Hydraulically controlled and driven bucket wheel dredge

A hydraulically controlled and driven dredge governed directly by working pressure which includes:

• a bucket wheel, track laying means, a lower structure supported by said track laying means, an upper structure supported by said lower structure and pivotable about a vertical axis relative to said lower structure, a boom pivotable in a vertical plane and supported by said upper structure and supporting said bucket wheel, first hydraulic motor means drivingly connected to said bucket wheel for driving the same, first pump means for delivering actuating fluid to said first hydraulic motor means, actuating fluid conveying first conduit means leading from said first pump means to said first hydraulic motor means, power control means responsive to changes in the digging resistance encountered by said bucket wheel and operatively connected to said first pump means for varying the delivery thereof in conformity with said varying digging resistance of said bucket wheel, second hydraulic motor means operatively connected to said upper structure for pivoting the same about its vertical axis, second pump means arranged in a closed circuit with said second hydraulic motor means for delivering actuating fluid thereto, power output limiting valve means, second conduit means branching off from said first conduit means and connected to said power output limiting valve means, control circuit means including an adjusting unit and manually adjustable control means hydraulically connected to said adjusting unit by said control circuit means, said control circuit means hydraulically communicating with said power output limiting valve means, third hydraulic motor means drivingly connected to said track laying means for driving the same, third hydraulic pump means, third conduit means connecting said third hydraulic pump means to said third hydraulic motor means, additional valve means interposed in said third conduit means, and fourth conduit means connected to said additional valve means and leading to said first hydraulic motor means, said additional valve means being operable selectively to interrupt the supply of actuating fluid from said third pump means to said third hydraulic motor means when said track laying means is not to be operated and to convey the delivery from said third pump means to said first hydraulic motor means through said fourth conduit means.