How do you say it is subjected to a double shear and not to a single one. By double shear the textbook means:
Double shear stress = 2 * shear stress

  • 2
    $\begingroup$ A diagram would help... $\endgroup$
    – Solar Mike
    Apr 23 '18 at 20:32
  • $\begingroup$ i guess the pin carries both the direct lever load and the band load. (VTC as unclear.) $\endgroup$
    – agentp
    Apr 24 '18 at 11:52
  • $\begingroup$ band brake or brand break?? A brake is a device for stoping. A break is a fracture $\endgroup$
    – Fred
    Apr 25 '18 at 4:07
  • $\begingroup$ @fred Spelling mistake sorry.It's brake not break. I've corrected the spelling in the question $\endgroup$
    – Xlam
    Apr 25 '18 at 15:22

From the image you should see that the pin on the left has two "lines" of shear stress while the one on the right only one, bending is of course an issue.

enter image description here

  • $\begingroup$ One thing that should be noted which I think OP is misunderstanding is that the shear force at each shear plane is half the perpendicular force (theoretically anyway). From OP's question it seems that he/she thinks it is double; or perhaps the question is just asked a bit strangely. $\endgroup$
    – ChP
    Apr 26 '18 at 11:41

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