An aerial work platform (AWP), also known as an aerial device, elevating work platform (EWP), cherry picker, bucket truck or mobile elevating work platform (MEWP) is a mechanical device used to provide temporary access for people or equipment to inaccessible areas, usually at height. There are distinct types of mechanized access platforms and the individual types may also be known as a "cherry picker", "boom lift" or "scissor lift". They are generally used for temporary, flexible access purposes such as maintenance and construction work or by firefighters for emergency access, which distinguishes them from permanent access equipment such as elevators. They are designed to lift limited weights — usually less than a ton, although some have a higher safe working load (SWL) — distinguishing them from most types of cranes. They are usually capable of being set up and operated by a single person. Regardless of the task they are used for, aerial work platforms may provide additional features beyond transport and access, including being equipped with electrical outlets or compressed air connectors for power tools. They may also be equipped with specialist equipment, such as carrying frames for window glass. Underbridge units are also available to lift operators down to a work area. As the name suggests, cherry pickers were initially developed to facilitate the picking of cherries. Jay Eitel invented the device in 1944 after a frustrating day spent picking cherries using a ladder. He went on to launch the Telsta Corporation, Sunnyvale, CA in 1953 to manufacture the device. Another early cherry picker manufacturer was Stemm Brothers, Leavenworth, WA. Other uses for cherry pickers quickly evolved. Lifting mechanisms There are several distinct types of aerial work platforms, which all have specific features which make them more or less desirable for different applications. The key difference is in the drive mechanism which propels the working platform to the desired location. Most are powered by either hydraulics or possibly pneumatics. The different techniques also reflect in the pricing and availability of each type. Aerial device Aerial devices were once exclusively operated by hydraulic pistons, powered by diesel or gasoline motors on the base unit. Lightweight electrically powered units are gaining popularity for window-cleaning or other maintenance operations, especially indoors and in isolated courtyards, where heavier hydraulic equipment cannot be used. Aerial devices are the closest in appearance to a crane – consisting of a number of jointed sections, which