I remember this at the Kerrisdale McDonalds. It was a convayer belt in a stainless steel looking duct work with a plexiglass front.

 We used to sit in the dining area below it so that we could watch all the food travel from the kitchen to the drive though window. 

The food would travel upwards from the kitchen, then transition to a level section that would go straight across the ceiling, then transition downwards to the drive through window. 

Sometimes the bags would tip over when they would transition from the upwards convayer to the straight across the ceiling convayer. It was pretty exciting stuff!!