[CAUT] Digest, Vol 1103, Issue 85 Moving Wippen Rail

[Richard Brekne]

All of which fits very nicely with most of whats been published on the 
subject before, and with the basic precept that whippen spread should be 
set from the perspective of geometric sense.  I would suspect that if 
someone actually measured a gain in touchweight because of a whippen 
move... then it would be because the move was actually a corrective of a 
bad geometric condition.

That said... I'm still pondering the position of the jack center being 
the definitor of the second arm instead of the jack top... and how that 
evt. plays in in all this.

Cheers
RicB


    I was in error a few posts back thinking that the repetition lever
    acted as a second class lever within the compound leverage
    of the wippen. The knuckle would have to be situated between
    the flange center and the capstan for that to happen.
    Like it or not a wippen is a third class lever, period.

    Moving the rail changes both the load and lift measurements in like
    manner
    thus making any ratio change negligible. To change the Wippen Ratio, one
    has to either move the stack (which alters WR by altering the input
    arm only);
    move the capstan (which alters both Key Ratio and WR);
    or move the knuckle (which alters Shank Ratio and Wippen Ratio).

    A change in ratio comes about by altering either lift OR load not
    both simultaneously
    unless you move the capstan forwards and the knuckle further out on
    the shank thus
    increasing the input arm and decreasing the output arm. Moving the
    rail back
    increases both input and output.

    Any gain in touchweight while moving the wippen rail is a product of
    aligning to
    a line of convergence not ratio change.  If ratio were the case then
    the further back
    you move the rail beyond convergence, the better the touchweight
    still becomes.
    -- 

    Regards,

    Jon Page