A floor spring is a device mainly used for automatically closing and sometimes also for damping the movement of doors. Here's an introduction to its working principle:

1. Hydraulic System Principle (for Hydraulic Floor Springs)

Most floor springs have a hydraulic mechanism. Inside the floor spring, there is a hydraulic cylinder filled with hydraulic fluid. When the door is opened, the movement of the door rotates a shaft that is connected to a piston or a valve mechanism within the hydraulic cylinder.

As the piston moves, it forces the hydraulic fluid to flow through restricted passages or orifices. These restricted paths control the rate of fluid movement. The resistance provided by the hydraulic fluid flowing through these passages slows down the movement of the piston and, consequently, the opening speed of the door.

When the door is released and starts to close, the hydraulic system works in the opposite way. The stored energy in the compressed hydraulic fluid now helps to push the piston back, which in turn rotates the shaft and closes the door at a controlled speed. The hydraulic system also provides a certain amount of damping force to prevent the door from slamming shut.

2. Spring - based Principle (for Some Simple Floor Springs)

In addition to the hydraulic type, there are also floor springs that rely mainly on mechanical springs. When the door is opened, a torsion spring or a tension spring is stretched or twisted. The spring stores elastic potential energy during this process.

When the door is released, the spring tries to return to its original shape due to its elasticity. As it does so, it exerts a force on the door - closing mechanism. This force causes the door to close. The force exerted by the spring can usually be adjusted to some extent to control the closing speed and the force with which the door closes. Some floor springs combine both spring and hydraulic elements to achieve more precise control over the door's movement.