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HOW IT WORKS |
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The CDB1621A is
spring applied and
electrically
released. When power
is turned off, the
torque spring
assembly pushes the
armature (#1) away
from the magnetic
body (#2). This
movement spreads the
arms out. The
caliper arms
articulate about
pivot points (#3)
forcing the pusher
plates to press on
the friction pucks.
Friction pucks (#4)
are held in machined
pockets in the
base's tower (#5).
As the pusher plates
(#6) exert a
squeezing force, the
pucks pinch the
disc. The resulting
torque reaction load
is directly
transmitted from the
pucks to the base's
tower.
The caliper arms do
not carry the torque
reaction load. This
allows them to
easily accommodate
the axial movement
of the DC motor thus
avoiding drag
problems that are
common to directly
applied caliper disc
brakes on hoists.
When power is
applied, the
armature is
attracted to the
magnetic body thus
collapsing the
torque spring. This
allows the caliper
arms to open thereby
releasing the disc.
 The
simple and rugged
design makes the new
CDB1621A well suited
for North American
steel mills.
There are four major
components to the
brake: coil, arms,
base, and friction
pucks.
The arms, base, and
friction pucks are
similar to PT Tech's
other CDB brakes,
but the coil is
entirely new. It
greatly simplifies
the design and
reduces the total
number of parts.
The coil is potted
into a magnetic
body. Coils are
available to operate
in series with DC
mill motors or in
shunt circuits. The
size and shape of
the coil/magnetic
body was designed
using sophisticated
computer software.
The software
optimizes the flux
density without
causing a heat
problem.
The coil/magnetic
body is connected to
the base on two
steel rods. This
allows it to
correctly position
itself and the arms
when accommodating
axial motor
movement. On top of
the magnetic body is
an armature gap
indicator and a
lifting lug. When
the indicator has
recessed 1/16," the
brake requires
adjusting. Adjusting
for wear is a two
minute job.
The lifting hole is
positioned to
provide a balanced
brake assembly. This
helps to make
installation easy.
There is a friction
puck wear adjusting
bolt on one side and
a torque adjusting
bolt on the other.
The wear adjuster
bolt has a hex head
requiring a 12"
adjustable wrench.
The torque adjusting
bolt is a button
head requiring a
3/8" Allen wrench.
Having different
types of bolts helps
to eliminate
mistakes when making
adjustments.
The patented slotted
base allows for ease
of installation and
removal. Like PT
Tech's other CDB
brakes, the base's
tower has machined
pockets to hold the
friction pucks.
During actuation the
tower takes the
reaction load
allowing the arms to
move freely to
accommodate axial
motor movement.
The friction pucks
are the same as used
in the CDB2329
(replaces a 23" drum
brake). Instead of
using six pucks like
the CDB2329, the
CDB1621A uses only
two pucks. A set of
pucks weighs 4½ lbs.
Replacing worn
friction material
takes less than 10
minutes. |
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APPLICATION
ASSISTANCE |
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 PT Tech has been
analyzing and
solving shockload
problems for heavy
industry since 1980.
Our application
engineers regularly
visit mills to
better appreciate
the problems that
plant engineers and
maintenance people
face when trying to
solve a shockload
problem.
In addition, PT
Tech's application
engineers have two
unique tools to
assist you. First,
our test stands can
simulate the inertia
shockload up to that
of a #820 DC mill
motor in the attempt
to better understand
how a torque limiter
will perform in your
application.
Second, using
thousands of test
results, PT Tech has
developed a
computerized
selection program
that quickly
determines the best
solution to your
shockload problem. |
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FIELD SERVICE |
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 The
people at PT Tech
who build our disc
brakes also go into
the field to service
them when needed. PT
Tech supports its
commitment to
excellent field
service with a large
inventory of parts
and a 24-hour
emergency service
hotline.
If you need us call
800-717-4358. |
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WHEN CONVERTING |
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The CDB1621A
directly replaces a
16" drum brake. It
has the same
mounting footprint
and torque capacity
as a 16" drum brake.
When converting, it
is critical that the
disc's centerline is
in the same position
as the drum's
centerline. (see
sketch) *
If the installation
conforms to AISE's
dimensional standard
for DC mill motors,
then when ordering
all that is required
is the DC mill motor
number and existing
electrical coil
specifications. In
all other
installations,
please provide a
drawing of the
existing brake
wheel.
Single-acting
caliper disc brakes
impose a bending
moment. Shafting
should be reviewed
prior to
installation.
Consult PT Tech.
In most cases, PT
Tech can suggest
mounting adaptations
for non-standard
drum brakes. Consult
PT Tech. |
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