The Evolution and Testing of Aerial Lift Anti-Entrapment Safety Devices

Abstract

First introduced in the 1950’s [2], aerial lifts, also known as cherry pickers, aerial work platforms, and boom lifts, have enabled workers to perform tasks at elevated heights much easier. In many applications with overhead obstructions however, these lifts also present a severe risk to the users, often including fatality. The user can become entrapped due to unintentional involvement with overhead obstacles and be crushed between the lift and the obstacle. In this paper, we present the evolution of the common safety features and anti-entrapment devices that have been developed in response to the growing awareness of the prevalence of these injuries. After these devices are discussed, results are shown for experimental testing of potential crush mechanisms and representative forces. To test the crush force, load cells are attached to a stationary plate in front of a test dummy and forces are recorded to evaluate potential entrapment scenarios. Representative safety device designs are tested, which include mechanical, electrical, and audible features to stop and/or reverse the direction of movement to mitigate or prevent injury. All tests show that having an anti-entrapment device installed drastically reduces the risk to the user and likely prevents fatalities.