Research & Development

N.V.H. Testing - low noise with "emission standard" accuracy - Froude Hofmann's range of extreme low noise N.V.H. Chassis Dynamometer systems have evolved and acquired techniques and capabilities previously only demanded in "high accuracy" emission test systems. Today's N.V.H. chassis dynamometer will typically be a 4x4 "independent roll" configuration providing maximum flexibility of tests in a S.A.C. test chamber. The latest generation developed by Froude Hofmann utilise a.c. machines, with high response inertia simulation capability and emission standard road simulation accuracy - enabling highly representative testing of the vehicle in simulated road conditions. Advanced acoustic engineering techniques and analysis models have produced a solution to the conflict of potential machine noise from high response ac systems by employing extensive noise containment and attenuation techniques. The unique roll design and construction, hydrodynamic bearings and optimised driveline design also ensure an extremely low noise capability (typically 45dBA at 100Km/hr). This configuration also provides many more benefits including, accurate and responsive roll speed synchronisation, phase lock (relative position control) of the rolls e.g. for "bump" testing, corner simulation, independent wheel control and a major practical benefit of complete free access under the vehicle drivetrain area (no centre shafts).