Lego models are usually too fragile to cope with outdoor play. Especially off-road outdoor play.
This one isn’t.
(Via, once again, the excellent TechnicBricks.)
And yes, those are pneumatic remote-control tubes going to this particular vehicle. Here are lots more pictures from the “Czech Lego Technic Truck Trial Championship 2008″, organised by members of this Czech Lego forum.
Making off-road Lego models is, I think, a good introduction to real full-scale engineering. A Lego truck trying to negotiate one-inch pebbles is taking similar risks to a full-sized vehicle trying to get over boulders. The Lego truck’s much more likely to fail, for much more realistic reasons, than a “normal” off-road toy truck.
This is because of the square-cube law, which makes it easy to make a model that’s far stronger than a full-sized version would be. The connections between pieces of Lego are weaker than the connections between the components of a normal off-road R/C toy, which makes the challenge more realistic.
If you build a small bridge out of Lego, you can just stick together a few layers of beam pieces using nothing but the standard stud connectors, and it’ll work. This sort of thing doesn’t scale at all, though, as many kids facing the classic “Spaghetti Bridge” challenge have discovered. In scale terms, spaghetti behaves like steel.
As, for that matter, do the engineering components available to you in the old Bridge Builder game and its descendants. In those, the girders are stiff and strong, but they’re nowhere near long enough to bridge the gaps all by themselves. And the joints with which you stick girders together are all perfect hinges, and not very strong in tension.
Getting a tracked Lego vehicle to work properly offroad, and not throw a track every time a tiny stick or pebble gets jammed in there, would be a serious challenge. It might also give you some sympathy for the people who have to spend three hours with a sledgehammer, a two-by-four and who knows what else, fixing full-sized tracked vehicles that’ve done the same thing, in some delightful place or other.