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The crane stands where it was
constructed.
The two jibs
have been held in place
for eight months straight.
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The crane
at NALUG's
layout at the 2001
Great Edmonton Train Show (GETS).
Here
is another shot where the illuminated
floodlights and red aircraft warning lights are
visible.
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This is what the average Technic fig would
see.
At Technic scale (6':3.5"), the crane would be
about 140' tall.
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Here's a view from
the counterweight jib.
The opposite view
illustrates the inverted
triangular cross-section of the main jib. This
was challenging to accomplish using classic
Technic parts.
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The design of the top
rotating portion of the
tower was inspired by the construction of lower
fixed portion. With one exception, all of the
horizontal beams have the same vertical spacing.
However, the horizontal beams in the top portion
are upside down to fascilitate connection of the
jibs. The regularly-spaced inverted beams can be
seen in this close-up.
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The turntable
supports the entire weight of the
top portion. One 9V geared motor drives the
8-toothed gear that can turn the unlubricated
turntable. The center of the turntable remains
clear for the crane operator to pass through.
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The sturdy crane tower is
built in 16-stud
sections.
Only four 1x16 Technic beams support
the entire crane's weight, as shown in this
LDRAW model
(Building steps pics:
1,
2,
3,
6,
7).
Here
is a closer look of the half-beam
section connectors, the bracing, and the
turntable support.
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The operator's cab was
built in the rotating
portion of the tower. The operator's seat is
partially visible behind the left vertical 1x16
beam. The vertical 1x16 beams comply with the
specifications of the 16-stud tower section, part
of which is visible at the bottom of this
shot. The
worm gear is mounted on hinge plates so that
it can be moved aside to permit weathervaning.
In life-sized cranes, the jibs are able to spin
freely in high winds to prevent against damage
or collapse. In this crane, weathervaning is useful
if manual spining of the jibs is necessary.
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The cab was created
in the style of classic
Technic models, ensuring that Technic figure
would fit into the enclosure. It utilizes studless
beams with bends to form the angled frame. The
plate that serves as the floor is inverted due to the
downward-facing studs of the horizontal structural
beams.
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The turntable motor assembly
is concealed
behind the operator's cab.
Very little of the
mechanism is visible when the cab is viewed
from the side. When viewed from
the rear, the
entire mechanism is intentionally visible.
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The trolley is pulled
along the main jib on a
186-stud track. The track is actually inverted
2x16 black plates mounted to double yellow
beams with 1xn plates and 1x2 center-studded
tiles.
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The hook was designed for
both form and
function. A metal Technic hook with a single
pulley would not conform with the scale of the
crane, so a double-pulley mechanism was added.
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The main jib is anchored
to the tower with
fixed beams and with cables. The entire jib is
visible in this shot.
The trolley moves
along the entire length of the main jib.
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The main jib uses axles
and angle connectors
to achieve a form that resembles reality.
Each 16-stud jib section contains four supporting
#10 axles. Real-life cranes feature jibs with
inverted or non-inverted triangular cross sections.
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The main jib connects
to the tower
by stepping the inverted beams from the track
until they meet with the vertical beams of the
tower. Above this is a support structure con-
sisting of truss axles connected in the same way
as the rest of the jib except that the shorter right
axles connect to the sloping axles that brace
the top beams of the jib.
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A free-running trolley pulley
is attached to the
extreme end of the jib. The construction the
bracing of this pulley was constrained by weight
and appearance. The red elastics provide tension
for the hook cable since the anchor tends to move
outward. In addition, connection of the angled
truss axle at the end of the jib was nearby.
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This view is directed along the top of the
main jib toward the
tower. The upper beams
and axles of ten 16-stud jib sections are visible
in this shot.
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The view from the bottom end of the
main jib.
The trolley track, which is a series of black
2x16 plates, can be seen on the jib. The
operator's cab is
visible at the far end of
the main jib.
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The counterweight jib
was built to hold the
counterweight, two motors, a 9V battery box, and
the RCX. A simple NQC program
illustrates how a
sequence of commands can be stored. A LEGO remote
control provides manual control of all 3 crane
motors. The counterweight jib frame is built in
16-stud sections. Sections connect to each other
with bracing that is primarily achieved with short
yellow beams.
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The counterweight jib
features yellow railings
that surround the entire upper surface. In
this shot,
the counterweight and utility crane are visible.
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The utility crane
is powered by a micromotor
and is manully rotated. The 9V battery
box supplies power to both the aircraft
warning lights and this micromotor.
The end of the
counterweight jib has
adequate work space protected by railings.
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The utility crane is controlled by the polarity
switch shown here. The 9V
power supply is
switched on by pushing up on the 1x4 yellow
plate in the center of the image. This turns
on the aircraft warning lights. If the polarity
switch controls the power and direction to the
utility crane motor.
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The RCX is mounted
in the counterweight jib
facing the ground. It is located between the
hook and trolley motors. The RCX and the LEGO
remote control allow manual operation, while a
short NQC program provides
some automation.
The battery pack of the RCX is accessible from
above.
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The trolley motor assembly.
The 9V geared
motor is stepped down so that the trolley moves
consistently. The crown gear is actually the axis
of a sub-assembly that is attached at the tops with
elastics. This enables the trolley cable to be
tensioned after the cable loop is constructed.
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In this image, two pulleys
direct the hook cable
around the trolley pulley assembly. The
pulley in the middle guides the trolley cable,
which returns through the hole in the yellow
structural beam. Here
is another view
of the cable system.
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The counterweight jib is
attached to the
tower at the same elevation as the main jib.
Grill plates in the counterweight jib serve as
platforms for servicing, assembly and dis-
assembly. Wires to the aircraft warning lights
and the turntable motor are visible.
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