Gravity feed is the use of

earth's gravity The gravity of Earth, denoted by , is the net acceleration that is imparted to objects due to the combined effect of gravitation (from mass distribution within Earth) and the centrifugal force (from the Earth's rotation). It is a vector quanti ...

to move something (usually a liquid) from one place to another. It is a simple means of moving a liquid without the use of a pump. A common application is the supply of fuel to an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...

by placing the fuel tank above the engine, e.g. in

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

lawn mower A lawn mower (also known as a mower, grass cutter or lawnmower) is a device utilizing one or more revolving blades (or a reel) to cut a grass surface to an even height. The height of the cut grass may be fixed by the design of the mower, but g ...

s, etc. A non-liquid application is the carton flow shelving system. Ancient Roman aqueducts were gravity-fed, as water supply systems to remote villages in developing countries often are. In this case the flow of water to the village is provided by the hydraulic head, the vertical distance from the intake at the source to the outflow in the village, on which gravity acts; while it is opposed by the friction in the pipe which is determined primarily by the length and diameter of the pipe as well as by its age and the material of which it is made.

See also