Aerial Work Platforms (AWP’s) 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.
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 can be controlled to extend the lift in a number of different directions, which can often include “up and over” applications.
The majority of manufacturers and operators have strict safety criteria for the operation of Aerial Work Platforms. In some countries, a licence and/or insurance is required to operate some types of Aerial Work Platforms. Most protocols advocate training every operator, whether mandated or not. Most operators also prescribe a range of pre-usage checks of the unit, and manufacturers recommend regular maintenance schedules.
Work platforms are fitted with safety or guard rails around the platform itself to contain operators and passengers. This is supplemented in most models by a restraining point, designed to secure a harness or fall arrester. Some work platforms also have a lip around the floor of the platform itself to avoid tools or supplies being accidentally kicked off the platform. Some protocols require all equipment to be attached to the structure by individual lanyards.
Extreme caution must be taken when using AWPs in the vicinity of overhead power lines, as electrocution may result if the lift comes in contact with energized wiring. Non-conductive materials, such as fiberglass, may be used to reduce this hazard.
AWPs often come equipped with a variety of tilt sensors. The most commonly activated sensor (especially with two people on a lift), will cause the machine to refuse to raise the platform beyond a certain height. Sensors within the machine detect that weight on the platform is off balance to such a point as to risk a possible tip-over if the platform is raised further. Another sensor will refuse to extend the platform if the machine is on a significant incline. Some models of Aerial Work Platforms additionally feature counterweights, which extend in order to offset the danger of tipping the machine inherent in extending items like booms or bridges. Some lifts are also fitted with sensors which will prevent operation if the weight on the platform exceeds the safe working load.
As with most dangerous mechanical devices, all AWPs are fitted with an emergency stop button or buttons for use in the event of a malfunction or danger. Best practice dictates fitting of emergency stop buttons on the platform and at the base as a minimum. Other safety features include automatic self-checking of the AWP’s working parts, including a voltmeter that detects if the lift has insufficient power to complete its tasks and preventing operation if supply voltage is insufficient. Some AWPs provide manual lowering levers at the base of the machine, allowing operators to lower the platform to the ground in the event of a power or control failure or deliberate use of the machine, e.g., by unauthorized persons.
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