Abstract: The invention provides an indirect linkage between a spring and a hatch supported by the spring. The torque or moment applied by the hatch is significantly curved. The indirect linkage which provides a first varying moment arm and a second varying moment arm and utilizes a varying ratio between the first moment arm and the second moment arm to provide an applied spring torque which matches the shape of the torque curve applied by the hatch.

Abstract: The invention provides a plurality of tray cart containers, in which at least four tray carts are loaded into a tray cart container, and a trailer, wherein the trailers have at least one powered conveyor system, and wherein at least four of tray cart containers are loaded onto the powered conveyor system. A tractor unit is attached to the trailer and transports the trailer from a kitchen to an airport. A container loader removes the tray cart containers from the trailer and transports them to an airplane. The tray carts are removed from the tray cart containers and placed in the airplane kitchen. Other tray carts are removed from the airplane and placed in the tray cart containers. The container loader loads the tray cart containers into the trailer. The trailer is transported from the airport to the kitchen.