How it Works

Nearly all truck-based commercial vehicles utilize a conventional leaf spring rear suspension system. For the auto maker, these are simple and inexpensive systems that deliver the desired load-carrying capacity. SANLUIS Rassini engineers and manufactures nearly 100 percent of the leaf springs used under new light trucks in North America, so we understand the qualities of this design. We also knew we could develop a better system that delivers more value to the commercial vehicle owner and operator.

Hybrid System

We developed a hybrid system that uses the best attributes of our leaf springs for axle location and control and air springs for adjustable ride-height and load-carrying capacity. Using the latest computer-aided engineering (CAE) technologies and our 70-plus years of experience in suspension design, we created an all-new suspension system that improves vehicle handling both loaded and unloaded, improves braking performance and delivers a much improved ride quality.

Better Axle Control

Our R4Tech Suspension system replaces the heavy, thick leaf spring pack with springs having far fewer leafs. We provide a new front spring eye bracket that mounts both the new main leaf spring and a new lower link. A patented "J" spring is incorporated into this lower link which controls axle windup, reducing wheel hop on acceleration and axle shudder during braking.

Adjustable Spring Rate

Air springs offer variable spring rate, adjusted with air pressure. When your vehicle is unloaded, the system automatically decreases the air pressure, providing a lower spring rate and a smoother ride. When cargo is added to the vehicle, the air pressure is increased, providing the needed cargo-carrying capacity and maintaining a level ride height.

Load-adaptive Shocks

The R4Tech is a complete suspension system, including load-adaptive shocks. These shock absorbers have custom valving that is automatically adjusted with the air springs. They provide more control when there are heavier loads in the vehicle and a softer ride when the vehicle is unloaded.

Self-leveling System

Our system includes height-control valves that monitor the ride height and adjust the suspension as necessary to accommodate added or removed cargo weight.