Next character in line coming from Transformers: Dark of the Moon is possibly the one who’s been changed more, aesthetically. As Sentinel Prime is reactivated, Megatron (apparently) sends his assassins after him, the Dread: Crowbar, Hatchet… and Crankcase, who’s the only one coming from the source material. Crankcase puts up quite a show by defeating Sideswipe, only to be killed by Ironhide immediately after. The original Crankcase doesn’t look anything like this beastly robot with dreadlocks who vaguely looks like an unmasked Predator, and he’s a much more classic Decepticon: let’s take a look.
Crankcase was born on Cybertron, millions of years ago, and albeit it’s quite relative to say, he used to be very small for a Cybertronian. Before the beginning of the Great War, he worked as a menial janitor in the Fuel-Spill Section of the Ministry of Energy and Nutrition, a government job that he simply loathed… mainly because everyone bullied him on a constant basis, exploiting his weakness and his status. When the war began, Crankcase was among the quickest to fall in line behind Megatron 
and become a Decepticon… but he had a price: a more powerful body. Megatron saw some potential in all that grudge, and he granted the little one’s request: Crankcase received a new body, with a lot of firepower, and the first thing he did with this new power was to raze down his place of work, with all his ex-coworkers inside. From that moment, Crankcase always followed Megatron, not because of loyalty or gratitude, but because with the Decepticons he had a greater chance to cause some serious damage to the people he hated… which is to say pretty much everyone (Megatron included, most of the times). Crankcase was now one of the Triggercons, a trio of small-sized Decepticons who however packed quite a punch with the many, many weapons equipped to their bodies: along with his mates Windsweeper and Ruckus, he had some fun as Megatron’s support troops, even if they botched a mission spectacularly when they let Optimus Prime, leader of the Autobots, steal the Underbase (the collective knowledge and experiences of all the Cybertronians who ever lived) right from under their noses. Then, Megatron disappeared along with his ship and a bunch of other Decepticons, and things on Cybertron changed very fast, and for the worse… at least for Crankcase.
The Decepticons underwent many changes in leadership in over four million years, and Crankcase somehow found himself back to his original position: a little slave-like laborer under some big guy at the top. To give the Decepticons more stability, a Triumvirate was formed, with the three warlords Legonis, Octus and Seizer in power. The trio, however, soon got lazy with all their power, and their rule was one of decadence and luxury… for them, at least. Crankcase and the other Triggercons were 
considered “cute little mascots”, and kept at the palace as house servants. Things continued this way for a lot, until someone unexpected came back: Megatron himself… well, actually a fusion of Megatron and Straxus, a deceased (?) Decepticon tyrant. The Triumvirate understood the menace Megatron represented to their power, and they threw him in their gladiatorial arena to have him killed, but the Decepticon leader put up an inspirational speech, remembering the Decepticons’ true values, their valor in combat, their hatred for the Autobots, creating quite a general nostalgia for the good times of war. Also the Triggercons were influenced by Megatron’s speech, and they turned against the Triumvirate: they shot them in the back, vaporizing all three of them, and then proceeded to free Megatron, ready to come back on the battlefield under his insignia. At first, Megatron used the Triggercons as recruiters, looking among the now peaceful and decadent Decepticons some warrior worthy and willing to join the cause. Crankcase wasn’t very happy with the task, as he was already tasting battles, but he did as he was told. He also traveled to Earth to retrieve a new Decepticon leader when the inner conflict between Megatron and Straxus brought to a weird self-destruction, and the one he found was Thunderwing: the perfect candidate, but a cookie a bit too tough even for the warmongering Decepticons…
Crankcase is, simply put, angry: he holds a grudge against everything and everyone, and he’s all too eager to “make them pay”, whoever “them” may be. As a Triggercon, despite being much smaller and weaker than regular Cybertronians, he’s equipped with heavy weaponry, the most visible and lethal of it being the two double-barreled laser cannons mounted on his shoulders; during his time on Earth he also gained the ability to turn into an off-road camper-like vehicle, gaining some extra speed. Bullied and underestimated all his life, Crankcase now only feels hatred and rage, and he’s ready to vent it over anyone: he complains all the time about any kind of things, and nobody is every on his good side… no wonder even the other Triggercons eventually abandoned him, everything considered.
Who's Who 