The most recent major structure required for my steel mill-based layout was an ore bridge – not just any ore bridge, but one that is capable of unloading Great Lakes ore boats. I’m referring to the kind with a drawbridge-type overhang on the waterfront end that can be raised while the ship is being guided in and out of the dock. As with my other structures, this was definitely NOT a pure replication of a specific prototype but [rather] a “plausible generic” representation.
After building and powering the tram/bucket hoist mechanism in early May 2004, I concluded that the original main and extension spans were too flawed to use in building what I considered to be an acceptable model. So, I proceeded to gather all the required brass structural shapes - some of which had to be special-ordered - and construct entirely an entirely new main span, extension span, and support legs. The tram, hoist and clamshell bucket were the only original items worth saving.
It was an enormous amount work, but well worth the results. It still awaits a permanent home on the new Iron Belt layout which will hopefully be "completed" before the Spring of 2006. The one and only time I've had it painted and fully assembled was at the September 2004 Steel Mill Modelers' Meet in Malvern, Pennsylvania.
I never found the time to prepare any detailed text on the second bridge as I did on the first, but here is a photo essay of the construction milestones that I've managed to kluge together, along with different angle views of the assembled but unpainted structure. 5 weeks after the Malvern convention, Walthers announced their own Cornerstone Series kit of a Traveling Overhead Crane, sparing modelers the toil and trouble of scratchbuilding any ore bridges of their own.
The inspiration for my model is a bridge at the US Steel Zug Island ore dock near Detroit, Michigan.
A sketch (not to scale) of my simplified model appears in ob_draw_overview.gif.
Unlike any of my previous models, this one will be 85% brass – this is the only material I can trust not to bend or sag. The frame, legs, and heavy bracing will be metal; the details like thin bracing, walkways, stairs, and handrails will be styrene.
At this point, I have completed the brass part of the forward and rear legs and assembled the 10 interior cross braces. My project was delayed when I discovered, after closer examination of John Teichmoeller’s photograph above, that the original legs I had built were totally incorrect so I needed to acquire the necessary brass shapes and build new ones (see pictures at links below).
Assembled sides of the two forward legs (below bridge level): ob_model_wide_legs_01.jpg
An assembled leg beside the brass pieces of an unassembled leg: ob_model_wide_legs_02.jpg
Two I-beam sections of a rear leg. The long piece was partially cut at the ridges, then bent.
Diagram of interior cross brace section, assembled and ‘exploded’: ob_draw_inner_brace.gif
Assembled rear and forward legs: ob_model_all_legs_01.jpg
Partially-assembled top and side sections of interior braces: ob_model_inner_brace_01.jpg
Inside cross braces and frame bottom: ob_model_inner_brace_02.jpg
A stack of ten assembled cross-brace sections: ob_model_inner_brace_04.jpg
L-girders to be used for top of frame: ob_model_top_long_beams_01.jpg
…and that is where I’m at with the ore bridge as of October 20, 2003. –KJL