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.
New Technology
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), automati