1. The “big” AGRETO drive-over-scale is controlled by PC software. This software doesn’t just manage data, but also monitors and assures the quality of weighings. All the usual vehicle scale accessories, like outdoor displays, remote control, traffic light signalling, image processing and protocol printers and log printers can be delivered.
2. The platform has a length of 100 cm (in the driving direction). This is the only way one can weigh large tractor rear tyres.
3. The platform is equipped with a light barrier system. This enables the recognition of driving direction, driving speed, tyre size, wheelbase and the overlapping of axles on the platform. These functions turn an axle load scale into a reliable vehicle scale.
You simply drive your vehicle over the scale. The weighing procedure is started automatically as soon as the first axle applies a load to the platform. 60 weighing points per second are made while the axle crosses the platform. These enable the software to calculate axle weight. When the axle leaves the platform, the pre-set waiting time starts (for instance, 10 seconds). A new weighing procedure starts if within that time another axle crosses the platform. When this doesn’t happen, the weighing procedure ends, and total vehicle weight is calculated and logged.
During a static weighing every axle stands still on the platform. The software contains a separate mode for this. When applied, the large display signals whether an axle is situated in the middle of the platform, at what point axle load is stable and whether motion can be resumed. After the last axle and subsequent waiting period the weighing procedure ends, and total vehicle weight is calculated and logged.
With vehicles with multiple axles and a narrow wheelbase it could occur that the first axle is still on the platform when the second axle enters it. This situation isn’t a problem for the AGRETO drive-over-scale. The light barrier system locates the exact position of the axles and determines whether an axle can be weighed or not. As soon as a second axle enters the platform, weighing of the first axle is stopped.
For weighing trucks a smaller platform would be sufficient. For agricultural vehicles however, the tractor must be included in the weighing because of high vertical loads. This makes a 1 m long platform a prerequisite. Large low pressure tyres can have a wheel contact surface of up to 90 cm under load. On top of that, a larger platform enables the AGRETO drive-over-scale light barrier system to optimize the quality of weighings. All axles are weighed for as long as possible, depending on the contact area.
A calibrated weighing for legal transactions can only be produced by a scale on which a vehicle can stand in its entirety. Axle by axle weighing cannot produce a calibrated total vehicle weight. The AGRETO drive-over-scale is used as a checkweigher for internal use. One advantage is that there aren’t any calibration costs.
The built-in load cells have an accuracy of 0.02% and can be calibrated. Axle weight is calculated in 1 kg increments, total vehicle weight in 10 kg increments. The scale’s accuracy is essentially higher than that of a weighbridge. The decisive factor, however, is the roadway in front of and behind the scale. In practice, proper installation and use will guarantee only minimal deviations from a calibrated weighbridge.
The weighing platform must be built into a foundation that is constructed on site. You receive plans and detailed installation instructions for building the foundation and installing the platform. A prefabricated foundation isn’t an option due to high transportation costs.
The scale should ideally be positioned in such a way that vehicles that need to be weighed, pass there anyway when leaving or entering the farm. Of course, the terrain has to be suited for the construction of a drive-over-scale. The possibility of regular traffic driving over the scale should be avoided. Although this won’t damage the scale, it will get dirty faster and every crossing is registered if the software is active.
When choosing a location for your scale, make sure that the area for approaching and exiting the scale is as even as possible, for the entire length of the vehicles that need to be weighed (30 to 32 m in total for semi-trailer trucks). Ideally this roadway is level in all directions. A slight slope to the side or upwards in the driving direction is acceptable, when this slope is exactly the same everywhere on approach, scale and exit. For weighing multiple axles we advise the construction of a concrete slab at least 3 m before and after the weighing platform. The approach and exit are essential parts of the scale and must be constructed with care.