The excavator arm

Hydraulic excavators work by allowing the operator to use levers to control the movement of the hydraulic system to push and move the cylinders that control the boom and bucket of an excavator.

It is composed of three hydraulic pistons that operate in tandem with steel piston arms. The two main sections and bucket loader are connected by means of a hinge. The extension of the first piston widens the section at the same time as increases in girth, providing further reach for the operator.

An excavator is a large construction machine made for digging into the ground with its bucket to extract earth or other material to create trenches, holes and foundations. It usually runs off diesel fuel and, depending on the size of the equipment, can be used on a medium to large job-sites.

The arm movement on excavators is 100% hydraulically controlled.  The excavator’s arm forms part of the lower frame chassis.  The arm consists of two sections – the boom (the section from the excavator to the arm) and the arm (from the boom to the bucket) which are joined by a hinge.  Both arm and bucket are controlled by three separate hydraulic cylinders, which operate together to allow the arm to extend and retract.

Piston one is attached beneath the boom and when it is extended, the arm lifts up.

The second piston is attached to the top of the arm and this gives more reach by raising and lowering the arm.

The third piston controls the motion of the bucket to enable it to scoop and dig.

How does a excavator hydraulic system work?

Hydraulic systems use the pump to push hydraulic fluid through the system to create fluid power. The fluid passes through the valves and flows to the cylinder where the hydraulic energy converts back into mechanical energy. The valves help to direct the flow of the liquid and relieve pressure when needed.