2008年3月28日 星期五

drop gate

drop gate 落砂(铸疵) 铸造学词典-D

The approach of vessels could be detected by the rise in the depth of the water, due to the release of the water from the lock further up the canal. The boats were guided along a wharf built along the canal at the lock to keep them from hitting the banks. When the boat was positioned, the drop gate would be lowered and the wickets opened slightly, bringing the vessel into the lock.


圖集

http://images.google.com/images?hl=en&q=DROP+GATE&btnG=Search+Images&gbv=2



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