Lifting Bridge Suspension Design on Semi Trailers

What Makes It Different

Unlike general first-bridge or third-bridge lifting used on foreign trailers, this design lifts one and three bridges at the same time. Lifting two axles rather than one changes the economics of running light or part-loaded, because the fuel and tire saving roughly doubles.

The Suspension Arrangement

There are four sets of steel plate suspension and two sets of air bag suspension. The three axles share four leaf spring suspensions, and the air bags are mounted on the two steel plate suspensions of the second bridge. That arrangement is what lets the outer two axles be raised while the centre axle carries the load.

How the System Works

The complete system consists of an air storage cylinder, an air bag, a solenoid valve, two load sensors and two quick release valves. Inflating the air bag presses the leaf spring down, which lifts the outer two bridges. Discharging the air bag returns them to the ground. The load sensors are what make it automatic rather than manual.

The National Patent

The design obtained a national patent. What it delivers in service is an improved damping effect for the vehicle, reduced fuel consumption and reduced tire wear, all of which come from not dragging unloaded axles along the road.

When Axle Lifting Pays

Axle lifting earns most in operations with a high proportion of empty or part-loaded running: shuttle work with a loaded leg and an empty return, or seasonal operations where the trailer runs light for months. On a permanently loaded trailer it adds complexity for little gain.

What to Consider Before Specifying It

Lifting systems add pneumatic components, sensors and valves. In markets with good service support that is a reasonable trade for the fuel and tire saving. On remote sites with no diagnostic capability, weigh it carefully against the simplicity of fixed mechanical suspension.