Slovak Shipping and Ports JSC
The crane is located in Bratislava, Slovakia, on the Danube River. It has a capacity of 560 tons.
The centerpiece of the Charleston Industrial District will be a water
to rail transfer. The loads will be moved with a large gantry crane.
My model will be very similar to the crane at Bratislava, in Slovakia.
The requirements are as follows:
The crane is located in Bratislava, Slovakia, on the Danube River. It has a capacity of 560 tons.
This crane is actually two cranes, that can be joined together to
lift a maximum of 560 tons.
The following photos were sent to me by Ivan Rojnica. They clearly
show how the two cranes work in concert, with a single spreader bar.
Port Area Drawing
Once I settled on modeling the crane at Bratislava, I needed a drawing to scale the crane, and the dock area. The water area had to be big enough to hold both the barge and tow boat made by Custom Model Railroads. The barge is 90 scale feet long and the tow boat is about 60 feet long. The largest schnabel car, CEBX 800, with load must fit under the crane.
3D Printed Hooks
The gantry crane will need at least two hooks. I had been
looking for some hooks for a while, when Patrick (another
Southern Railway modeler from Beaufort, S.C.) pointed me to an
O Scale hook on EBay. This hook was perfect for my HO Scale
needs. But I will need more than one, and could not find any
more.
I decided to try and make these with 3D printing. Opened SketchUp
a free 3D CAD tool. I searched their library for a crane hook,
and found one that looked like it would work, downloaded it,
and then scaled it down to HO scale. The completed file was
uploaded to Shapeways.
About three weeks later, the hooks show up. They were not the
correct size. Opened up the SketchUp file, and I had scaled it
in mm, when I was thinking/designing in inches. After fixed
the sizing, the updated file was uploaded back to Shapeways.
Another three week wait, and the new hooks arrive. Perfect,
just over 1 inch wide!
The right most photo below shows the first try, which turns
out to be too small. Next is the correctly sized one, followed
by the one purchased from EBay.
The crane trolley
I have started working on the trolley. The size of it is
based on the servo that will be used to power the lift. This
one servo will control two spools and two sets of pulleys. The
servo will connect to the lift spools via a chain and
sprocket. The servo has been modified to rotate continuously.
Did not quite finish, I ran out of brass tubing. I will have
to take more photos later, when the two sides are connected. I
need to get a smaller gear that will control the side to side
movement. This gear size will control the size of the
structure that connects the two sides.
About 40 pulleys will be needed for the crane and the two
sheaves. These are made from black sheet styrene from
Evergreen Scale Models, and their construction is covered in
the 2012 blog.
I am not happy with the width of the trolley's body. I am
planning to go back and build the second version, where the
servo is not in the body.
In planning for the crane's trolley, I have the
following requirements. It needs to have two hooks that
lift, and it needs to move side to side.
The first version has two servos motors for lifting the
hooks. The spools are connected to the servos with
sprocket and chain.
The second version has one servo motor that is connected
to both spools with sprocket and chain.
The third version moves the servo motor into the trolley
body. This is the version that I am going to build.
The last drawing shows how a second servo motor will be
used to move the trolley back and forth.
Motorizing the Gantry Crane
The gantry crane needs to move the length of the dock, but very slowly. I have thought of many ways to move the crane. I finally decided upon coupling nut running down a threaded rod. A friend connected me with Al (the welder from South San Francisco), who welded the nail onto the nut. I modified a RC Servo to rotate continuously. When mounted on some hardware from Servo City, it appears to be what I need. But when the servo is connected up to a battery, there is a fair amount of wobble. I will need to keep looking for a new slow speed motor.
Linear Drive - version 2
I have now resolved the wobble with a new motor from Servo City. The travel on this version is very smooth. I can control this one with a DCC controller.
