is
lo cating
the
pin
whic
h
is
binding
the
most.
The
force
diagram
(Figure
5.5)
developed
in
c
hapter
5
suggests
a
fast
w
a
y
to
select
the
correct
pin
to
lift.
Assume
that
all
the
pins
could
b
e
characterized
b
y
the
same
force
diagram.
That
is,
assume
that
they
all
bind
at
once
and
that
they
all
encounter
the
same
friction.
Now
consider
the
eect
of
running
the
pick
o
v
er
all
the
pins
with
a
pressure
that
is
great
enough
to
o
v
ercome
the
spring
and
friction
forces
but
not
great
enough
to
ov
ercome
the
collision
force
of
the
key
pin
hitting
the
hull.
An
y
pressure
that
is
ab ov
e
the
at
p ortion
of
the
force
graph
and
b
elo
w
the
top
of
the
p
eak
will
work.
As
the
pic
k
passes
o
v
er
a
pin,
the
pin
will
rise
until
it
hits
the
h
ull,
but
it
will
not
enter
the
hull.
See
Figure
5.3.
The
collision
force
at
the
sheer
line
resists
the
pressure
of
the
pic
k,
so
the
pick
rides
ov
er
the
pin
without
pressing
it
into
the
hull.
If
the
prop
er
torque
is
b eing
applied,
the
plug
will
rotate
slightly
.
As
the
pick
leav
es
the
pin,
the
key
pin
will
fall
back
to
its
initial
p
osition,
but
the
driver
pin
will
catch
on
the
edge
of
the
plug
and
stay
ab ov
e
the
sheer
line.
See
gure
6.1.
In
theory
one
stroke
of
the
pick
ov
er
the
pins
will
cause
the
lo
c
k
to
op en.
In
practice,
at
most
one
or
tw
o
pins
will
set
during
a
single
strok
e
of
the
pic
k,
so
several
strokes
are
necessary
.
Basically
,
you
use
the
pick
to
scrub
bac
k
and
forth
o
v
er
the
pins
while
you
adjust
the
amoun
t
of
torque
on
the
plug.
The
exercises
in