The Franklin Crane’s Final Lift: A Heavy Goodbye

In April, we moved our Franklin Crane out of the museum. It had been stored on the museum’s second floor for many years, but now it was time to say goodbye. First, we rolled it across the second floor storage area. Then came the hard part: getting it downstairs. This crane is nearly 9 feet tall and weighs maybe half a ton—maybe more! To make it easier to move, we took the crane apart. There are eight big bolts joining the top and bottom parts. Each bolt has a hex head that’s one inch wide across the flats.

There are also two threaded fasteners keeping things together at the base of the crane. These fasteners have 7/8-inch diameter threads, and the nuts are 1 1/2 inches across the flats.

We’re thankful to the previous owners who kept the crane dry for 100 years or so before it even got to APM.  Where there’s rust on the crane, it’s mostly superficial.  The bolts and fasteners came apart pretty easily—another clue that the crane had likely been taken apart when it was first brought to the museum. That would also explain how it ever made it up to the second floor in the first place!

When I talked with our founder, Ed Battison, about the crane years ago, I asked, “Why don’t we use this?” He explained that it had a very basic and unsafe steering system; it was subject to tipping over to the side. It’s the same steering system that you find on a little red wagon. As you turn the handle left or right, the footprint of the rear wheels gets smaller and smaller, making it easy to tip over. On this crane, the rear wheels were already narrower than the front ones to begin with, so turning made it even less stable.

And there’s another serious design flaw: the braking system only works when the wheels are pointed straight forward and the handle is in the vertical, upright position. When the handle is up like that, a sort of cast iron “knife-edge” rests against both back wheels to stop them from turning. Yes, what I’m saying is there’s no brake at all while you’re steering. And if the handle isn’t vertical, the brake doesn’t work either. You can’t move the crane with the handle straight up, and you can’t stop it with the handle down.

Back to those two threaded fasteners I mentioned earlier—they’re welded to thick wrought iron strap that runs from the base to the top of the crane’s arched “neck.” There are two more of these threaded devices, welded to the other end of the straps at the top. These straps are important. Most of the crane is made of cast iron, which is somewhat subject to cracking. Wrought iron (which is much less prone to cracking than cast iron) straps effectively spread the weight of the load across the arched frame and reduce the chance of cracks. They also hold the crane together in case of catastrophic failure.The strap’s threaded fasteners at the top of the crane, pass through a tube built into the casting. Then they pass through a semi-circular iron plate at the end of the crane that is formed by a different means: forging.

If you look closely, you can see a couple of strange bumps near the joint between the tube and the curved plate. These “lips” are casting flaws—places where the molten iron didn’t fill the mold properly. Right next to those lips is a crack in the metal, probably caused by that flaw. The crack ends in a pillow block (a kind of support that holds an axle), which broke completely and even lost a chunk at some point.