Door and board lifters are known as first-class levers, allowing you to lift and hold a heavy sheet of material a few centimetres off the ground. They reduce the effort required to support rigid sheets.
The lifter’s lift shelf fits under the sheet and your foot pushes on the footpad to lift the sheet. Once lifted to a required height some lifters can lock in place; others will rely on you keeping your foot steady as you work.
How does a first-class lever work?
Levers are simple machines which are used to amplify an input effort, so the output is a greater force. There are three types of lever: first-class, second-class, and third-class. They have different positions for the input force, the output force, and pivot point (or fulcrum). A first-class lever has the pivot point between the input and output forces.
The efficiency of a lever is known as its “mechanical advantage”. The mechanical advantage of a first-class lever is increased by extending the distance from the input point to the pivot point and reducing the distance between the output point and pivot point, which is reflected in the design of most door and board lifters.