Fire Department, PCs Laptops Tablets, Tankers

Mid-Mounts Have Greater Visibility And Lower Center Of Gravity

Issue 4 and Volume 12.

mid-mount aerials
Some in the fire service believe mid-mount aerials are the only way to go. With a mid-mount, the operator can pull in to a scene and deploy the aerial without having to back in, a common occurrence with rear-mount aerials. Mid-mount aerials typically have a lower travel height and the weight is generally equalized over the entire wheelbase of the apparatus. (Ferrara Photo)
mid-mount aerial with a platform
A mid-mount aerial with a platform has the advantage of eliminating the bucket overhanging the front of the apparatus, but does add to the overall length of the apparatus. DeKalb County, Ga., recently added two 95-foot Sutphen Monarch aerial platforms to its fleet. The apparatus are built on custom cabs and chassis, powered by Cummins ISM 450 hp engines and Allison 4000EVS and are equipped with Hale Qmax 1,500 gpm pumps and 300-gallon tanks, OnSpot tire chains, Kwik-Raze Magnafire floodlight, SmartPower 8,000-watt generators, Hannay hydraulic hose reels and Akron monitors. (Sutphen Photo)

Which is better, mid-mounts or rear-mount aerials, has been the topic of almost as many debates as what caused the great Chicago Fire of 1871.

How people line up on each side of the issue is usually determined by the aerial apparatus they have in service, by the members of the apparatus committee seeking to make the purchase of a new aerial or by the manufacturer’s representatives, depending on what type of demonstrator they are presently driving around trying to sell.

Both mid-mounted aerials and rear-mounted aerials offer positive and negative features and benefits. Each possesses unique design characteristics and operational capabilities that provide fuel for this continuous debate.

As the aerial sales and product manager for a major manufacturer, the question, mid-mount or rear-mount, is one I hear on a daily basis. Fire departments across North America, seeking to purchase new aerial devices ask themselves the same question many times during the evaluation phase and throughout the process of selecting aerial apparatus.

Travel Height

The mid-mount and rear-mount configurations provide many benefits as well as disadvantages, and they have common functions and features, but I have to speak in favor of the mid-mount aerial ladder and platform.

The most common justification we hear in favor of mid-mount apparatus is overall travel height. This factor has become prevalent due to the average travel height of a rear-mounted aerial apparatus, which reaches 11 feet 11 inches or more, depending on the front and rear suspension of the chassis.

Fire and rescue departments across North America are faced with many obstacles regarding overall apparatus height and are forced to deal with many restrictions or design parameters as a result of low overhead doors on older fire stations, low-lying tree limbs in historic downtown districts, bridge and railroad trellises and low hanging utility and power lines. Most mid-mounted aerial apparatus feature travel heights under 11 feet, giving that style an advantage over rear-mount apparatus, at least in communities where travel heights are concerns.

Driver Obstruction

Damage to a rear-mounted aerial basket as a result of a collision or frontal impact with another object can result in repair or replacement bills over $100,000.

Early in my firefighting career, my department purchased our first aerial apparatus, an 85-foot, rear-mounted ladder tower. This was my first exposure to any type of aerial device. It was pretty cool with its rescue basket mounted at the tip and its incredible sense of security.

It was during the training class that I discovered the first negative attribute of a rear-mounted aerial device – driver obstruction.

Much to my amazement almost half the windshield was blocked by the mammoth rescue basket. As I prepared myself to tackle this beast of a vehicle, I quickly discovered that driving it was dramatically different and more difficult than any of the engines or rescue units in our fleet.

Center Of Gravity

After several test drives with the instructor and my deputy chief, I soon realized this unit came with a few challenges none of us had expected.

Mid-mounted aerial devices provide obstruction-free visibility making the overall apparatus safer to operate and, with the massive aerial device mid-ship mounted, the vehicle’s center of gravity is greatly improved resulting in better handling and safer driving.

There has been much discussion about the maneuverability of mid-mounted aerial ladders and platforms. The term “tail-whip” refers to the amount of rear tail swing associated with mid-mounted aerial apparatus during turns.

There is some merit to this discussion. The overall length of most mid-mounted aerial apparatus exceeds 45 feet with some designs in excess of  50 feet. The 240-inch or greater wheelbase also factors into the equation. However, this “tail-whip” condition can be overcome with adequate driver training and proper driving techniques.

Older, larger apparatus with long wheelbases required the driver to swing-out to the right before making left hand turns. This practice is  no longer as critical due to engineering improvements and the innovation of front axle technology and  steering geometry.

More Forgiving

The steering systems available today feature incredible cramp angles and state-of-the-art steering components that result in tighter turning radiuses and optimum maneuverability for vehicles of this size, weight and length.

Mid-mount aerial devices also provide many enhancements over rear-mounted units during fireground operations. The feedback received from mid-mount users is that mid-mounts are more forgiving when it comes to apparatus placement at the fire scene.

That opinion is derived from the fact that the turntable of the mid-mount aerial has access and deployment zones that are greatly enhanced over rear-mounted vehicles. This enhancement also provides for quicker deployment of the aerial after completion of stabilizer set-up.

Scrub Areas

Mid-mounted aerial devices also provide a more compact and condensed scrub area, or the area required to set the platform basket directly on the ground. Some mid-mount aerials and platforms offer scrub areas that are less than 30 feet, providing the ability to operate the aerial device up to 12 degrees below grade without having to extend the aerial out. This feature allows for the safe, easy loading of equipment and personnel while on the ground versus carrying equipment down the ladder alley to access the basket.

There will always be much debate over the mid-mount versus rear-mount issue. However, I am happy to say the many enhancements and improvements in aerial apparatus over the last 20 years has dramatically improved the safety of firefighters who are assigned to aerial ladders and ladder towers.

I hope I’ve provided some useful and helpful information to provide the readers and purchasers of aerial apparatus some insight into the different types of apparatus and the pros and cons associated with each.

Editor’s Note: Joel Domangue is a 25-year veteran of the fire service. He began his career as a fire chief of a volunteer department in south Louisiana in the early 1980s. He later became part of the management team at Ferrarra Fire Apparatus. He has been a member of the Fire Apparatus Manufacturers Association (FAMA), the International Association of Fire Chiefs (IAFC), the International Society of Fire Service Instructors and is currently the aerial sales and product manager at Ferrara in Holden, La.

More Fire Apparatus Current Issue Articles
More Fire Apparatus Archives Issue Articles