Overview - ISO 10521-2:2006 (Road load - Reproduction on chassis dynamometer)
ISO 10521-2:2006 specifies procedures for reproducing a vehicle’s road load on a chassis dynamometer so that subsequent tests (for example, fuel consumption or exhaust-emission measurements) accurately reflect on‑road resistance. It describes how to set the dynamometer’s power‑absorption characteristics based on road‑load data obtained by methods in ISO 10521‑1 (coastdown, torquemeter, wind‑tunnel/chassis‑dynamometer). The standard applies to motor vehicles (per ISO 3833) up to 3 500 kg and to chassis dynamometers able to set road load at a minimum of three speed points.
Key topics and technical requirements
- Road‑load reproduction methods
- Coastdown method reproduction (coefficients A, B, C or polygonal load points).
- Torquemeter‑based reproduction (conversion of torque coefficients using dynamic tyre radius).
- Wind‑tunnel & chassis‑dynamometer combination (refer to ISO 10521‑1 for measurement).
- Dynamometer types covered
- Focus on coefficient‑control (polynomial) and polygonal‑control dynamometers.
- Hydraulic absorber dynamometers are excluded for precise road‑load simulation.
- Setting and verification
- Initial coefficient-setting recommendations and empirical alternatives for initial loads.
- Verification via coastdown runs on the dynamometer and iterative adjustment if errors exceed criteria.
- Error acceptance bands for simulated vs. target road load: ≤3% for V ≥ 50 km/h, ≤5% for 20–50 km/h, ≤10% for V ≤ 20 km/h.
- Laboratory and measurement accuracy
- Roller condition: clean, dry, slip‑free.
- Laboratory temperature standard range: 293 K to 303 K.
- Required measurement accuracies (examples): roller speed ±0.5 km/h or ±1%; force accuracy categories defined (±6 N or ±10 N / 0.1% FS).
- Preparation and preconditioning
- Inertia/mass setting, tyre‑pressure adjustment (±5 kPa), vehicle positioning and preconditioning (recommendation: ~30 min at reference speed).
Applications - who uses ISO 10521-2:2006
- Vehicle test laboratories performing fuel consumption and emission certification on chassis dynamometers.
- OEM test engineers validating on‑road behavior in laboratory conditions.
- Regulatory agencies and conformity-of-production bodies that adopt dynamometer procedures for vehicle certification.
- Equipment manufacturers and calibration technicians implementing coefficient or polygonal control in dynamometer systems.
Related standards
- ISO 10521-1:2006 - Determination of road load under reference atmospheric conditions (measurement methods referenced throughout).
- ISO 3833:1977 - Vehicle type definitions and terms used in applicability.
ISO 10521-2:2006 is essential for consistent, reproducible reproduction of road load on chassis dynamometers - ensuring laboratory fuel‑consumption and emission results closely mirror real-world resistance for vehicles up to 3 500 kg.
