Scissors mechanism

[2] Extension is achieved by applying pressure to the outside of a set of supports located at one end of the mechanism, elongating the crossing pattern.

A power source is turned on resulting in the flow of hydraulic fluid or air (in the case of a pneumatic lift) in the cylinder.

The hydraulic cylinder thrust outward for upraised movement and that in turn lead the scissor legs to spread and raise the platform table upwards.

To lower the lift, the operator uses a down valve to release hydraulic fluid or pneumatic pressure, which causes the scissor legs to retract.

Modern low-profile computer keyboards make an extensive use of it as well, installing each key on a scissor support to ensure their smooth vertical movement, allowing the use of a cheap and reliable rubber dome contact set, instead of expensive and complex array of mechanical switches.