What is the Crushing Force of a Concrete Crusher?

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Discussion Overview

The discussion revolves around determining the crushing force of a concrete crusher, specifically focusing on the mechanics involved, including the forces exerted by the cylinder and the levers used in the crushing process. Participants explore concepts from physics, such as Newton's laws and lever principles, in the context of this application.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether the crushing force on the concrete should be calculated as 2*Ft or just Ft.
  • Another participant inquires about the force exerted by the cylinder on each jaw, asking if it should be Fc/2 or Fc.
  • A participant suggests considering action and reaction principles and Newton's First Law, as well as the principles of levers.
  • One participant reflects on their initial thought that the cylinder would exert only half of its force on each lever, but later revises this thought process, proposing a calculation involving the force Fc and angle theta.
  • Another participant confirms the revised calculation, stating that the moments applied at the tips of the levers lead to the crushing force Ft, equating it to Fcrush.
  • A later reply mentions the existence of patents related to concrete crushing tongs, adding context to the discussion.

Areas of Agreement / Disagreement

Participants express differing views on the calculation of forces involved in the crushing process, indicating that multiple competing models and interpretations remain unresolved.

Contextual Notes

There are unresolved assumptions regarding the definitions of forces and the specific mechanics of the concrete crusher, as well as the dependence on the angle theta and other parameters in the calculations.

nofx1981
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Hi guys,
I need to figure out the crushing force of a concrete crusher. Here's a pic to help illustrate:

CrackerQ.jpg


I have 2 questions:
1) Would the crushing force on the concrete be 2*Ft or only Ft
and
2) Would the force exerted by the cylinder on each jaw be Fc/2 or Fc as shown.

Thanks for you help!
 
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Hi, nofx1981. Is this for a school assignment?
 
Think about action and reaction and Newtons First Law.
Also think about the principles of levers.
 
Last edited:
Hi, nofx1981. Is this for a school assignment?

No, this isn't for school. I've finished school a number of years ago.

Think about action and reaction and Newtons First Law.
Also think about the principles of levers.

Yes, I have been thinking of of Newton's 1st law and levers and such

My first thought was that the cylinder would exert only half of it's force on each lever and that the crushing force would be the sum of forces at the tips. But now I'm thinking that isn't right.

This is my new train of thought. So the cylinder exerts a force Fc=P*A at an angle of theta on each lever. So there is a moment about O of Fc*sin([tex]\theta[/tex])*dc for each lever. These moments will apply a force at the tip of each lever Ft=Fc*sin([tex]\theta[/tex])*dc/dt and this is your crushing force, right? Ft=Fcrush?

It's been a while since I've done this kind of stuff, would really just like some confirmation...

Thanks for the help!
 
This is my new train of thought. So the cylinder exerts a force Fc=P*A at an angle of theta on each lever. So there is a moment about O of Fc*sin()*dc for each lever. These moments will apply a force at the tip of each lever Ft=Fc*sin()*dc/dt and this is your crushing force, right? Ft=Fcrush?

This is correct. Otherwise the concrete block would fly off somewhere.
And you worked it out for yourself!

I note Google lists several patents on concrete crushing tongs.
 

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