Focusing on building the gantry crane.
May - Block and sheave
In 2012, I built the sheaves, or pulleys. Now that I have the
hooks, they all need to be assembled together into the block. The
blocks shown were found at the Carolina
Heavy Lift site, at the port in North Charleston, S.C.
Block at Carolina Heavy Lift
Another block
April - Spreader bar
I have started working on the spreader bar that will be used to
lift the loads onto the Schnabel or flat cars. I found a great
photo of a two level spreader bar that was used at the General
Electric plant in Pittsfield, Mass. GE manufactured transformers
at Pittsfield. The photo was found on a IEEE
website. The spreader bars at the Carolina Inland Port wil be
based on these. Another example that may be used is the new 450
ton Demag crane at Seimens Westinghouse, here is the source
of the photo.
The other photos are of the 500 ton spreader bar used on the
Carolina Heavy Lift floating crane.
The first version slipped in the clamps and turned out not being
square.
Spreader bar at GE Pittsfield
Siemens Westinghouse at Charlotte
Carolina Heavy Lift spreader bar
Carolina Heavy Lift crane
March - 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.
View from Sketchup
My collection of hooks
February - 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.
Overhead view of the trolley
Sideways view of the trolley
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.
Version 1
Version 2
Version 3
Side trolley view
January - 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, finally deciding on 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.
