What is Hydraulic Excavator

Once upon a time the steam shovel held away in construction yards; a coal-fired boiler produced hot, expanding steam whose force ran a lifting winch and bucket. Today you're likely to find an excavator with the diesel engine that powers a mechanical system based on a liquid power.
The engine runs hydraulic pumps that draw oil from a tank and force it around interlocking gears, pressurizing it.
This oil is pushed through a set of valves controlled by the driver-operator and onto tubing that leads to pistons on the arm and basket as well as to hydraulic motors that use the force of pressurized oil to turn the excavator's caterpillar treads and spin it around on its base.
It's all based on Pascal's law; pressure applied to the oil at the pump is transmitted undiminished over considerable distance through narrow tubes to perform a variety of quick, powerful mechanical tasks.