Italy and Europe have always stood out as world-class excellences in mechanics, design and engines, but also in the refined engineering of structural and elastic systems. Among these, the De Dion Bridge, invented at the end of the nineteenth century by the French marquis of the same name and subsequently perfected by Italian engineers: a solution that combines stability and comfort, also successfully adopted in numerous military configurations.
Even in rubber-wheeled military vehicles, suspension is not just a technical detail, but a vital component for operational survival.
The systems that guarantee elasticity between the chassis and the wheels are mainly based on leaf springs, coil springs and telescopic shock absorbers, often combined with fluids such as oil, gas or compressed air. Each system responds to different needs, such as robustness and simplicity for the most hostile theaters, precision and adaptability for high-performance vehicles. The choice of suspension is therefore a technical question as well as strategic and operational.
Il De Dion Bridge (photo below) has been used in light or self-propelled tractors to offer mechanical strength and construction simplicity, separating the unsprung load.
Some Italian and German vehicles between the two wars exploited this system to improve wheel traction in semi-arid conditions.off-road.
In the civilian sector, suspensions improve comfort and road holding, while in the military sector the objectives change: mechanical resistance, adaptability on any type of terrain, ease of maintenance and high load capacity are fundamental requirements and StanAG.
The vehicle must not only transport personnel or materials, it must do so through deserts, mud, debris and explosions, without giving way. Even tanks have suspensions (spring or telescopic) on the return rollers. Therefore, the "elastic" task of the suspensions is not only to ensure road holding and comfort, but also to manage the moving masses; for this reason tactical vehicles have frames with greater thicknesses. A frame that bends under strong pressure knocks out a tactician and compromises a mission. The initial choice is fundamental.
Strategic comparison
Rigid axle - It is the undisputed king of military vehicles: very robust, easy to repair, capable of withstanding extreme loads and stresses. Used on jeeps, tactical trucks and heavy armored vehicles, its architecture, combined with leaf springs (leaf springs) or shock absorbers, guarantees ideal performance on rough terrain. In addition, the hubs may have links to raise the ground clearance (the ground clearance).
The crossbows - Despite their antiquity (horse carriages and wagons), leaf springs are still very common in military vehicles. Composed of overlapping layers of steel (leaves or blades) held together by a central rib, they offer progressive elasticity and extraordinary strength, often combined with shock absorbers to improve their effectiveness and comfort. Ideal for exceptional loads and in environments where maintenance is limited and reliability must be absolute. They are simple, economical and almost indestructible.
Independent suspension - Used in light armored vehicles and modern MRAPs, they allow each wheel to react autonomously to obstacles while keeping the chassis - theoretically - almost flat; thus improving mobility and protection of the occupants. A system also widely used in the civil automotive sector to reduce stress and improve road holding. Often equipped with coil springs and shock absorbers, they are, due to their complexity, a bit delicate.
Double wishbone (double triangle or wishbone) - Advanced system used in special vehicles, offering precision and great excursion. It is used in high-performance armored vehicles, such as those of Oshkosh Defense intended for special operations. A compromise between sophistication and robustness, it frequently uses springs or hydropneumatic springs, with shock absorbers sometimes integrated with sophisticated systems. However, the ideal suspension must keep the wheel perpendicular to the ground during rolling, avoiding unwanted variations in camber and convergence, which would alter the trajectory. It must ensure vertical movements by compensating for the effect of rolling (lateral oscillation) through the recovery of the camber - inclination of the wheel with respect to the vertical -, without introducing elastic deformations that compromise the geometry and stability of the vehicle.
Air and hydropneumatic suspensions - Used in buses and for the comfort of luxury sedans, they are also growing in the military sector – e.g. Iveco SuperAV – especially in logistics vehicles. They allow the adjustment of the height from the ground and the rigidity, optimizing the trim in any load condition, offering an appreciable road holding. The protection of the elastic system, often integrated with shock absorbers, must be evaluated on a case-by-case basis. On reliability, sources such as Oshkosh, Rheinmetall and BAE Systems, prefer for real tactical vehicles (MRAP, 4x4 or 6x6 wheeled armored vehicles) independent suspensions with coil springs and telescopic shock absorbers, more robust in a war context. The problems encountered include: splinters and perforating shots, pressure losses in the event of damage to the system and difficulty in repairing in the field. Problems similar to those encountered in civil road transport.
Mixed and hybrid system - Some new-generation vehicles are exploring the adoption of mixed and hybrid systems. They combine semi-active, electronic and hydraulic suspensions to further improve dynamics, safety and adaptability to variable terrain. An example is the ATREX system from RENK, which integrates advanced suspensions such as the InArm system.
ATREX is not a suspension, but its design interacts closely with the vehicle's suspension system. These are integrated solutions that combine advanced transmissions with suspension and damping to optimize vehicle performance. Designed to improve the mobility and stability of combat vehicles, it offers a mixed solution between the benefits of traditional systems and technological innovation.
Tradition and innovation - The Italian industry has been able to integrate classic robustness with modern solutions; an example is the Lynx VTLM 2 NEC, which combines independent suspension with armoured solutions, thus ensuring optimal protection, agility and stability, even on difficult terrain. In other cases, such as in the ASTRA/Iveco ACTL logistics vehicles, the rigid axle and leaf springs are preferred, a condition that improves the overall appearance of logistics and exceptional operations. This type of suspension has almost never created problems in the most extreme uses.
Every terrain has its own spring
In modern warfare, where speed is vital and mines are a constant threat, the choice of suspension is far from trivial. Damage to the suspension can cripple the vehicle.
It is not just a question of technique, but of strategy. Leaf springs and springs, axles and arms, are solutions that require compromises, since military mobility (and it is good that it is so) is anchored to a simple principle: resist, always.
Photo: US Air National Guard / web / US Army / Renk
