Understanding Box Framed Cantilever Gates
America’s Gate Company has been manufacturing aluminum box framed cantilever gates for decades. Box framed cantilever gates serve a unique purpose when a standard single or double track aluminum cantilever gate fails to adequately support a stated wind load or simply flexes too much. When the gate opening exceeds 30’, you may want to consider a box framed cantilever gate. Beyond the opening width there are several factors you will want to consider in your decision to upgrade to this more developed gate type.
- Wind load – Is the gate in a unique position where it may incur head-on or sheer winds. In wide open terrain such as an airfield, headwinds or wind shear blow uninterrupted across the field causing unusually above average wind loading. If the gate is placed at the end of a tunnel effect where winds are forced to compress between buildings or objects and then hit the gate head-on; shear winds will have an exponential effect on the amount of wind load placed on the gate. Under these conditions, a standard cantilever gate may flex too much during the closing cycle to fall within the receiver or catch at the full closed position.
- Gate surface – Standard commercial chain link has a 98% open calculation. Standard cantilever gates are designed under this consideration. When designers place signage, perforated or solid surface screening on the face of a cantilever gate, the open percentage calculation will vary significantly and adversely place a considerable amount of load on the gate under even below average wind speeds.
- Gate height – The taller the structure the exponentially greater the wind load. Shear winds are forced to compress when attempting to climb over structures where there is no movement or opening at the ground level. This causes a considerable amount of loading at the top of the structure. Standard 6’ tall cantilever gates may not be adversely affected by this type of loading. However, as the gate height rises to heights ranging from 8’ to 16’, the impact is considerable even with standard chain link fabric applied to the face of the gate.
- Sustainability – Standard chain link gates may satisfactorily function in applications with unusually high wind loading. However, these gates and the related gate hardware may also quickly wear out and fail as the gate track bends and warps under wind loading during the open and closing cycle. Wind loading on a standard cantilever gate forces the gate to place a great deal of pressure on the gate roller assemblies in the gate track. This may cause the wheels of the gate trucks to eventually wear a groove in the track or cause the trucks to wear out the bearing assemblies. Box framed cantilever gates are very rigid and though there is still a great deal of load placed on the rollers; the gate track remains straight and true through travel.
For all practical purposes, a box framed cantilever gate is actually two standard single-track cantilever gates placed approximately 24” apart and connected with a series of trusses. Many people associate a box framed cantilever gate with a box kite as both look and function similar. Another common comparison are the large box truss systems that envelope pedestrian walkways or overpasses. A box truss is a common engineered shape. Its purpose is to provide support or rigidity both vertically and horizontally. America’s Gate Company has been engineering and building box framed cantilever gates for decades. The team of designers and fabricators firmly grasp the engineering concepts necessary to adequately design a box framed cantilever gate for a specific size opening, height, weight and gate surface material.
The common engineering principles critical to any box framed cantilever gate are its diagonal trusses and material composition. A box framed cantilever gate is nothing more than a series of horizontal and vertical trusses. The shape of these trusses, in particular the angle of the diagonal truss(s) to the frame of the truss, is the critical engineering design element that ultimately determines the amount of load applied to the truss before it fails. The material composition is critical in whether a compression or suspension-type load is placed on the diagonal truss. A compression type load will require a solid and rigid material that cannot be easily compressed or compromised. A suspension type load is best managed with an adjustable cable-type truss where the resistance may be adjusted to account for gravity or wind load.
The design is only the beginning.
America’s Gate Company has a team of certified AWS D1.2 G6 welders. Our talented welders and fabricators are more than capable of deciphering complicated designs, understanding fabrication specific welding procedures and maintaining our quality control standards. Every weld joint has a specific weld procedure relevant to the type of materials, thickness and relationship between the two pieces being joined together. Our fabricators do more than just weld aluminum. We are certified professionals following a strict set of guidelines and quality control procedures.
Box framed cantilever gates are generally big! It is a monumental task to get these gates to you. In spite of this feat, the greater act is the installation. America’s Gate Company appreciates these challenges in meeting your security needs. We will not only design, build and deliver your gate, we will install it. Unlike any other major gate manufacturer, we offer installation. America’s Gate Company has teams of installation experts who have been certified in the installation of cantilever gates and installed hundreds of these gates across the United States. We will deliver, unload and install your gate from beginning to end. Our installation crews will set the gate support posts, install the gate, install the gate surface materials and support the installation of your automated access controls.