“The Bendy Straw” Tractor Drawn Aerials and their spot in the fire service

About

Tractor-drawn aerials are one of the most unique and versatile fire apparatus in the national fire service. The tractor-drawn aerial is the most maneuverable aerial apparatus available, even though it’s much longer than a straight-frame aerial. They can navigate around obstacles and get in and out of tighter, congested areas. This gives it the ability to steer into locations that a straight frame aerial is unable to navigate. This capability provides the opportunity to get closer to a structure for firefighter access or victim rescue. In certain locations, a straight-frame aerial would require a three-point turn to make access or would simply have to park and have the crew walk their equipment to the fire location. It can be broken down into three different parts: the tractor, trailer, and tiller. “Tillers” are highly maneuverable because of the fifth wheel articulation and the ability to steer the rear of the trailer around obstacles.  Because of its maneuverability, the turntable on a tractor-drawn aerial can be manipulated closer to buildings compared to a straight-frame aerial. The tractor-drawn aerial can navigate into urban developments with tight access to apartment complexes, condos, offices, and college campuses. Tractor-drawn aerials accommodate a larger number of ground ladders than straight-frame aerials. Because tractor-drawn aerials are mid-mount aerials, the structural components for the turntable are located towards the front of the apparatus, thus providing a larger space for ground ladders in the back of the trailer. 

History

These apparatuses have a long history, dating back to the 1800's and are recognized as the most famous piece of fire machinery when people think of the iconic firetruck. No other fire apparatus driving down the road provides a big amount of tradition, as much childlike wonder as a tractor-drawn aerial.  

Cab options on TDA’s

Jackknife warning: 

Because tractor-drawn aerials can jackknife, there are warning systems for both the driver and tiller operator to alert them that they are approaching a jackknife position. When the system senses that the tractor and trailer are at a preset angle to each other, the alarm will activate. The warning system signals the driver and tiller operator with both an audible and visual alarm. The jackknife visual alarm is a light that is located in the cab and will illuminate when the alarm is triggered. When driving in tight, diminished clearance situations, the driver should be concentrating heavily on their surroundings and may not be aware that the apparatus is close to the jackknife position. If the light is not easily viewable and the driver is focused on the circumstances around them, they may not see that the light has activated. The jackknife audible alarm is just one of many audible alarms on a tractor-drawn aerial. Actions that will produce an audible alarm are things like compartment open, apparatus doors open, seatbelt alarm, buzzer system for the driver and tillerman.  It is essential during the design phase to specify that the jackknife audible alarm remains a separate sound from the rest of the warning alarms.

Driver Intercom Systems:

While most modern fire apparatus contain headsets inside the cab for communication while responding, tractor-drawn aerials also have these, but they have headsets in the cab as well as in the tiller. Before headsets were used, there were intercom systems. Before intercom systems, the driver and tiller operator used a buzzer system to communicate. Tractor-drawn aerials still come equipped with the buzzer system, though the driver/tiller operator intercom system is not a standard item and requires specifying with the manufacturer. Today’s intercom system is designed as a two-way communication system between both driver and tiller operator; they are hardwired from the tractor to the trailer.  The intercom is a backup system to allow the driver and tiller operator to speak with each other if the headsets are not working. The intercom system is designed for challenging acoustic environments and to provide clear communication within the fire apparatus.  These intercom systems are the same system that allows the driver at the turntable controls to talk to the firefighter at the tip of the aerial. 

Turntable steps:

There are a variety of different styles and types of steps leading up to the turntable, based on the manufacturer you choose. Depending on the manufacturer, you will have the capability of choosing how many steps you desire to help with the transition on and off the turntable. You may also find manufacturers that provide a footstep that sits under the main body of the steps leading up to the turntable. This step can either be a stationary step or a fold-down step below the main group of steps. All steps will have handrails to help firefighters up and down the steps. You will generally be facing backwards as you leave the turntable to transition onto the steps. Handrail placement is important during this function as your hands naturally look for a place to stabilize during the shift in movement. 

Outside tools on the tractor:

Because of the size of a tractor-drawn aerial and the fact that it articulates, unique areas are available to attach tools to the outside of the apparatus. There is generally plenty of space behind the tractor and under the turntable to fasten tools or equipment such as a set of irons, New York hooks, Halligans, pump cans, battering rams, wheel chocks, traffic cones, or even a folding ladder.

Tractor Bumper: 

Extended bumpers have become common with today’s fire apparatus; however, an extended bumper on a tractor-drawn aerial can hurt maneuverability. Aerial apparatus that are equipped with extended bumpers can serve many purposes depending on each department’s needs or requirements. These bumpers can provide equipment or tool storage, such as hydraulic reels, a heavy-duty winch, extrication tools, ropes, etc. Of course, one can’t forget one of the favorite pastimes for the national fire service, which is to use these bumpers as a seat while hanging out at the fire station or on scene after a call. With today’s modern tractor-drawn aerial reaching sixty feet and beyond, adding a large bumper on the front of the tractor can inhibit the turning radius in tight situations because an extended bumper increases the overall length of the apparatus. The gallery below features examples of tractor-drawn aerial front bumpers that do not limit overall maneuverability. 

Back windows:

Providing windows on the back of the tractor can be extremely helpful for the driver when backing up, in the driver's blind spot, and should be an important consideration. These windows can also give an additional view for the firefighters sitting in the jump seats behind the driver and officer. Firefighters can provide the driver with valuable information by having access to view the area directly behind the cab. Windows for the back of the tractor can come in different shapes and sizes, depending on the available space on the back of the cab wall.

Trailer options on TDA’s: 

Trailer profile: When navigating the trailer through tight clearance issues, you gain an advantage if the back of the trailer’s profile is reduced. By designing the back of the trailer to be narrower than the rest of the trailer, the trailer's silhouette becomes smaller as you pass through constricted areas. Because of the length and size of a tractor-drawn aerial, deciding not to add compartments to the end of the trailer can pay dividends when the trailer slides through locations that would otherwise be too tight. 

Aerial Tip:

The tip of the aerial ladder on a tractor-drawn aerial sits directly in front of the tiller operator when bedded in its cradle. Aerial ladders routinely have scene lights, intercom systems, brackets, controls, etc. attached to the tip. These items can block or obstruct the view of the tiller operator when they are in the tiller cab, trying to maneuver the trailer. 

Angle Of Departure: 

The angle of departure of any vehicle is the angle between the ground and a line running from a rear tire to the lowest-hanging component directly behind it, usually the rear bumper. In Seattle, where I live, or in places like San Francisco, there are topography challenges from an overabundance of hills we must navigate with the tractor-drawn aerial apparatus. Because of the length of a tractor-drawn aerial and the steepness of some hills, the angle of departure must be a consideration. Manufacturers can account for the angle of departure by simply notching out the back bottom part of the trailer. This provides more space between the bottom of the trailer and the ground, reducing the likelihood of the trailer hitting the ground as it drives up a steep hill.

Compartments Under The Trailer:

Sometimes departments will design their tractor-drawn aerial with extra compartments under their trailer for extra storage space, for such things as plywood, extra cribbing, etc. 

Compartments on top of the trailer: 

Sometimes, placing a compartment on top of the trailer (if room is available) can be a great place to store additional equipment. This will depend on what manufacturer you use, the amount of available space under the aerial, and the space next to the aerial. A coffin box is a compartment that sits on top of the trailer next to one or both sides of the aerial. It is generally a pretty deep compartment that is opened while standing on top of the trailer or from the side. This box can be walked on as you move along the top of the trailer.  The coffin box is a great place to store extra cribbing or equipment for hooking up the waterway if the aerial is not pre-plumbed.

Trailer Compartment Height:

In today’s fire service, truck companies are required to carry a large complement of equipment, and compartment space becomes a premium. One of the main considerations for operating a tractor-drawn aerial is the sheer amount of compartment space available.  Departments can become compartment happy and design the trailer with tall compartments down the body of the trailer to accommodate all their equipment needs. Requiring high-sided compartments towards the rear of the trailer can cause visual obstructions for the tiller operator. Because the tiller cab sits so high on the trailer, the tiller operator will always have some blind spots down the sides of the trailer. When designing compartment space, reducing the high-side compartments on the rear of the trailer should be a major consideration. This will give the tiller operator better sight lines when maneuvering the trailer.

Tiller Options

Tiller doors: 

Three different types of tiller doors are offered by manufacturers. Sliding, Hinged, and Accordion. Some manufacturers provide different tiller door choices, and some manufacturers endorse their standard tiller door unless you otherwise specify. These doors come with a range of different window styles, depending on what manufacturer you choose, including bubble windows.

Bubble Windows: 

Some tractor-drawn aerials are built with bubble windows in the tiller doors. These windows are designed to increase the field of vision for the tiller operator without having them open the door or window to look down the sides of the apparatus. Tiller cabs are designed to be narrower, so it’s not difficult for the tiller operator to steer and look out the window at the same time. Generally, you have to specify to the manufacturer that you want this option for the tiller door windows. The need to look down the side of the apparatus is a common practice, and using these types of windows can be extremely helpful during cold or inclement weather. The tiller operator is protected while simply popping their head out into the bubble to get a better view.

“Dead-Man” Switch:

The dead-man switch is a device intended to act as an interlock system to prevent the driver from driving off without a tiller operator in the tiller seat. The dead-man switch is generally a foot-operated pedal that must be depressed to allow the apparatus to move. Although this switch is commonly referred to as the dead-man switch, it technically does not function as one, but rather more as an interlock system. The driver cannot shift the transmission into drive/reverse until the tiller operator has activated the foot pedal switch. Once the apparatus is in drive/reverse, the tiller operator is now able to take their foot off the pedal. Anytime the transmission is placed back into neutral, it will require the tiller operator to press on the pedal to again activate the transmission. 

Tiller Sunroof: 

Tiller cab windows are very important for the tiller operator as they maneuver the trailer throughout their city. A sunroof in the tiller cab provides additional viewing capacity for the tiller operator as well as more ventilation. Generally, this option is something that you would need to specify with the manufacturer. 

Pros:

• More maneuverable than a straight-frame aerial, even though the tractor-drawn aerial is longer than a straight-frame apparatus

• More maneuverable responding in and around narrow streets, traffic circles/calming circles, parked cars, cul-de-sacs, and traffic projects.

• Faster setup time

• Even though the tractor-drawn aerial is a larger apparatus, the overall weight of the apparatus is approximately 15,000 pounds lighter than an aerial platform.

• Because the tiller operator is much higher than the driver, they can provide a second set of excellent eyes for traffic at intersections. Seeing up ahead of the traffic, in front of them, Positioning the turntable, Wires or other obstacles

• Typical height of a tractor drawn aerial is around 11'2”, where aerial platforms can be from 11' 11” to 12 '2".

Cons:

• Increased overall length of the apparatus (56’ up to 65’)

• Must have trained driver/ tiller operators.

• Requires having two drivers, which can be a burden on departments that rely on moving personnel around to fill staffing needs.

• Tractor-drawn aerials can be more expensive depending on the type of aerial apparatus you purchase.

Manufactures: 

• Pierce MFG • Ascendant 107' tractor-drawn aerial, Ascendant 101’ tractor-drawn aerial, 

• E-One • HP100 Super Tiller,  110’ Tractor-drawn Aerial

• Spartan • 100’ Tractor Drawn Aerial

• KME • 101’ Tractor Drawn Aerial

• Rosenbauer • 100’ Tractor Drawn Aerial 

Photo 1: Elizabeth Fire Department (Union County, NJ) Ladder 2 is this 2016 Pierce Arrow XT 6710 95' tractor-drawn with a 1997 LTI tiller and ladder.

Photo 2: Philadelphia Fire Department (Philadelphia County, Pennsylvania) Ladder 10 is this 2024 Spartan ER Metro Star MFD 100' LTC tractor-drawn aerial.

Photo 3: Holyoke Fire Department (Hampden County, Massachusetts) Former Ladder, is this 1972 Maxim S 0/0/100' tractor-drawn aerial that is now privately owned.