Sawbot
Sawbots are close to spinners because they do have a spinning weapon.
But contrarly to spinners or drums that features bars/discs/tribars, a sawbot's weapon is just (as the name implies) a saw or circular weapon (single component) attached to a motor. Middleweight and heavyweights can have multiple saws.
Sawbots suck in Stock RA2, but they can be very efficient in DSL.
Ninja, BOT-204 (and their DSL counterparts) and Spinner from the West are sawbots, but Ripblade isn't one because it has teeth on a disc, and this in both DSL and Stock.
Sawbots do generally less damage by hit than classical bar/disc spinners and have generally more fragile weapons, but they do continuous damage, have lighter weapons and their weapons can't be blocked. Also, if it loses one of it's saws, a sawbot won't wobble like a normal spinner would.
Some argue saws are better mounted as a vertical weapon.