Overview
ISO 5687:2018 - Equipment for harvesting - Combine harvesters - Determination and designation of grain tank capacity and unloading device performance - specifies a preferred method for measuring and designating the grain tank capacity and unloading performance of combine harvesters. The standard defines test conditions, sampling requirements, measurement procedures and calculation methods so manufacturers, test laboratories and purchasers can report consistent, comparable capacity and unloading-rate figures.
Key topics and technical requirements
- Test conditions
- Combine harvester must be stationary, horizontal and running at rated speeds; feed table and threshing engaged.
- Machine must be in good working order with a minimum run-in of three fill/empty cycles.
- Test grain properties
- Wheat moisture (wet basis) between 10 % and 17 % (ISO 712).
- Impurity level ≤ 3 % (ISO 7970).
- Mass per litre between 0.73 kg/l and 0.81 kg/l (ISO 7971-2). A sample must be taken and recorded.
- Measurement procedures
- Recommended: continuous weight vs time recording at ≥ 5 Hz while unloading; analyze weight-time data to compute rates and times.
- Alternative: two-collection-area method with timed diversion and mass measurements.
- Calculations and definitions
- Maximum unloading rate: based on the 30 s period with the highest discharge (litres/s).
- Unloading time: time from activation to the point the 1 s moving-average rate falls to 2.0 % of the maximum.
- Grain tank capacity: mass collected during unloading time divided by measured mass per litre (reported in litres).
- Average unloading rate: capacity divided by unloading time.
- Designation: capacity rounded upwards to the nearest 100 L.
- Documentation requirements
- Machine ID, header and unloading device model, test method used, capacity, average and maximum rates, moisture/impurity/mass-per-litre, unloading time, technician and test location.
Practical applications and users
ISO 5687:2018 is used by:
- Combine harvester manufacturers - to rate and publish grain tank capacity and discharge performance.
- Test laboratories and certification bodies - for reproducible performance verification.
- OEM engineers and R&D teams - for design validation and comparative benchmarking.
- Purchasing agents, large-scale farmers and fleet managers - to compare machines on unloading speed and effective tank capacity for operational planning.
- Regulators and standards committees - to harmonize labelling and performance claims.
This standard helps ensure consistent, comparable data for marketing, procurement and operational planning where grain tank capacity and unloading device performance are critical.
Related standards
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