Transformers: Generation 1
Gears is anti-social, a self-proclaimed misfit. His tech spec indicated he acted this way to cheer others up as they attempted to cheer him up. However, his portrayal in the animated series indicated he tended to annoy his comrades with his constant complaining. Despite this he never shirks from battle with the Decepticons.
Animated series
Gears was among the original Autobot crew of the Ark which crashed on Earth. In "More Than Meets the Eye" his infrared sensors, a feature of his tech spec, allowed him to track down Ravage, although he left the actual capturing of the Decepticon to others.
Gears' most prominent appearance came in the episode "Changing Gears". Megatron stole a chip from Gears to complete his Solar Needle, a weapon that could pierce the sun itself. The removal of the chip altered Gears' personality from cranky to jovial, and he willingly assisted Megatron in completing the device. However, this eventually backfired on the Decepticon leader as he held Optimus Prime at gunpoint. Prime asked Gears to do him a favour - and he did, sabotaging the device. After the Decepticons were defeated, Gears was restored to his previous personality, and reverted to moaning as the other Autobots drove off without him.
Gears didn't make anymore prominent appearances. A debate can be made that Gears was one of the two Autobots who was dropped into the pool of acid before Jazz, Bumblebee, Cliffjumper, and Spike were saved by Spike's son, Daniel. Although amongst most fans, Gears' only appearance in the film was on Moon Base 1 sitting next to Ironhide before he leaves.