Parallel
Misalignment
Parallel
misalignment
is
where
the
driver
and
driven
shafts
are
parallel
but
the
driver
and
driven
pulleys
on
these
shafts
lie
in
different
planes.
Angular
Misalignment
Angular
misalignment
is
where
the
driver
and
driven
shafts
are
not
parallel.
Resulting
in
uneven
loading
of
the
tensile
cords.
The
tensile
cords
on
the
high
tension
side
are
often
overloaded
which may
cause
edge
cord
failure
which
would
be
transmitted
across
the
width
of
the
belt.
This
misalignment
also
results
in
high
belt
tracking
forces
which
causes
excessive
belt
edge
wear,
Any
degree
of
misalignment
will
result
in
some
reduction
of
belt
life,
which is
not
accounted
for
in
the
normal
drive
design
procedure.
Misalignment
of timing
belt
drives
should
be
less
than
1/4° degree
or
1/16
per
foot
of
linear
distance.
A
simple
procedure
to
check
misalignment
(both
parallel
and
angular)
is
by
using
a
straightedge
(ruler)
to
check
alignment
as
the
above
illustration
shows.
The
straightedge
should
be
long
enough
to
span
the distance
between
the
two
outside
edges
of
the
pulley
faces.
Lay
the
ruler
across
the
face
of
the
two
pulleys,
if
the
two
pulley
faces
are
not
even
with
the
straightedge
than
you have
parallel
misalignment.
Another
possibility
with
using
the
straightedge
method
would
be
that
one
of
the
pulley
faces
would
lay
flush
with
the
straightedge
while
the
other
pulley
would
have
only
one edge
of
the
pulley
face
touching
the
straightedge.
In
this
scenario
an
angular
misalignment
would
be
represented.
This
process
should
then
be
reversed
using
the
opposite
pulley
as
a
starting
point
so that
the
total
effect
of
the
misalignment
is
taken
into
account.
Remember
to
account
for
differences
in
the
pulley
edge
thickness
dimension
and
also
the
degree
of
bend
on
the
pulley
flanges.
Another
procedure
for
checking
for
parallel
misalignment
would
be
to
accurately
measure
the
distance
between
the
shafts
at
three
points
along
the
shaft.
The
distance
between
the
shafts
should
be
the
same
at all
three
points.
Also
make
sure
that
the
shafts
are
rigidly
mounted.
Shafts
should
not
deflect
when
the
belt
is
tensioned.
A
non-rigid
mount
causes
variation
in
the
center
to
center
distances
resulting
in
belt
slack. This
belt
slack
could
lead
to
a
jumping
of
teeth
on
the
pulley
-
especially
under
starting
load
with
shaft
misalignment.
- Install
new
belt
Install
new
belt
over
sprockets.
Do
not
pry
or
use
force
- Pre-Tensioning/Final
Tensioning
Proper
tensioning
can
not
be
stressed
enough,
to
loose
of
tensioning
will
cause
the
belt
to
ratchet
(tooth
jumping),
while
to
tight
of
tensioning
will
possibly
cause
damage
to
the
bearings,
shafts and
other
drive
components
besides
dramatically
reducing
belt
life.
| Loose
belt
tensioning
acts
like
a
loosely-held
piece
of
string,
with
a
snapping
action
as
in
a
high
torque
situation
the
string
or
belt
will
break
because
the
added
stress
is
more than
the
belt
was
designed
to
take.
While
a
taut
string
or
belt
can
stand
a
strong
pull. |
 |
 |
Take
up
any
loose
slack
in
the
belt
by
adjusting
the
center
to
center
distance
between
the
two
pulleys.
Before
any
final
tensioning
is
to
be
applied
make
sure
that
the
belt
teeth are
fully
seated
in
the
tooth
grooves
on
both
pulleys.
Check
to
make
sure
that
belt
teeth
stay
seated
in
the
tooth
grooves
by
rotating
the
drive
system
by
hand.
After
the
pre-tensioning steps
are
completed
there
are
several
methods
for
verifying
proper
final
tensioning. |
