Overview
ISO 17900:2002 provides a standardized method to determine the payload, vertical static drawbar load and axle loads of agricultural balanced and semi‑mounted trailers. The standard defines required measurements, weighing procedures and calculation steps so that trailer empty mass and structural dimensions can be used to calculate safe working loads and maximum mass. Keywords: ISO 17900, agricultural trailers, payload determination, axle load, vertical static load.
Key topics and requirements
- Scope and definitions: Clear definitions for semi‑mounted trailer (rigid drawbar that can transmit vertical forces) and balanced trailer (drawbar allows vertical movement so forces are not transferred to the towing vehicle). Other defined terms include axle load, vertical static load, empty mass, maximum mass, payload and dimensional parameters (wheel space, load platform length, supporting distance, drawbar length, auxiliary height).
- Weighing methods: Empty mass and empty axle/support loads shall be determined using a suitably sized weighbridge and/or load pad scales.
- Measurement tolerances: The trailer load platform must be horizontal within ±2°; all weightings and dimensional measurements shall be accurate to ±5%.
- Measured dimensions: Required dimensions include wheel spacing (front/rear or combined), load platform length, supporting distance and drawbar length (and an auxiliary height for balanced trailers).
- Calculation rules: The standard prescribes formulas to compute:
- empty axle and support loads from measured wheel loads;
- vertical static load for empty and laden semi‑mounted trailers;
- axle loads for semi‑mounted and balanced trailers when laden to maximum mass;
- payload as the difference between maximum mass and empty mass.
- Manufacturer limits: The standard notes that maximum permissible axle load and vertical static load are specified by the trailer manufacturer.
Applications and who uses ISO 17900
- Trailer manufacturers - to verify design load ratings and publish compliant payload and axle load specifications.
- Test laboratories and certification bodies - to perform repeatable, standardized load tests and certification against design limits.
- Agricultural machinery designers and engineers - to size drawbars, axles and suspension and to ensure compatibility with towing tractors.
- Fleet operators, safety inspectors and regulators - to check that trailers are loaded within safe limits and comply with declared capacities.
Related standards
- ISO 12140 (Agricultural machinery - Drawbar jacks) is referenced for drawbar support considerations.
ISO 17900:2002 is essential for safe, consistent payload and axle‑load determination of semi‑mounted and balanced agricultural trailers, supporting compliance, design validation and operational safety.
Open preview (PDF)Agricultural trailers — Balanced and semi-mounted trailers — Determination of payload, vertical static load and axle load
