Patent ID: 6189243
Filing Date: 2001-02-20
Classification: E02F

Abstract:
A method of dredging sand and gravels in a dredging apparatus including,a case being laid down into water in communication with the atmosphere;a suction pipe having a suction portion at a lower end thereof, said suction pipe being connected to said case;a dome-shaped cover being provided to the lower end of said suction pipe so as to cover over the suction portion;a spout pipe whose one end is opened in said dome-shaped cover;a spout pump for spouting water, with high pressure, from said spout pipe toward a bottom of water;a drain pump for draining water in said case; anda container being removably disposed at an intermediate portion, of said suction pipe, said method comprising the steps of:spouting water, with high pressure, from said spout pipe toward the bottom of the water by said spout pump;draining water in said case so as to form a space therein and to form a level difference between a water level in said case and an external water level; andsucking the sand and gravels from said suction pipe into said container by a water current caused by the level difference.