Suspension gives PAWS for thought
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• A new suspension system is said to reduce road damage and offer the ride quality of active suspension at much lower cost.
PAWS (Pro-Active World Suspension), developed in a £ 500,000 IVIIRA/DTi project, can be applied to steering, drive or trailer axles—a PAWS-equipped Ford Cargo drive axle showed less body movement and wheel hop on cobblestones than steel springing.
MIRA claims that PAWS outperforms air systems in all laden situations and that dynamic tyre force—blamed for road damage—is reduced by 20%. Ride quality is improved with no effect on handling.
A trailing-arm hydraulic ram is connected via throttle valves to two accumulators containing gas springs. The -first unit filters out wheel-related vibration, while the second deals with body bounce.
However manufacturers have suggested that PAWS would increase cost and weight while reducing reliability: MIRA calculates a production cost of £260/axle over air, excluding selflevelling and height adjustment.
Operators are unlikely to pay for improved ride quality alone, but MIRA foresees a range of applications in cars, coaches, military vehicles and trains.