A typical excavator structure includes a power unit, working device, slewing mechanism, control mechanism, transmission mechanism, traveling mechanism, and auxiliary facilities.
The transmission mechanism transmits engine power to hydraulic motors, cylinders, and other actuators via a hydraulic pump, driving the working device to perform various tasks.
The traveling device, also known as the chassis, includes the track frame and the travel system. It mainly consists of the track frame, travel motor + reducer and its piping, drive wheels, guide wheels, track rollers, support rollers, tracks, and tensioning/buffering devices. Its function is to support the weight of the excavator and convert the power transmitted from the drive wheels into traction, enabling the machine to move.
The chassis assembly (i.e., the tracked traveling frame assembly) is a welded integral component with an X-shaped structure. Its main advantage is its high load-bearing capacity. The chassis assembly is welded from three parts: the left longitudinal beam (left track frame), the main frame (intermediate frame), and the right longitudinal beam (right track frame). The chassis assembly weighs 2 tons.
The central slewing joint is a hydraulic component connecting the slewing platform to the chassis hydraulic circuit. It ensures that the travel motor can still supply oil normally after the slewing platform rotates to any angle. The currently used slewing joint is a 5-way joint.
Working Device The working device is a major component of a hydraulic excavator. Currently, the SY series excavators are equipped with a backhoe working device, which is mainly used for excavating soil below the machine's stopping surface, but can also excavate soil below the maximum cutting height. Besides digging pits, trenches, and loading, it can also perform simple site leveling work. Excavation operations are suitable for excavating Class I to IV soil; Class V and above require a hydraulic hammer or blasting.
The backhoe working device consists of the boom, stick, bucket, rocker arm, connecting rod, and hydraulic pipelines including the boom cylinder, stick cylinder, and bucket cylinder.
Power Transmission Route Table
Travel Power Transmission Route: Diesel engine – Coupling – Hydraulic pump (mechanical energy converted to hydraulic energy) – Distribution valve – Central rotary joint – Travel motor (hydraulic energy converted to mechanical energy) – Gearbox – Drive wheel – Track chain – Achieve travel
Swing Motion Transmission Route: Diesel engine – Coupling – Hydraulic pump (mechanical energy converted to hydraulic energy) – Distribution valve – Swing motor (hydraulic energy converted to mechanical energy) – Gearbox – Swing bearing – Achieve swing
Boom Motion Transmission Route: Diesel engine – Coupling – Hydraulic pump (mechanical energy converted to hydraulic energy) – Distribution valve – Boom cylinder (hydraulic energy converted to mechanical energy) – Achieve boom movement
Hoist Motion Transmission Route: Diesel engine – Coupling – Hydraulic pump (mechanical energy converted to hydraulic energy) – Distribution valve – Hoist cylinder (hydraulic energy converted to mechanical energy) – Achieve stick movement
Bucket Motion Transmission Route: Diesel engine – Coupling – Hydraulic pump (mechanical energy converted to hydraulic energy) – Distribution valve – Bucket cylinder (hydraulic energy converted to mechanical energy) – Achieve bucket movement
Powertrain System Composition and Functions
Intake System: Grille → Hose → Air Filter → Hose → Turbocharger → Hose → Intercooler → Hose → Engine
Exhaust System: Turbocharger → Expansion Joint → Muffler → Exhaust Pipe
Cooling System: Radiator → Hose → Thermostat → Water Pump → Diesel Engine → Hose → Radiator
Throttle Control System: Stepper Motor → Reducer → Worm Gear Drive → Throttle Cable → Diesel Engine Throttle → High Idle and Low Idle Limit Switches
Fuel System:
- Inlet System: Fuel Tank → Hose → Hand Fuel Pump → Coarse Filter → Fine Filter → Diesel Engine
- Return System: Diesel Engine → Hose → Fuel Tank (Return volume is relatively large, used for partial cooling)
