Underwater trench digger with pulsating pressure jets - has hydraulically operated water supply valve

摘要

The valve head is supported in a bracket co-axially with the nozzle. The valve body houses a spring which normally keeps the valve open. The upper end of the valve body is linked by a bell crank lever to the piston rod of a hydraulic ram mounted on a pivot. By supplying fluid at pressure to the ram the valve can be opened or closed, thus controlling the volumetric flow and velocity of the jet to suit varying conditions of excavation. Rapid motion of the ram gives a pulsating flow when required, by difficult excavating conditions.