Each clamp is its own independent system, essentially a very powerful permanent magnets sandwiched in the middle of two screw driven scissor lift assemblies. Each screw is driven by a high speed electric motor, which also has an attached battery that always maintains enough charge to lower the jack to the floor.
Operation is simple: plug power into the jack motors and raise them to their full extent; this will pull the magnet away from whatever surface it was attached to. Move the clamp to the desired container and wind down one of the jacks, bringing the magnet into close proximity (or if the clamps are made right direct contact) with a magnet. Move the container to its desired location and lower the second jack, bringing the magnet into contact with the deck.
To release cargo just extend the first set of jacks again. There will still be a little magnetic pull, but due to the distance from the magnet the cargo should now be free.
In case of external power loss each clamp defaults to both jacks retracted, and the slight magnetic pull of the clamps will ensure the cargo attaches securely to the floor unless the ship is under thrust, in which case why the hell is the cargo not secure already?
Pros: easy to use and repair/replace, works on any ferrous item or surface, can be used to clamp containers together, can be manually operated if required, keeps enough distance between container and floor that crush injuries can be avoided.
Cons: 'snaps' to deck comparatively slowly, takes up space in cargo hold with an air gap, reduces surface area on the deck (and thus frictional forces), won't return to the locked position in case of catastrophic electrical event (i.e. Component failure or EMP)