Vertical maneuvering equipment

The Three Dimensional Maneuver Gear (立体機動装置), also called Vertical Maneuvering Equipment, is a set of gear developed by humans that allows great mobility when facing the Titans in combat. The gear allows the user to fight in a 3D space as opposed to a 2D one. The gear itself takes the form of a body harness that encompasses much of the body below the neck. Although the Gear can grant a skilled user tremendous mobility, it is a demanding art that requires strength, and skill, both of which must be honed through constant practice. Some tools involved in the apparatus include:


 * Handgrips
 * Piston-shot grapple-hooks
 * Gas powered mechanism
 * Iron Wire Propeller with Plug in Blades

Usage
The simplest move possible with the 3DMG is simply aiming and firing the grapple hooks at an object and then activating the gas mechanism to reel oneself toward said object. They can then disconnect the hook and continue moving forward.

Usually however, soldiers must be able to move around in order to navigate in general. Therefore, they tend to use their momentum in order to swing around targets.

More advanced techniques include changing directions while still being reeled in as demonstrated by Jean Kirstein.

Levi often uses a very advanced technique. After hooking the wire onto the Titan's neck, he releases the hook, and does 2~3 spins. Finally, he strikes down on the Titan, killing it.

Origin
The circumstances regarding the creation of the 3DMG are detailed in the prequel novel Before The Fall. 3DMG was invented between 775 (year of the Titan attack and BTF's prologue) and 788 (13 years later) by Angel Aaltonen, a first-class weapons craftsman who worked closely with the Survey Corps.

Mechanics
The Body of the Device - Steel wire is stored inside the body. There are two axles, which revolve independently.

Operating Device - The functioning part of the operating device is a black box, which the technical department manages and improves in secrecy.

Body of the Compressed Gas Cylinder - Gas is compressed into the cylinder and injected.

Fan Section - Gas is blown directly into the fan to make it rotate. The pressure of the gas is regulated to manipulate the output.

Training
Three-dimensional maneuver device training is a rigorous process that allows humans, which are limited to two-dimensional movements, to adapt to movement in the third dimension.

Great physical strength, particularly in the legs, coupled with spatial recognition abilites, as well as the mental strength to not waver in the midst of a panic, are crucial qualities.

One of the first things done after enlisting in training is the 3D Maneuver Gear aptitude evaluation. Those unable to remain upright are dismissed.

"Those incapable [of staying upright] aren't suited to even be used as decoys!"

Three years of training is needed before officially becoming a soldier. Many run away or are driven out before graduating. The training is so intense that some people actually die during the process.

Trivia

 * As of Chapter 58, Gunfire, the members of the Central Military Police's Anti-Human Suppression Squad are shown wearing a variant that is quite different from the standard 3D Maneuver Gear used by the regular forces. While the basic principles for maneuvering in it are the same, the design is drastically different with the bulk of the device worn over the shoulders rather than the hips, one tank of compressed air on the back rather than two mounted on the blade sheaths, and with the grapple-hooks being fired from the handgrips rather than from the blade sheaths. In addition, the swords are replaced with high powered pistols that are reloaded with the barrels being discarded and replaced with others stored in bandoliers worn over the thighs of the wielder.