April 24, 2019 by Michael Catapult effect in a boom lift This is why a harness is required in a boom lift. Small movement of the wheels can lead to a large movement at the basket. https://flts.net.au/wp-content/uploads/2019/04/EWP-Catapult-Effect-1.mp4 This can be minimised by travelling slowly over uneven ground with the booms fully lowered and retracted.