Tips for determining the type of aerial vehicle stabilizer

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The downside to H-style sockets, such as the ones found on this Sutphen SPH-100, is that they can take up so much space that they limit compartment space.

Photos of Mark Miller

When analyzing your aerial gear needs, you should determine the type, configuration, and amount of stabilizers that will work in your community. As with aerial construction, the types of stabilizers vary considerably from industry to industry.

The three most common types of stabilizers are A-frame, H-frame, and under-suspension cylinders. Executioners and downriggers are also prevalent, especially with mid-mount aerial devices. Each has its pros and cons, and it’s up to the buyer to determine what will be best suited to the machine’s racing area.

The stabilizer shoe, cylinder penetration and short lift capacities are also specification items that require the attention of the purchasing committee.

The options

A-frame jacks are reciprocating jacks that typically only protrude a few feet from the side of the unit. They can be used as a sole stabilization system for the antenna or in conjunction with another style of stabilizer. These jacks are quick to deploy and take up very little space on the fireplace. Although they are more common in smaller aerial devices, such as raised booms and articulated platforms, they are also used on tractor-towed antennas which have lighter peak loads and often in conjunction with front of unit with H style rear jacks.

The main disadvantage of A-frame stabilizers is that they have limited application for antennas that have a longer range when not used with other types of stabilizers.

H-style jacks are perhaps the most common lifting system used in fire departments for mid-mount and rear-mount overhead devices. Depending on the antenna type, tip length and weight of your service, you can specify H-style jacks in two- and four-cylinder configurations.

The industry also varies widely in the extended footprint of H-style jacks, which is currently 12 to 19 feet or more. In four-cylinder configurations, larger stabilizer footprints can take up valuable space on the fire field.

Jack mounting locations also differ among device manufacturers. Two-cylinder stabilizer systems can be mounted in the middle or rear of the rear wheels.

The downside to H-style sockets, such as the ones found on this Sutphen SPH-100, is that they can take up so much space that they limit compartment space.The downside to H-style sockets, such as the ones found on this Sutphen SPH-100, is that they can take up so much space that they limit compartment space.Photos of Mark MillerThe downside to H-style jacks is that they can take up a significant amount of valuable space in the compartment. To compensate for the loss, departments often choose to extend the body of the device to add space, thereby increasing the overall length of the device. Additionally, when used on mid-mount aerial devices, the H-style plugs may prevent the aerial device from being used at or below ground level because the aerial device cannot pivot on the floor. taken.

Under-suspended cylinders are also popular among device manufacturers. These cylinders have a lower center of gravity than the cylinder types and allow compartments to be placed above the cylinder in the body. Suspended cylinders are available in two and four cylinder configurations, depending on the type and length of the overhead device. These jacks can have a reach as small as 11 feet when fully extended and can reach 16 feet.

Under-suspended jacks, as seen here on a Sutphen SL-75, deploy extremely quickly and in a small footprint.Under-suspended jacks, as seen here on a Sutphen SL-75, deploy extremely quickly and in a small footprint.In two-cylinder systems, suspended cylinders are typically mounted in the mid-position for mid-mounted aerial devices.

The under-suspended cylinders deploy extremely quickly and in a small footprint. This is perhaps their biggest advantage.

Note: Not all manufacturers allow users to use under-suspended cylinder systems on short cylinders. This can be problematic in areas that have tight developments.

Tormentors are mounted vertically amidships and fold into their operating position, as used in the iconic Seagrave Aerialscope. These stabilizers have an operating width of up to 20 feet, 6 inches for 95 foot models and are used in conjunction with winches to provide additional frame stabilization.

The major benefit of using the tormentor setup: A tower ladder that includes it has unhindered access to the front stabilizer for ground level or below ground level operations. This ability makes her an invaluable resource in the fiery terrain. One drawback of this setup: Because the tormentor must pivot down into its operating position, if you have to short-jack the device, you cannot get the short-ram side to the ground, unlike other types of stabilizers. .

Finally, downriggers are used in conjunction with other types of stabilizers and are typically mounted on the front bumper extension and / or the rear of the rear doubles. As the name suggests, downriggers protrude directly from the device to provide chassis stabilization by capturing the vehicle’s suspension. Downriggers are most commonly used on mid-mount overhead aircraft; However, they are also becoming popular on rear mounted aerial devices. Some manufacturers use winches instead of A-frame stabilizers on the front of rear-mounted overhead devices when used with other types of stabilizers.

A major advantage of using downriggers with other types of stabilizers is that the downriggers do not take up additional space on the fire field. One downside is that they can take up a valuable front bumper and storage compartment.

Footwear

Another option that needs to be considered is the air intake shoe. Jack shoes vary widely from manufacturer to manufacturer and have a direct correlation with the need to place a jack stabilizer pad under each stabilizer, which is time consuming. Some manufacturers offer stabilizer pads integrated with the stabilizer shoe to completely eliminate the need for a separate stabilizer cylinder stabilizer pad.

Even if NFPA 1901: Standard for Automotive Fire Apparatus indicates that the ground contact zone for each stabilizer “shall be such that a unit pressure not exceeding 75 psi (500 kPa) will be exerted on the ground contact zone when the apparatus is loaded to its maximum weight in service and the antenna being rated at the device in any position permitted by the manufacturer ”, he also notes that“ a stabilizer pad may be used to achieve 75 psi (500 kPa) or less ”.

Shim can help navigate radius borders and square borders.Shim can help navigate radius borders and square borders.Making sure you have adequate rigging on your aerial ladder can help provide additional stabilization when working on paved roads. By placing several 4×4 inch pieces of shim under your stabilization pad, you can ensure that you won’t lose cylinder pressure as you adjust your antenna. In addition, the inlay can be used to help you navigate both rounded and square edging and to eliminate the risk of damaging your jack shoe or stabilizer pad.

Jack’s penetration is yet another critical consideration for communities that have extreme topography. Manufacturers usually offer several different options for cylinder penetration to allow you to level the turntable within usable limits during grade. Several manufacturers offer deep penetration jacks that can provide leveling over 10 degrees both front to back and side to side. One downside to deep penetration H-type jacks is that you will likely lose the ability to have compartments above the stabilizer. In many communities, this is seen as a necessary compromise.

A disadvantage of deep penetration jacks is the likely loss of compartments above the stabilizer.A disadvantage of deep penetration jacks is the likely loss of compartments above the stabilizer.Short-jacking

The ability to bypass an aerial device on the non-functional side can reduce the space the vehicle uses on the fire field. It can also be essential in tighter developments or for aircraft arriving later. Often times you have to pull the aerial device as far as possible across the street to knock down the antenna base section to the lower floors. Many 100 foot rear mount antennas have a retracted boom length of 34 feet or more to the side. Short lifting on the non-functional side increases the brushing area of ​​overhead ladders and tower ladders.

Not all lifting systems can be fitted with short jacks, so it is important that you know the operating area of ​​the device to see what will work for you. In addition, some short-jack systems require two people to lift the main antenna out of the vehicle bed. This can be problematic in a fire scene where personnel are performing their assigned task. To increase efficiency, you can specify short grip capacities for one person.


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