In jest, the ERK is a "4 bar" device
https://www.youtube.com/watch?v=Vh8r_Cpfb8Q
http://bdml.stanford.edu/twiki.../Rise/LegDesign.html
this provides a non linear output of the MC as the input pedal is depressed.
as stated, if linear levers were used, to reduce the amount of force the pedal needs to be pushed, make the lever longer and increase the pedal travel.
the nonlinear response of the ERK has the long lever, easier to push when the clutch is fully depressed. HOWEVER, the initial couple inches of the clutch are actually with a shorter lever and thus harder to press. But at this initial depression, the only force that needs to be overcomed is taking out the clearance for the ToB and depressing the clutch arms a little.
the green straight line marked with the 5:1 slope is the pedal to MC withOUT the effort reduction.
the red curved line marked with the 7:1 slope is WITH the effort reduction. the 7:1 slope line is between the pedal travel of 3" to 8". this was to show that at the pedal hold down, the pedal force is reduced 5/7 (~70%). BUT the pedal does need to travel more to move the MC (and slave). to prevent the pedal travel from getting way excessive, the effort reduction linkage causes the initial depressing of the clutch to stroke the MC faster for the first couple inches. This does mean it will take more pedal force than original for these few inches, However, this is the ToB free travel and just compressing the fingers so not much force is needed.
does this make sense
Side story, It was just last year when another discussion of this linkage got me interested in exactly how it works and how much improvement it makes. while I hadn't model 4 bar linkage since my school days, I think I got my equations fairly close. Now the bad part...during your discussion the fact the one piece could be put in backwards, I went back and tried to write the equations to see how much differance it makes...I was dumbfounded! I can't understand a thing I did a year ago
