What is the mechanism of scissor lift?

The scissor lift mechanism/scissor lift working principle relies on a set of cross-braced arms that move up or down to raise or lower a load-bearing platform attached to the top of the assembly. The power source needed to extend or retract the scissor lift mechanism for the up and down movement would depend on the platform size, operating height, and load handling of the lifting unit. 

How does a scissor lift mechanism work in practice? The specific mechanics will depend upon its power source, which can be hydraulic, pneumatic, electric, diesel, etc. However it is powered, the basic principle of operation remains the same. So, using a hydraulic scissor lift mechanism as an example, the sequence is this: 

1.The scissor lift operator turns on the power source. Using a valve to control the flow of fluid or air starts to fill the cylinder(s) with hydraulic fluid (or compressed air in a pneumatic system).

2.The scissor lift control system moves the hydraulic fluid or compressed air from the reservoir to the operating cylinders.

3.The hydraulic cylinder pushes outwards for upward movement and causes the scissor legs to push apart, raising the platform.

4.To lower the scissor lift mechanism, the operator uses a down valve to release the hydraulic fluid or reduce the pneumatic pressure level in the cylinder by returning it back to the reservoir, causing the scissor legs to retract.