Tractor beam
A tractor beam or stabilizing beam was an attenuated linear graviton beam used by starships and space stations to control the movement of external objects. The tractor beam placed spatial stresses on the object in specific areas, allowing it to hold the "tractored" object in a fixed location or alter its position and/or trajectory. While tractor beams were normally used to pull objects towards the beam source – usually to tow objects – conversely, they could also be set to repel objects. They were most often employed to tow a disabled or vulnerable ship to safety, or sometimes, used by an enemy ship to control the movement of the target vessel. (; ; ; ; )

Tractor beams were generally only used at sub-warp velocities. To safely tow a vessel at warp speed, the target vessel's engines had to be deactivated to avoid shearing forces against towing vessel. A tractor beam could be used at warp speed only if both vessels' speeds were exactly matched. (; )

Before the development of the tractor beam, Earth starships such as  instead used the more primitive grapplers. Other species like Vulcans, Klingons, and Malurians already used tractor beams by the mid-22nd century. (; )

The First Federation vessel Fesarius was capable of towing a  vessel at high warp for prolonged periods without stressing the hull of the target ship. () Borg vessels also had the capability of holding starships securely while traveling at warp speed. ()

In 2293, a tractor beam was one of several pieces of equipment and personnel lacked by the  during its maiden voyage, as it was not slated to be installed until the Tuesday after. ()

Wesley Crusher created a model of the type of tractor beam that the  used as a science project, before Geordi La Forge inadvertently infected him with the Psi virus brought over from the . While under the infection's influence, he seized control of engineering and was able to reconfigure the ship's tractor beam into a repulsor beam, allowing the Enterprise to push itself away from the Tsiolkovsky and avoid a stellar core fragment from a nearby collapsing red giant. ()

If a vessel's tractor beam is strong enough, its graviton field can reinforce the structural integrity of a target vessel, keeping its hull from succumbing to stresses normally exhibited by a tractor field. ()

When using a tractor beam to force another vessel out of warp speed, otherwise known as a "warp tow", both vessels needed to match velocity at the time of the tractor beam initiation. This brought tremendous risk to both vessels. However, if both vessels' hulls were strong enough to withstand the stress, they could both be brought out of warp with the tractor beam still engaged if the towing vessel carefully disengaged the warp drive while engaging the impulse engines. ()

Most Federation vessels were equipped with a tractor beam emitter on the aft ventral hull, as it was the best location for towing objects. Secondary emitters were also placed in other locations. Smaller emitters were installed within shuttlebays to assist in docking and landing maneuvers. ()

A low frequency tractor beam projected against a planet's tectonic plates was capable of producing minor earthquakes. ()

The stress of a Romulan tractor beam caused sub-microscopic deformations in the structural integrity, specially the nose section and aft thrusters, of the Type 15 shuttlepod Onizuka, when used in an effort to stop a target craft. ()

The Borg favored the use of a considerably more advanced tractor beam when engaging in combat. The Borg beam was capable of rapidly draining a vessel's shields while holding the vessel in place, rendering it virtually helpless against the cutting beam that it was often used in conjunction with. Furthermore, the sheer size of the Borg cube permitted the tractor beam to be used with considerable effectiveness against even ships as large as the USS Enterprise-D. They also had the ability to utilize tractor beams at warp velocities. (; ; )

In 2369, the Klaestrons disabled the tractor beam aboard Deep Space 9 when they kidnapped Lieutenant Jadzia Dax by creating a residual charge in the graviton generator. ()

The same year, Deep Space 9's tractor beam was holding the Federation freighter Norkova after it was hijacked by Rao Vantika, Durg, and two Bajoran mercenaries. Later, Lieutenant Dax sent an electromagnetic pulse via the tractor beam to free Doctor Julian Bashir from the consciousness of Vantika. ()

A carefully modulated tractor beam could be used to affect ship-to-ship weaponry. In 2372, Lieutenant Commander Worf of the  suggested using such a beam against a  attack cruiser. When put into practice, his plan was successful, deflecting some of the vessel's disruptor fire and reducing its effectiveness by fifty percent. ()

In 2371, B'Elanna Torres devised a plan to create a subspace tractor beam, which was a standard tractor beam modified to match subspace interference. This modification required more power than a standard tractor beam and could cut through subspace interference. This tractor beam was also able to project long distances. ()

See also
Tractor rig
Mooring beam
Multiphase tractor beam
Grappler
Subspace tractor beam

External links 
 
 

cs:Vlečný paprsek
de:Traktorstrahl
fr:Rayon tracteur
ja:トラクター・ビーム
Transportation technology