Doors - Sectional Steel Overview

The most common type of commercial door is the sectional steel door. Called sectional steel because the doors are made up of pieces (sections) of thin steel of varying lengths (depending on the opening size) and heights (usually 24” high) again depending on the opening size. The sections are attached to one another with hinges, roller fixtures and steel rollers (usually 2” diameter on a steel shaft). The rollers run up and down along a track that mounts to the wall and goes from the floor to the shaft ending at a steel bumper spring that stops the door from going to high. The door operates by using one or more torsion springs set onto a steel shaft. A torsion spring is a spring that works by torsion or twisting; that is, a flexible object that stores mechanical energy when it is twisted. The amount of force (torque) it exerts is proportional to the amount it is twisted. If twisted to tight the door will go up too fast and hard. If twisted to loose the door will be too heavy to go or stay up. The ends of the shaft have a drum or cone mounted to it. Aircraft cables are wrapped around the drum and then attached to the bottom roller fixture. As the door is raised, the cables wrap around the drums as the shaft turns. As the door is lowered, the cables unwrap from the drums as the shaft turns in the opposite direction. Sectional steel doors can be ordered as manual (push pull), chain hoist or electric operator (motor) operation. Doors must be properly maintained and inspected as they can injure or kill anyone caught under a falling door. Doors that are not adjusted properly can creep down into the opening and be damaged by a forkilft or product. This will not only damage the door but could potentially cause injury. Proper maintenance and inspection is vital to having a safe and efficient working environment.

Doors - Sectional Steel