Could you build a leverage tool small and practical enough to save the climber's arm?

Inspired the Aaron Ralston, the climber who amputated his arm to escape from a rock climbing accident.

So I’m thinking, is there something Ralston could have carried to get himself out of a jam like this? Can you build some kind of jack small and light enough to be carried as a routine piece of climbing equipment"

What I envision is a cylinder with two spike pistons coming out of opposite ends. A jacking mechanism in the center, designed so a typical climbing hammer could be put into a rocking sleeve to serve as a lever. (That is, if there IS such a thing as a “standard” climbing hammer – I know nothing about climing.)

Here’s where my vision starts getting real fuzzy – the actual pumping mechanism, since I know next to nothing about hydraulics, either – just a kind of vague feeling about the physics involved.

My choices seem to be fluid-based or air-based hydraulic system, or possibly some mechanical gearing.

As I write this, now I think of it as a screw and nut type design, or actually two screws embedded into a common nut. The threads are at a shallow angle, but thick for strength. The screws are threaded oppositely so they both retract from the common nut when it is turned. Kind of like a negative turnbuckle.

Now upon reading this it seems such a thing must actually exist, though maybe not designed as a climber’s safety tool.

So what would be best? I wouldn’t think you’d want the the cylinder to be any larger than, say, a road flare, or nobody would carry it. On the other hand, that may be too large, 'cause maybe you only have an inch or so clearance to fit the thing in. If they can be small and light enough, maybe you could put several of increasing sizes in a little kit. That way you coud start with a 1/2" that will crank out to an 1", a 1" one that will crank out to 2", etc.

Another related thought is you wouldn’t need much mechanical advantage for it to work. Ralston had five days to prepare to get loose, so you could figure on a similar amount of time available for thousands of pumps on the mechanism.

Maybe there’s some mechanical engineers out there who can give some input to this?