A 70HP-120HP farm agriculture tractor's hydraulic system is a crucial part that enables the tractor to perform various operations efficiently.
The following is an introduction to its components, working principles, and features:
Main Components
Power - generating Components
Main Hydraulic Pump: It is the core component of the hydraulic system, which converts the mechanical energy of the engine into hydraulic pressure energy.
For example, in John Deere's 7010 series tractors, the main hydraulic pump is a variable - displacement axial piston pump, with a maximum displacement of 41 cubic centimeters per revolution, directly driven by the engine crankshaft through a gear shaft.
Control Components
Distributor: Also known as the pilot valve, it is used to control the pressure, flow, or flow direction of the oil in the system. For instance, the lift control valve and selection control valve in the hydraulic system of John Deere tractors can control the lifting and operation of agricultural implements.
Pressure - limiting Valve: It is used to limit the maximum pressure in the hydraulic system to prevent the system from being damaged due to excessive pressure.
Execution Components
Rear - lifting Cylinder: It is used to lift rear - mounted agricultural implements, such as plows and harvesters.
Front - steering Cylinder: It is responsible for the steering operation of the tractor, ensuring the flexibility and maneuverability of the tractor.
Auxiliary Components
Fuel Tank: It is used to store hydraulic oil, providing a sufficient oil source for the hydraulic system.
Filter: It is used to filter the hydraulic oil, removing impurities and pollutants in the oil to ensure the cleanliness of the oil and the normal operation of the hydraulic system.
Hydraulic Oil Pipe: It is used to connect each component of the hydraulic system, transmitting hydraulic oil.
Working Principles
In a closed - center hydraulic system, such as that of John Deere's 7010 series tractors, all hydraulic functions must send a load - sensing signal to the main hydraulic pump to obtain corresponding pressure compensation.
When the system does not require oil pressure, theoretically, when there is zero load sensing, the pump flow is correspondingly reduced, only ensuring the relatively normal operating oil pressure in the system (about 400 - 500 psi).
When there is a load in the system and a certain hydraulic component is required to start working, for example, when connecting a pipeline on the SCV for plow turning, a load - sensing signal will be transmitted to the main hydraulic pump, and the main hydraulic pump will quickly work according to the system requirements to provide the system with at least a certain amount of oil pressure.
The pressure and flow control valve body in the main hydraulic pump will prevent the oil pressure of the main hydraulic pump from exceeding a certain value (such as 3000 psi).
Features
High Efficiency: The hydraulic system of tractors in this power range can quickly respond to the operation commands of agricultural implements, improving work efficiency.
For example, YTO - MG700 tractors adopt intelligent hydraulic systems that can actively match hydraulic power and flow, allowing for sufficient hydraulic pressure at any engine speed.
Large Lifting Capacity: It can meet the lifting requirements of various agricultural implements. For example, some 70HP tractors have a lifting capacity of ≥12.3kN at 610mm.
Good Adaptability: It can work normally in different working environments and terrains.
The hydraulic components have high strength and reliability. For example, the hydraulic pump of John Deere's 6B series tractors has a cast - iron housing and integrated gears and shafts, which can adapt to harsh working conditions such as bumpy roads.
