Introduction to Cantilever Gates:
A cantilever gate
is unique in that it 'cantilevers' itself to close an opening while being supported from
only one end. Cantilever gates move in a linear motion, or straight line, without
requiring any lateral space as a swing gate would require. Due to its cantilevered design,
these gates are typically built larger in width than the opening they are designed to
close; this allows a portion of the gate to remain outside of the opening, often
unobtrusively behind the adjacent fence line. This portion of the gate is called the
The gate counter balanceshould
be 1/2 the length of the gate opening. Minimum counter balance should be 4' long. If
an automatic operator is to be installed, the counter balance may need to be longer so the
operator can 'pull' the gate shut by the rear of the counter balance. Always choose the
operator and gate before construction begins.
Traditionally, a cantilever gate is 'sandwiched' between two
top rollers and two bottom
rollers and mounted on two posts as shown above. A leading edge wheel is not required in
most cases due to its cantilevered design. Another type of hardware system other than gate
rollers may be employed. One such system employs a track which is mounted near the top of
the gate between roller posts. The gate hangs suspended from the track with trolleys.
There are guide rollers mounted to the bottom of the roller posts which prevent the bottom
portion of the gate from being pulled away from the posts.
A cantilever gate should not be confused with other types of
slide gates such as 'V-groove type track gates', 'overhead gates', or 'rolling gates' as
they are often called. These type gates have a track in the gate opening and/or a leading
edge wheel attached to the latch side of the gate which rides on the ground. A V-groove
type track gate has an inverted piece of angle iron imbedded in the drive on which a
specially notched wheel
attached to the gate frame can ride. An overhead gate usually hangs suspended by trolleys with steel bracing,
truss rods, and truss cables from an overhead I-beam which extends over the
gate opening. Lastly, a rolling
gate typically has a pipe track mounted to the adjacent fence on which the back
portion of the gate may ride with a pipe track rear wheel. A leading edge wheel is mounted to the latch
side of the gate which simply rolls on the ground.
Advantages of the Cantilever Gate System:
Cantilever gates have many advantages over swing gate systems:
1. Cantilever gates may use less space than a swing gate system.
Single cantilever gates move in one direction, often directly parallel to an existing
fence line. This efficient use of space makes a cantilever gate an ideal choice when
designing a property's perimeter fence and security system.
2. Cantilever gates may be easier to safeguard than swing gates
when automating. Safety devices are strongly recommended, if not required, when automating
a gate. Such safety devices may include safety photobeams, safety edges, and loops and
loop detectors. Safety devices are designed and installed to protect against the gate
closing on a vehicle. Due to the linear movement of a sliding cantilever gate, the path of
the gate is limited in comparison to a swing gate which swings in an arc approximately 90
3. Cantilever gates may be less expensive to automate than swing
gates. In some instances, when a double swing gate and a single cantilever gate is to be
considered, a single cantilever gate will be less expensive to automate since it requires
only one gate operator instead of two.
4. Cantilever gates may require less maintenance than swing gates.
Cantilever gates may be installed with nylon cantilever rollers with sealed bearings and
nylon roller covers. These rollers do not require greasing and the nylon
roller itself and cover will not rust. Further, cantilever rollers will
install to posts with bolts which are easy to adjust at a later date if
necessary. The brackets which typically connect a gate operator to the gate also are
usually installed with bolts that will be easy to adjust later.
Conversely, swing gates often have hinges which require repeated greasing. These hinges
will also often be welded to the gate post and gate making them difficult to adjust if
necessary. Lastly, consider snow removal in northern locations. The single path a
cantilever gate travels will often be easier to keep clean of obstructions
compared with a swing gate and it's wide swing.
5. Cantilever gates are aesthically appealing. The smart
appearance, efficient design, and craftsmanship in a cantilever gate is sure to impress
owners, visitors, and customers visiting the property.
The vertical bracing should be spaced 4 to 6' apart. If 2-1/2" sch. 40 pipe or comparable is used
5' spacing is adequate. The rollers ride on the horizontal outside frame. Support for the
top and bottom of the frame is essential. Only the 'opening' portion of the gate is
stretched with chain link, or need fascia applied. The counterbalance usually slides
behind a fence line and is designed for structural integrity only.
Post sizes are important. In general, chain link
cantilever gates require 3" O.D. (outside diameter) roller posts for widths up to 10'
opening size. Use 4" O.D. posts up to 20' and 6 5/8" O.D. posts up to 32'. These
specifications are for 6' high gates and shorter. For taller gates increase post
sizes at each step and use 8 5/8" O.D. posts for 32' gates.
Concrete footers need to be
significant. 18" diameter x 42" deep is recommended for 3-4" O.D. posts,
24" diameter x 42" for 6 5/8" O.D. posts and 30" diameter x
48" for 8 5/8" O.D. posts. Increase bottom diameters 6"; creating a bell
shaped hole. The up and down stress with these type gates will 'work' even the largest
posts out of the ground. Poor soil conditions, such as sand, will require larger footers.