Rear vs. Midship Mount

FA Viewpoints
 

Editor’s Note: Asking about midmount vs. rear-mount aerials can often create passionate debates. However, deciding on which to purchase should be based on the tactics you wish to achieve and the unique characteristics of your first due and surrounding areas. This month, we asked Editorial Advisory Board members Bill Adams and Ricky Riley to comment on midmount and rear-mount aerials.

 

Ricky Riley

Looking at both types of apparatus configurations, the decision for the purchase is truly based on the operational and geographic needs of your department. The midship-mount aerial is a small niche in the production of aerial ladder sales across the country. But, that does not mean that it does not have a place in the market or in a particular department. The standard rear-mount aerial is certainly the majority of the straight ladder market and has certain features that make it fit for most departments looking for a straight truck.

Midship-Mounted aerials

In a midship-mounted aerial, the turntable usually is right behind the cab, situating the device low on the frame rails and closer to the ground than the rear-mount aerial. Selecting a midship-mount does offer some tactical advantages for the department. One of these is a driving feel on the apparatus—by having this weight lower on the chassis and more centered, it will have less of a sway when taking corners. This is the feel that drivers experience with rear-mount aerials when the weight of the turntable and aerial is more elevated, situated behind the rear axles. That much weight moving in a direction opposite the turn can have a dramatic feel for the driver depending on the speed of the turn. With the lower turntable of the midship mount, this is reduced and creates less of an issue for drivers. With the advancement of driving technology and the use of electronic stability control, this sway is greatly reduced with the reduction of acceleration capabilities when the apparatus feels the turning speed affecting its stability.

Usually one of the main reasons for the midship-mount is a height restriction in older firehouses. With the device mounted low behind the cab, the overall height is greatly reduced. This turntable positioning also offers a tactical advantage for the ladder chauffeurs. These older firehouses with height restrictions are normally in older cities with very tight street layout and with numerous wires in the front and rear of the structures. The lower turntables can allow the operator to position the rig underneath the wires, rather than over top of them, which is how we would normally use the rear-mount aerial.

Another driving item with this type of rig is the rear swing out. A lot of the aerial and compartments are behind the rear axle, more or less hanging off the back. When navigating streets, the driver will need to be especially conscious of the rear end of the truck and the swing when taking corners. These vehicles, along with midship mount towers, require the driver to pay special attention to this as to not incur damage when taking these corners—especially in tight congested cities or towns.

The midship-mounted aerial’s turntable and ladder positioning greatly reduces compartment storage. Depending on the number of duties that your aerial device is required to accomplish—not just on firegrounds but on all types of emergencies—this may require your department to carry an enhanced amount of equipment that will demand more compartment room and options to carry that equipment. With the device taking up a lot of this room, the chance for full-height compartments and through compartments is not an option for the midship-mounted device.

Rear-Mounted aerials

The rear-mounted aerial device is by far the norm when getting a straight aerial ladder. Like the midship-mounted aerial, the device itself is available with a medium-duty ladder or a heavy-duty ladder. And, these ladders have their turntables mounted above the body compartments and ladder storage in the torque box, creating somewhat of a high center of gravity because of the sheer weight of the turntable itself and the ladder. But as mentioned earlier, advancements in driving technology and proper driver training programs allow practiced and disciplined chauffeurs to easily manage this weight that is high and on the rear.

The configuration of the rear-mounted aerial offers the department a lot more options for compartments, ladder storage, equipment mounting, and additional department-required tools for firefighters to complete their assigned tasks on all types of incidents. The chance to be able to have at least two full-height, full-depth and through compartments is an advantage for the rear-mount aerial, allowing the department to store long and bulky items in these compartments and protect them from the weather.

Even though both types of aerials can have ground ladders stacked on the sides of the apparatus, the rear-mounted aerial allows the department to side mount a number of ladders and still have ample compartment room for equipment storage, unlike the midship aerial devices. Side-mounted ladders on midship aerials will greatly reduce their already limited compartment space.

On the rear-mount, there still is a swing-out driving problem but not nearly as dramatic as the midship aerial. Another one of the driving items to address is positioning the turntable. This all-important chauffeur task is one of the critical tasks that must be achieved to ensure proper aerial positioning and deployment. With the midship device, it is right behind the cab and easy to spot. The rear mount is a little tougher to see, being high on the torque box and having to look in the rear-view mirror to position. It will require a lot of practice, practice, and more practice to know where the turntable is in relation to the building you are getting ready to ladder.

The Ladders

One of the last things to discuss on this topic is the ladders themselves. With a midship-mounted apparatus, the available space to store the ladder itself is a much smaller space. This means that the ladder’s sections are shorter and there are more of them. A midship may have five ladder sections as opposed to the three or four of the rear-mounted aerial, which can use the space over the top of the cab to make the ladder sections longer.

Your choice in purchasing either device should be based, as always, on your response area and the needs of your community. Having discussions with your manufacturer about your requirements and special problems in your community will enhance its ability to help offer the correct device and options to properly serve your area.

Once that new aerial arrives, midship-mount or rear-mount, that is just the beginning. Drivers will need to become very familiar with the apparatus and all the intricacies associated with proper positioning. This will include spotting the device and jacks, achieving optimum scrub surface, tip placement on the building, and flowing maximum water. And, let’s not forget the all-important driving component, which will make the driver proficient while navigating streets, dealing with swing out, and reducing any damage to the apparatus or civilian vehicles. Constant driver training and refreshers on this apparatus will greatly reduce this damage and keep the truck available for the citizens instead of in a shop.

http://www.fireapparatusmagazine.com/articles/print/volume-23/issue-2/departments/fa-viewpoints/rear-mount-vs-midmount-aerial-ladders.html

I would like to hear about advantages you believe one or the other device has. Contact me at rriley@traditionstraining.com or on Twitter @TTCombatReady.

RICKY RILEY is the fire apparatus manager for the Prince George’s County (MD) Fire/EMS Department. He previously served as the operations chief for Clearwater (FL) Fire and Rescue and as a firefighter for Fairfax County (VA) Fire & Rescue. He also currently serves as the rescue-engine captain at the Kentland (MD) Volunteer Fire Department. He is a member of the editorial advisory board of Fire Apparatus & Emergency Equipment.

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