By Christian P. Koop
The steering systems found in most heavy-duty fire apparatus and rescue trucks or emergency response vehicles (ERVs) have not changed much in the past 40 years.
Sure, most are heavy-duty, power-assisted steering systems that have been durable and reliable over the years, but when it comes to keeping pace with other technological innovations that have added improved efficiency and safety to the overall vehicle, it has not happened. This includes the ones rolling off the assembly line right now as this article is written. This is referring to the commonly used hydraulically assisted steering boxes or gear boxes found on most medium- and heavy-duty trucks. Most of these are the recirculating gear or ball-nut type with hydraulic assist and generally installed directly onto the driver’s side frame rail. There are some with electronically variable steering that basically change how much effort the driver has to use to turn the wheel, and it changes in relation to road speed by increasing or decreasing hydraulic assist pressures.
There are several variations of these. However, most importantly, they are all fixed ratios, meaning the speed at which the wheels turn in relation to the driver turning the steering wheel is the same throughout the complete range of steering. This is sometimes referred to as lock to lock or stop to stop. Important to note also is that steering speed does not change in relation to vehicle speed either. The systems have reduction ratios so drivers can have a mechanical advantage, and engineers design the systems to find the best balance between reduction and steering speed for each application. But, the main point here is it is still a fixed-ratio system.
In one of my past articles, I wrote about how commercial trucks, in general, seem to lag behind the automobile industry in technological improvements. The same goes for ERVs. Well, Ford Motor Company just came out with a new steering system it calls adaptive steering, which is a great innovation in steering technology that will make steering easier; more efficient; and, when it comes right down to it, especially for ERVs, a safer steering system for all drivers and operators. Some manufacturers have made changes to the front suspension by offering independent suspension over the traditional I-beam in search of better performance and ride quality, but when it comes to the steering ratio, there have been virtually no changes, and most are all still fixed. This can be a detriment to the driver because a fixed ratio is still a tradeoff between providing safe, comfortable steering response at higher vehicle speeds and ease of steering and maneuverability at slow speeds. This also includes fire apparatus and ERVs in general. I have also written about the difficulty and danger involved in driving ERVs, particularly while on an emergency call, and Ford’s new system will definitely help in this vital area.
It may be several years before the ERV original equipment manufacturers (OEMs) develop and produce adaptive steering for the medium- and heavy-duty market. If some of these improvements could be introduced to the ERV market sooner than seen in the past, it would mean a big leap in technology for this industry. Improved safety is generally the main goal of major innovations that have come out over the past 25 or so years from the auto and truck manufacturers. The innovations that have made major improvements in safety help the driver maintain directional stability or from losing control of the vehicle. Keep in mind that the main goal behind these innovations is to reduce accidents and save lives. These major leaps in technological improvements are now common on most vehicles and include antilock brake systems (ABS), automatic traction control (ATC), rollover stability control (RSC), and others. The effects these safety improving innovations have had over the years are comparable to the advancements in emission-reducing devices such as catalytic converters and diesel particulate filtration (DPF) that have reduced harmful tailpipe emissions in the automotive and heavy truck industry. By and large, these safety improvements over the years have contributed immensely to reducing automobile and truck accidents in the United States and around the world. Ford’s adaptive steering is a major one that should also fall in the category of innovations that improve vehicular safety. Think about all the possible benefits to fire departments, and citizens in general, if ERV accidents could be reduced-even if only by a small percentage. Improvements in departmental response times, equipment downtime, and budgetary savings are possible. And, most importantly, even lives could be saved.
About Adaptive Steering
Adaptive steering essentially changes steering ratios based on vehicle speed and makes steering effort easier and smoother for the driver. It will also be more comfortable at higher speeds and will serve to cut down on driver fatigue. All these factors result in greater safety for any vehicle equipped with this system. Ford debuted the system on its 2016 Edge Sport and will be offering this new steering technology on all its new F Series Super Duty trucks and the Edge sport utility vehicle. Ford also has a tow/haul option on its Super Duty series that further improves how the trailer reacts to steering input. Ford currently holds eight patents for adaptive steering and has applied for 11 more.
It would be a great option if the fire apparatus and heavy rescue truck OEMs would offer adaptive steering in their vehicle lines. It does not take up much real estate because it fits right inside the steering column and basically just inside the steering wheel. It can work with either a traditional hydraulic system that is still found in most ERVs or even the more modern totally electric systems. It fits very comfortably in Ford’s F Series Super Duty steering column, so there should be no reason for the ERV OEMs not to offer it. It is totally electrically controlled through an electronic control unit that receives several inputs, such as road speed and driver input. The drive system sits just inside the steering wheel and consists of a drive gear unit and electric motor assembly. Adaptive steering has several benefits, one of which helps reduce driver fatigue by reducing the steering wheel rotations by up to one full revolution at slow speeds or during parking maneuvers when the driver is more likely to turn the wheel from steering stop to steering stop.
An article recently appeared in Fire Engineering about an ERV accident that occurred in Ventura County, California. A 2,000-gallon tanker truck was responding on an emergency call around 6:00 a.m. when it hit the curb of a traffic circle (roundabout) and flipped onto its side. The passenger, a fire engineer, was killed, and the driver suffered minor injuries. ERVs equipped with adaptive steering may help or go a long way toward preventing and reducing these types of accidents because it can increase or decrease steering speed and effort depending on vehicle speed.
It may take a few years before the medium- and heavy-duty ERV OEMs can develop and produce adaptive steering for the market. Because the system is not really intrusive, wouldn’t it be great if the OEMs could also offer retrofit kits for older units?
CHRISTIAN P. KOOP retired as the fleet manager for the Miami-Dade (FL) Fire Department after 35 years with Miami-Dade County and four years in the military. He has been involved in the repair and maintenance of autos, military track and wheeled vehicles, heavy equipment, and emergency response vehicles for the past 40 years. He is a member of the Fire Apparatus & Emergency Equipment Editorial Advisory Board. He has an associate degree from Central Texas College and a bachelor’s degree in public administration from Barry University and has taken course work in basic and digital electronics. He is an ASE-certified master auto/medium/heavy truck technician and master EVT apparatus and ambulance technician. He is a member of the board of directors of EVTCC and FAEVT and a technical committee member for NFPA 1071, Standard for the Emergency Vehicle Technician Professional Qualifications.