Not much of a view, but a hell of a ride
April 19, 2010 9:39 PM   Subscribe

What sort of contraption did I see today slung underneath a semi trailer?

Today, while driving to work today in the Greater Seattle Area, I saw a semi with a minivan trailing behind it with a lit "oversize load" sign. The load for the semi appeared to be the normal width of a trailer, but somewhat longer. The semi was white with a few Boeing logos on it, so I assume the load was part of a plane.

This did not surprise me. However, while passing the semi, I noticed that the rear end of the trailer, in front of the rear axles, had what I can only describe as a "pod" slung underneath it. The pod had windows in it and had side view mirrors at least on the side I could see. I'm pretty sure the pod was facing the direction of traffic, but I might have been mistaken. Inside the pod was a guy with what appeared to be either a radio or a cell phone. He also appeared to be suspended only a few feet above the ground, albeit in a self-enclosed unit attached to the bottom of the trailer.

What is the purpose of this pod and rider?
posted by saeculorum to Grab Bag (4 answers total) 3 users marked this as a favorite
this pod allows the rear driver to steer the rear wheels on the trailer, which makes it infinitely easier to get an oversize trailer around awkward corners and other tight spaces.
posted by phredgreen at 9:45 PM on April 19, 2010 [1 favorite]

It was a steerable trailer, used by Boeing for transporting over length loads like wing spar beams. The guy in the "pod" can steer the rear wheels of the trailer around corners, cutting the effective turning radius of the rig.
posted by paulsc at 9:48 PM on April 19, 2010 [5 favorites]

There was a 5-part PBS documentary about the building of the 777 that I posted to the blue back in December. At about the 41:30 mark of part 2, they spend a couple of minutes showing one of these trucks, including some footage shot from inside the rear cab.
posted by FishBike at 6:21 AM on April 20, 2010

Very long ladder fire trucks have this feature, too, as immortalized (for me, anyway) in this 1978 video game, Fire Truck [2].
posted by dammitjim at 6:26 AM on April 20, 2010

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