Treadwheel Crane
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Basic Information

A treadwheel crane (also known as a treadmill crane) is a huge man-powered construction device used to lift heavy objects to great heights. Construction cranes are not nearly as new and recent a technology as you might imagine. They go back to Ancient Rome, and were used throughout the Middle Ages to make castles and cathedrals.

But how did they make that work in an age before power winch? How do you generate enough lift with just human power? The answer is: put the humans in a giant hamster wheel.

I'm not kidding. In some versions, it's two wooden hamster wheels side-by-side, sharing a central axle that they use to wind up heavy rope for lift.

And it gets better. The people in the hamster wheel were usually blind. This was because the Treadwheel Crane would be put way up high on scaffolding above the highest point of the cathedral you're trying to build, and people with functional eyes tended to freak out being that high up for probably the first and only time in their life. There's also a bit of danger of the axle potentially popping out and dropping you a hundred feet or more to your death. Being a Treadmill Worker on a tall project is a harrowing, perilous job.

Effectively the treadwheel crane functions like a standard crank, and with the diameter of the wheel being so large it takes hardly any effort or energy to lift a thousand-pound rock slab, pallet of timber, or huge bucket of construction stones.

Such cranes could also reasonably be expected to appear in higher end port facilities, allowing heavy cargo to be unloaded (lighter material could be lifted by simple counterweight cranes or portaged out by stevedores and longshoremen).


1. Video: Worst Jobs of the Middle Ages - shows a functional treadwheel crane that is operated by two people inside it just walking at a normal pace. With just that effort, they are able to lift a modern car, easily… until the axle starts to pop out the side and has to be hammered in by another worker on the outside to keep it from dropping the wheel.

Game and Story Use

  • The medieval construction site is a great set for a fight scene. Multi-leveled scaffolding to jump around on or snipe from. Hundred foot drops that do enough damage to make even an epic-level character think twice (or add Feather Fall to their spell list). Some huge hunk of rock being swung around on a gantry by a couple of blind men, potentially smashing into someone like a wrecking ball every turn or two.
    • Placing a crane in the background of an early scene to foreshadow this would be a good idea.
    • If the BBEG is some sort of nigh-invulnerable immortal, your foreshadowed crane could actual be a well-planted tool for clever players to use against the villain later. He's immune to most damage, but he's probably not immune to being pinned under a few thousand pounds of boulders for eternity. Or you could just use a swinging load as a huge flail (for example, see the Scooby Gang's battle against Glory in Buffy the Vampire Slayer.
  • The PCs are working a murder mystery or similar investigative scenario in the middle ages or ancient world, and are told there's a witness to the crime. They'll have to go to talk to him at his new job site, because the witness has been drafted via a corvee system to help build a new cathedral. They get there, and are told he's 120 feet up, in that rickety spinning wheel. We can't delay the construction of the new house of god, says the Bishop, so the only way you can question the witness today is if one of the PCs climbs up there and joins him the crane. Insert some sort of climbing or athletics check for dramatic tension. Optionally insert some sort of joke about blind justice when you get to the top of his testimony, if it's that sort of a game.
  • An accident involving a crane could be a good way to insert some disaster/tragedy into the background of your setting.
  • Seems like a good match for dwarf or gnome tech, if you don't want to go full-on steampunk.
  • The treadwheel can be used for all sorts of power demands besides cranes, including driving industrial plant and mills - the same operators could be moved between wheels driving the cranes and those working a sawmill cutting beams (or stone), pumping water or milling rubble for hardcore or cement, or blowing the bellows for a lime furnace. See also mines and quarries.
    • It actually long outlived its practical usefulness as a piece of prison furniture where it was used to both exercise and punish convicts - sometimes attached to nothing more than a braking mechanism to apply load.
  • Give the PCs a multi-ton McGuffin to haul about and they are likely to develop an appreciation for these things. Make them take it to the middle of nowhere and they will need to learn how to build one - which may be the sort of Guild mystery that is not sold cheaply.
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