| 摘要 |
The invention relates to a bridge scraper for raking material from a storage heap onto a belt conveyor by means of a scraper chain mounted on a bridge which also carries a carriage which feeds material from the heap to the scraper chain. The speed of the conveyor and that of the bridge, the scraper chain and the carriage is controlled by means of a bolt weigher at the outlet end of the belt conveyor which controls the speed of the belt and consequently that of the other elements of the bridge scraper so as to discharge a constant amount of material per unit time. A further measuring device is mounted on the bridge for travel with it so as to measure continuously the degree of filling of the belt at a point immediately after that at which it receives material from the scraper chain and the measuring device controls the relationship between the speed of the bridge and that of the scraper chain, carriage and belt conveyor to increase the relative travelling speed of the bridge when the belt filling rate drops below a predetermined value and to decrease it when the belt filling rate exceeds that predetermined value.
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