^The Stargate only needs to spin when being manually dialled.
For the uninitiated, a Stargate has a secondary, backup dialling system for use in the event of the DHD being unavailable. Running sufficient amounts of electrical power through a Stargate causes the inner ring to unlock, allowing that ring to be rotated manually.
The SGC gate spins because they use this backup system as a primary system, they appear to have motors attached to the Stargate that cause it to spin, dialling the appropriate address.
Think of it like a phone that, for some reason, had a touch tone keypad and also an old rotary dial in case the touch tone pad didn't work.
The Stargates in Atlantis appear not to have an inner ring. I cannot remember them ever manually dialling a Stargate, but I may be wrong.
For the uninitiated, a Stargate has a secondary, backup dialling system for use in the event of the DHD being unavailable. Running sufficient amounts of electrical power through a Stargate causes the inner ring to unlock, allowing that ring to be rotated manually.
The SGC gate spins because they use this backup system as a primary system, they appear to have motors attached to the Stargate that cause it to spin, dialling the appropriate address.
Think of it like a phone that, for some reason, had a touch tone keypad and also an old rotary dial in case the touch tone pad didn't work.
The Stargates in Atlantis appear not to have an inner ring. I cannot remember them ever manually dialling a Stargate, but I may be wrong.