Valve Hydraulic Excavator

hydraulic
(hydraulically) in a hydraulic manner; "the block is then tested hydraulically to its full design test pressure on each stream separately"
Denoting, relating to, or operated by a liquid moving in a confined space under pressure
Of or relating to the science of hydraulics
of or relating to the study of hydraulics; "hydraulic engineer"
(of cement) Hardening under water
moved or operated or effected by liquid (water or oil); "hydraulic erosion"; "hydraulic brakes"

excavator
A large machine for removing soil from the ground, esp. on a building site
A person who removes earth carefully and systematically from an archaeological site in order to find buried remains
power shovel: a machine for excavating
a workman who excavates for foundations of buildings or for quarrying
Excavators are heavy construction equipment consisting of a boom, bucket and cab on a rotating platform (known as the "house"). The house sits atop an undercarriage with tracks or wheels.

valve
A device for controlling the passage of fluid through a pipe or duct, esp. an automatic device allowing movement in one direction only
A cylindrical mechanism in a brass instrument that, when depressed or turned, admits air into different sections of tubing and so extends the range of available notes
A membranous fold in a hollow organ or tubular structure, such as a blood vessel or the digestive tract, that maintains the flow of the contents in one direction by closing in response to any pressure from reverse flow
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
control consisting of a mechanical device for controlling the flow of a fluid
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it