How to calculate (mechanical) clutch forces

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Discussion Overview

The discussion revolves around calculating the forces involved in a mechanical clutch system, particularly in relation to a clutch cable testing machine. Participants explore the relationship between the force applied to the clutch pedal and the resulting force on the clutch mechanism, considering mechanical advantages and the behavior of the system during operation.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks to understand the relationship between the force applied to the clutch pedal and the force exerted on the clutch, questioning if they are equal or if the clutch force is greater.
  • Another participant suggests using a load cell to measure the force on the clutch pedal to establish a baseline for adjustments.
  • A participant explains that the force on the clutch is influenced by the mechanical advantage of the clutch arm lengths, proposing a formula to calculate the clutch cable force based on pedal force and arm lengths.
  • It is noted that the force measured in PSI will peak and then drop due to the characteristics of the diaphragm spring, affecting the resistance encountered during pedal operation.
  • A participant estimates that with a specific mechanical advantage ratio, the force on the clutch cable and subsequently on the throwout bearing can be calculated, suggesting a multiplication of forces based on the ratios involved.
  • There is a correction regarding the terminology used, clarifying the difference between "peak" and "peek" in the context of force measurements.

Areas of Agreement / Disagreement

Participants present multiple viewpoints regarding the calculations and mechanics involved, with no consensus reached on the exact forces or the best approach to measuring them. The discussion remains open with various hypotheses and methods proposed.

Contextual Notes

Participants rely on assumptions about mechanical advantage ratios and the behavior of the clutch system, which may vary based on specific designs and configurations. The discussion does not resolve the complexities involved in accurately measuring and calculating the forces.

kanibal
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Hello
i am working on a small clutch cable testing machine this machine can give the lifetime of clutch cable
i need some assistance to figure out how much forces i need to apply on this mechanism , and because the cable related directly in the clutch I'm asking if the force in the clutch in the same us what we give to the pedal example : if i push the pedal with 200 N how mach force is applied into release the clutch it is the same 200 N or more and why !
Automo74_ypagcc.jpg


this is the mechanism i made
 
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Simple solution is to attach a load cell to the clutch pedal and press it down slowly and release it slowly, it will give you force in PSI at its peek in both directions of travel. Just repeat till you have a base line and average it, then adjust the machine accordingly.
 
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kanibal said:
if i push the pedal with 200 N how mach force is applied into release the clutch it is the same 200 N or more and why !

With regard to the above question the force on the clutch is first increased at the clutch pedal assembly. The force you place on the pedal is multiplied by the ratio of the clutch arm length between the pivot and the pedal and the clutch arm length between the clutch cable connection and the pivot.
ie. F clutch cable = F foot x L foot pedal / L cable connection
Additionally, the actual force on the clutch may also be increased over the cable force by a similar design on the throwout fork between the clutch plate bearing contact point(s) and the clutch cable attachment point
 
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Its worth noting that the PSI will peek and then drop as the clutch pedal is pressed due to the (release point) on the diaphragm spring. I am assuming that "peek" is what you are looking for. When the throw-out Bearing is pressed against the diaphragm spring passed the middle point of travel it (breaks) and becomes easier to push once its passed that point due to less resistance in the spring.
 
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thank you both of you for the answer

How the machine would look like if I asked you making this machine if possible with a simplified drawing to make it easier to understand
 
Looking at your drawing, and making some rough guesses.

If the ratio of the distance from the clutch pedal 'pad' to the cable attachment point is 3:1, that will be the mechanical advantage you have on the cable, so 200N of force on the pedal will be 600N of force on the cable.. Then once more you look at the mechanical advantage the cable has on the throwout bearing.. Most designs similar to what you show have about a 3:1 ratio again, so the 600N of force on the cable is multiplied to 1800N

@qjonesy I think you mean "peak" (Maximum) not "peek" (take a look at)
 

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