Garage door

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A partially open garage door.

A garage door is a large door on a garage that can either be opened manually or by a garage door opener. Although of many designs, most garage doors are sectional, upward-acting, and self-storing. Garage doors are necessarily large to allow passage of automobiles and/or trucks.

Garage doors can be made out of many materials, but steel, aluminum, wood, and vinyl (polyethylene) are the most popular materials.

A common material for a new garage door is roll formed steel sheet to look like a raised panel wooden door. A design mimicking carriage house doors has become quite popular since about 2002, and many manufacturers clad the exterior of a steel door with composite or vinyl boards to give it the appearance of wood. A more economical alternative for garage doors is steel stamped construction.

An example of sectional-type overhead garage doors manufactured in the style of carriage house doors. They are steel with exterior cladding.

[edit] Description

A typical overhead garage door consists of several panels hinged together that roll along a system of tracks guided by rollers. The weight of the door is balanced by either a torsion spring system or a pair of extension springs.^[1]

[edit] Torsion Spring Lift Mechanism

A torsion spring counterbalance system consists of one or two tightly wound up springs on a steel shaft with cable drums at both ends. The entire apparatus mounts on the header wall above the garage door and has three supports: a center bearing plate with a steel or nylon bearing and two end bearing plates at both ends. The springs themselves consist of the steel wire with a stationary cone at one end and a winding cone at the other end. The stationary cone is attached to the center bearing plate. The winding cone consists of holes every 90 degrees for winding the springs and two set screws to secure the springs to the shaft. Steel counterbalance cables run from the roller brackets at the bottom corners of the door to a notch in the cable drums. When the door is raised, the springs unwind and the stored tension lifts the door by turning the shaft, thus turning the cable drums, wrapping the cables around the grooves on the cable drums. When the door is lowered, the cables unwrap from the drums and the springs are rewound to full tension.^[2]

[edit] Extension Spring Lift Mechanism

An extension spring counterbalance system consists a pair of stretched springs running parallel to the horizontal tracks. The springs lift the door through a system of pulleys and counterbalance cables running from the bottom corner brackets through the pulleys. When the door is raised, the springs contract, thus lifting the door as the tension is released. ^[3]

[edit] Maintenance

In order to keep the garage door operating properly, the entire system should be inspected monthly for any problems. Homeowners should visually inspect the door panels and related hardware for any signs of damage or wear. The panels themselves should be inspected for any major dents, cracks, rust, or rot. The springs, cables, rollers, hinges,tracks, and other hardware should also be inspected for any damage or wear. The counterbalance cables should be checked for any fraying or wear. One should also check for any loose fasteners that can work themselves loose from the vibration of the door during operation.

The balance of the door should be checked monthly also. One should be able to raise and lower the door without any resistence and it should smoothly roll along the tracks and should remain stationary at any point of travel. Usually a door that does not pass these tests is out of balance and should be adjusted. It is usually recommended that only a trained door technician with the proper instructions or a mechanically experienced person adjust or replace the springs.

All moving parts of the door should be lubricated monthly also. The door tracks should never be lubricated since the lubricant will only create a sticky surface on the track that can attract more dirt and grime, resulting in a door that is really difficult to operate. The bearings, hinges, and rollers should be lubricated for proper and safe operation.^[4] Torsion springs should also be lubricated with a light coat of oil to reduce the friction between the coils and to eliminate any noises and to even increase the life of the springs.^[5]

[edit] Safety

A garage door is the largest moving object in a home. An improperly adjusted garage door can pose serious danger when opening and closing. Therefore, one should never stand or walk under a moving garage door. The springs used to counterbalance the weight of the door are always under extreme tension and can cause serious injury if handled improperly.

Garage doors with extension springs should be installed with a restraint cable running through the center of these springs. This is necessary because the springs weaken from the fatigue and stress exerted on the steel wire from opening and closing the door. If an extension spring breaks, it can seriously injure anyone present in the garage or damaging property. The cable running through the center restrains the spring in the event of a failure.

Most overhead garage doors are equipped with torsion springs. Garage doors with torsion springs do not need a safety restraint cable since the torsion shaft running through the springs restrains the spring if it breaks. Torsion springs are superior to extension springs since they are easier to fine tune and balance the weight of the door more evenly.

The bottom roller brackets located at the bottom corners of the door are always under extreme tension since the counterbalance cables are attached to these brackets. Therefore, one should never attempt to remove or loosen the screws that attach these brackets to the door as serious injury can result.^[6] This also applies to other spring hardware such as the setscrews, cable drums, lag screws, center bearing plate, etc.

[edit] References