Transformation cog (biology)
| The name or term "Cog" refers to more than one character or idea. For a list of other meanings, see Cog (disambiguation). |

A transformation cog, also referred to as a transforming cog, transition cog, conversion cog, or T-cog is a component important to a Transformer's transformation and sometimes scanning.
Fiction
The Transformers cartoon
Metroplex's cog was damaged in 2005 during the Decepticon siege of Autobot City, which explains why he did not transform to robot mode during the battle. Perceptor built a replacement cog and entrusted its delivery from Cybertron to Autobot City on Earth to Blurr and Wheelie. This proves you can be brilliant but still stupid. Five Faces of Darkness, Part 1
After numerous setbacks, the cog was delivered just in time. As the city was under siege once again, Pipes quickly installed it, allowing Metroplex to fight off Trypticon. Five Faces of Darkness, Part 5
The cog also makes a nice substitute for a football. Apparently, it can also change its shape to look like flat, toothed wheel every time a lazy animator wishes it.
Unicron required Trypticon's cog as part of his scheme to use Cybertron as his new body. Ghost in the Machine
Swindle stole Metroplex's cog, causing the Autobots to retaliate by stealing Trypticon's. Both factions hit upon the idea of using the captured cogs on their respective city warriors, an idea that was only partially successful. The Ultimate Weapon
Dawn of Future's Past
While speeding to defend the Golden Disk from Predacon thieves, Nitrostreak was shot in the hood by one of the criminals, damaging his transformation cog. As he was also flipped on his roof by the blast, he was well and truly incapacitated for the moment. Dawn of Future's Past
IDW Generation 1 comics
Together with the spark and the brain module, the transformation cog was part of the "Rossum's Trinity" principle of Cybertronian biology. Enough damage to one of the three would cause the other two to shut down, killing the Transformer in question. The Chaos of Warm Things
Tailgate broke his legs, internal clock and transformation cog from falling through the Mitteous Plateau. How to Say Goodbye and Mean It
To "reject" Adaptus, the Militant Monoform Movement surgically removed their transformation cogs. Life After the Big Bang
Pharma was forced to make a deal with the Decepticon Justice Division to harvest Delphi's patients of their transformation cogs in return for the facility's safety. How Ratchet Got His Hands Back
Megatron's transformation cog was shattered during the Battle for Hell's Point, leaving him stuck in gun mode for a whole two years. Chaos Theory Part 1
When Orion Pax found his colleague Springarm dead, his transformation cog was "still warm", allowing Orion to transform the dead body into its alternate mode. Chaos Theory Part 2
When his unit was ambushed by Decepticons, Tracks was injured and couldn't transform due to a damaged transition cog. Spotlight: Jazz
Shockwave created an experimental weapon to override a Transformer's primary transformation cog and lock them in their alternate mode. Iguanus used it on Soundwave during a battle, forcing him to remain in his cassette deck mode for 25 years. Spotlight: Soundwave
In protest of the Autobot "occupation" of a peaceful Cybertron, a NAIL transformed repeatedly for weeks until his transformation cog wore out and he died. How to Say Goodbye and Mean It
War for Cybertron
In order to prevent Iacon's destruction at the hands of the battle station Trypticon, Air Raid proposed that his team blast Trypticon's conversion cog, forcing him back into robot mode and hopefully ending the chaos. The cog was blasted to bits and Trypticon was unable to maintain his station mode. Unfortunately, this had the slightly troublesome effect of dumping a heavily-armed, very angry giant Decepticon onto Cybertron instead. Transformers: War for Cybertron In addition, when a player's health is completely depleted in a co-operative or online mode of gameplay, the Transformer being controlled will fall to the ground and begin a countdown to going offline. While the countdown is in process, it can be seen that a notice on the side of the screen reads "TRANS-COG: OFFLINE" and the game does not allow the player to transform during the countdown. This implies that heavy damage to a Transformer can disable their conversion cog.
Prime cartoon
T-cogs are bio-mechanisms that enable Transformers to scan alternate modes, transform, and operate integrated weapon systems. Transformer organs such as these are beyond Ratchet's ability to construct.
Requiring a part for the robot they were building, MECH ambushed Bumblebee and stole his T-cog. Unfortunately when they attempted to install it into their robot, it failed to work, as it required energon to function properly. Operation Bumblebee, Part 1
It worked better once they got some energon, but it was badly damaged when Bumblebee attempted to take it back. Despite the damage, Ratchet was able to repair it enough that Bumblebee regained the ability to transform. To make up for their loss, MECH stole Starscream's T-cog instead. Operation Bumblebee, Part 2
Now armed with greater knowledge about Cybertronian biology and Starscream's T-cog, MECH was able to create Nemesis Prime before Optimus defeated it and the US military confiscated it. Nemesis Prime
Starscream later tried to install a T-cog he took from his Clone aboard the Harbinger but was interrupted. Triangulation
Notes
- In the Generation 1-related fiction, damage to a transformation cog traps the Transformer in whatever mode he or she happens to be in (most often this is their alternate mode). In War For Cybertron, the destruction of his conversion cog instead forces Trypticon into robot mode.
- In the IDW universe, a transformation cog can still be functional for a short time even when a Transformer is deceased, as demonstrated when Optimus used the corpse of a fellow Autobot as a vehicle.
Foreign names
- Japanese: Transform cog (トランスフォーム・コグ toransufōmu kogu)

