Weigh bridge

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A weigh bridge at a gravel pit. The weigh bridge is the two part platform over which trucks are driven. The upper works is auxiliary equipment for leveling the load in the truck and is not part of the scale. This scale uses electronic measuring equipment.

Electronic indicator for the bridge shown above. This allows input of the vehicle empty wieght and can compute and display the amount of material.

A moveable weigh bridge

A weigh bridge, also commonly known as a weighbridge or truck scale is a device for weighing loads carried by road or rail wagons. It is a very heavy duty weighing scale which can weigh the vehicle both empty and when loaded and thus calculate the load carried by the vehicle. In earlier versions the bridge is installed over a rectangular pit that contains levers that ultimately connect to a balance mechanism. The most complex portion of this type is the arrangement of levers underneath the weigh bridge since the response of the scale must be independent of the distribution of the load. Modern devices use multiple strain gauges that connect to electronic equipment to totalize the sensor inputs. In either type of semi-permanent scale the weight readings are typically recorded in a nearby hut or office.

For many uses (such as at police over the road truck weigh stations or temporary road intercepts) weigh bridges have been largely supplanted by simple and thin electronic weigh cells, over which a vehicle is slowly driven. A computer records the output of the cell and accumulates the total vehicle weight. By weighing the force of each axle it can be assured that the vehicle is within statutory limits, which typically will impose a total vehicle weight, a maximum weight within an axle span limit and an individual axle limit. The former two limits ensure the safety of bridges while the latter protects the road surface.

[edit] See also

Weigh lock, a portion of a canal used to weigh barges
Bridge, for an index to various bridge articles
Weighbridge, A section describing the uses and suppliers of Weighbridges in the UK