I enjoyed playing with my LEGO Technic Crane Truck, but it definitely had room for improvement. One particular disappointment was in the limited motorized articulation of its namesake crane. When I saw another crane truck set LEGO Technic Unimog U400 (8110) I was intrigued by the pneumatic piston articulation of its crane. It is easier to run air hoses instead of axles to transmit power through a crane mechanism, would it prove to be a superior solution? I parted with some of my money for an answer.

I don't know if LEGO Technic Crane Truck was modeled after any specific truck, but this set has Unimog U400 in the name. Looking at this Unimog U400 picture on Wikipedia, I say it's a pretty good likeness. Even better, the resemblance is more than skin deep.

A signature feature of the Unimog line is the portal axle system giving them greater ground clearance. I'm happy to report LEGO reproduced the portal axles via these wheel hub gears.

To take advantage of the ground clearance, this set also had coil spring suspensions front and rear so the truck can traverse uneven ground. It's a solid axle design, located by what I now know as a Panhard rod thanks to this Autopian article.

There is again only a single electric motor in this set, with a gearbox that let us either use its rotational power directly or to drive the pneumatic air pump.

The mechanical or pneumatic power is then directed to either front or rear accessory mounting points.

A four-cylinder engine drives all four wheels, and the engine is visible under the cab once it is tilted forward as the real truck does.

The drivetrain and steering mechanisms are not motorized in this set, but I noticed their related geartrain components used shafts that were longer than necessary. The extra length poked into an empty space behind the gearbox, under the cargo bed. I think these are provisions to help anyone who wants to turn this into a remote-control vehicle.

The sizable cargo bed can accommodate a LEGO WALL-E. (Sold separately.)

After the truck was built, we build the removable accessories front and rear. The default front accessory is a winch that runs off the mechanical accessory drive, a fairly straightforward affair. The star of the attraction is in the back: a crane with gripper end that operates on both mechanical and pneumatic accessory drive. The mechanical driveshaft turns the rotating base to control azimuth. Three levers control pneumatic pressure delivered to a corresponding piston: shoulder joint elevation, elbow joint elevation, gripper open/close, or some combination thereof.

I was intrigued by the theoretical capability to operate the crane purely on power controls, unlike Crane Truck where we had to manually reach out to the crane arm to turn knobs for crane extention and winch. And technically speaking, this set delivered on the promise of full power control. Practically speaking, though, the pneumatic system didn't work very well. The biggest problem is gravity. Raising elevation on each joint is a slow process as the air pressure fought against the weight of the system. When the lever is flipped in the other direction, that weight crashes down and the joint immediately collapses. With each pneumatic control lever a binary on/off affair, I found it impossible to keep descent rate under control.

Even if the pneumatically operated crane arm turned out to be a disappointment, the rest of the truck was still fun to play with. In the future, I might even take up the invitation to turn it into a remote-control vehicle! As for crane arm articulation, my next LEGO Technic purchase would return to the world of mechanical linear actuators.