Gyro-inhibitor shells are one of many, many weapons invented by Wheeljack. Fired from his shoulder cannon, they're designed to implant themselves in an enemy and wreak havoc on their sense of balance.

Fiction

Generation 1 cartoon continuity

The Transformers cartoon

During a battle between the Dinobots and the Decepticons, Wheeljack pitched in by nailing Megatron with a gyro-inhibitor shell. His equilibrium destabilized, Megatron fell to his knees for a minute or two, allowing Starscream to claim his spot as Decepticon leader. S.O.S. Dinobots

Later, when the Decepticons assaulted Autobot Headquarters, Wheeljack used what Gears called just a "gyro-inhibitor", with no shells involved. This ability, which took the form of waves emanating from his head, was used to cause incoming missiles to explode in midair. B.O.T.

2005 IDW continuity

When he and Hot Rod were surrounded by the Machination's Sunstreaker clones, Wheeljack fired a gyro-inhibitor shell into the air, where it exploded and rained lots of tiny shells down on their attackers. Though the clones were imbued with all of Sunstreaker's knowledge, Sunstreaker wasn't really one for paying attention to Wheeljack's inventions, and as such they were completely unprepared for the shell's effects. While they were busy falling over and driving in circles, the two Autobots made their escape. Devastation issue 3