Suspension seating in occupational vehicles and wheeled equipment has become a far more sophisticated concept than in the days of stiffly sprang stamped metal seats on red iron farm tractors. Over the past 40 years, the debilitating effects of shock and vibration on spines, necks and other body parts of people who make their living operating such equipment over rough terrains have become well-documented. Several approaches to occupational suspension seating have thus evolved, including mechanical and air suspension seating.
Suspension Occupational Vehicular Seating
Suspension seating is not a luxury. It is designed to provide protection from shock and vibration that allows drivers to operate their equipment--farm equipment, construction equipment and freight transportation vehicles--over full workdays and weeks without negative effects to their health. Because no set formula described the nature of the challenges drivers faced from day to day, including amplitude and frequency of the shock and vibration, developments tended to be limited to satisfying new regulations. This is not often the best way to motivate improvements in any technology.
Modern Suspension Seating
By 2010, the intention of suspension seating in occupational vehicles travelling over rough terrain was to provide safety and comfort that allows operators to perform their job continuously without ill effects. Unlike the road car, it would be technically impractical and prohibitively expensive for an entire bulldozer moving boulders and clearing trees to ride smoothly. It is totally possible, though, to provide the operator with a smooth, vibration-free environment by putting the tuned suspension specifically into the seating environment, not to mention the machine-control interfaces. Out of this have arisen both mechanical and air or pneumatic suspension seating, both of which embody certain characteristics.
Mechanical Suspension Seating
Mechanical suspension seating closely mimics the dynamics of the finely tuned suspensions of smooth-riding passenger cars with a complement of articulated joints and levers integrated with coil springs as well as energy-damping shock absorbers. Like all modern suspensions, they are designed around isolating both shocks and vibrations with varying amplitudes and frequencies from the equipment operator. They can be adjusted for the size and weight of the operator along with range of motion to some extent.
Air Suspension Seating
Air suspension seating also provides up-and-down and lateral damping of motion and vibration. The springing is accomplished somewhat differently, though, which provides several further benefits. First, the range of operator sizes and weights is much greater because a pneumatic system is so much more easily adjusted merely by varying air pressure. Secondly, unlike mechanical springs, which vary in spring rate the more they are displaced, pressure-based springs can be designed to maintain a constant force over their full travel.
Comparing Mechanical and Air Suspension Seating
Mechanical suspensions are simpler of necessity. They are aimed at being satisfactory for most applications with average-sized people and most terrain conditions. Air suspension systems, on the other hand, are almost infinitely and continuously adjustable for extremes of operator size and weight, terrain and shock absorber tuning. This lends them to adaptive systems that continuously sense these parameters and instantaneously self-tune the seat to the operator, as well as the variable terrain conditions. Many people consider the safety and comfort benefits to be well worth the extra cost and gladly select the option.