Hydraulic principle reference for two-end busy application

The backhoe loader is a single device composed of three construction equipment. Commonly known as "busy at both ends".
During construction, the operator only needs to rotate the seat to change the working end. The main reason why excavators and loaders appear on all construction sites is that all kinds of works need to excavate and carry soil. For example, ditches need to be excavated to lay pipelines and underground cables, lay the foundation for buildings and establish drainage systems.
Although many other tools can also complete such work, the backhoe loader can greatly improve efficiency. In comparison, compared with large single-function equipment (such as crawler excavator), the excavator loader is more compact. And they can also move around on various construction sites, and even run on the road. Although some small loaders and excavator equipment may be smaller than the backhoe loader, the use of backhoe loader will save a lot of time and money if the contractor needs to carry out both excavation and loading operations. Busy at both ends, telescopic loader, underground loader
Transmission shift, steering and boom confluence, pilot oil source control and external multi-function accessories, etc. The following detailed scheme and schematic diagram are for your reference:
Transmission shift control
The clutch cylinder of each gear is controlled by the electric proportional reducing overflow valve
Control forward and backward with electric proportional reducing relief valve
Off-bridge control with electromagnetic directional valve
Pressure: 2 MPa
Flow: 30 l/min
Steering and boom merge control
Realize the combination of steering pump flow and boom flow
Control oil circuit switching with boom pressure signal
Pressure: 35 MPa
Flow: 265 l/min
Crushing priority control
The priority valve gives priority to the control oil circuit of the crushing tool
The remaining flow is distributed to the lower multi-way valve
Control priority by solenoid valve
Relief valve controls priority port pressure
Pressure: 35 MPa
Flow: 379 l/min
Pilot oil source control
Provide a continuous and stable pilot oil source for the pilot handle
The pressure of the pilot oil source is controlled by the relief valve
Stabilize voltage and reduce vibration with accumulator
Pressure: 4.5 MPa
Flow: 30 l/min
Stabilizer foot
Other additional components commonly seen on backhoe loaders include two stabilizer feet behind the rear wheels. These feet are critical to the operation of the excavator. When the excavator is performing the excavation operation, the feet can absorb the impact of the weight. If there is no stable leg, the weight of heavy load or the downward force generated when digging will damage the wheel hub and tire, and the whole tractor will continue to bounce. The stabilizer foot can keep the tractor stable and minimize the impact force generated by the excavator during excavation. The stable foot can also fix the tractor so that it will not slide into the ditch or cave to operate safely
1. Before digging, the bucket mouth and legs of the loader shall be fixed with the ground, so that the front and rear wheels are slightly off the ground, and the level of the machine body shall be maintained to improve the stability of the machine. Before excavation, the loading bucket shall be turned over, with the bucket mouth facing the ground, and the front wheel slightly off the ground, the brake pedal shall be stepped down and locked, and then the outrigger shall be extended to make the rear wheel off the ground and maintain the horizontal position.
2. If the boom is suddenly braked in the middle of lowering, the impact force caused by its inertia will damage the digging device, and can damage the stability of the machine, resulting in a tipping accident. During operation, the operating handle shall be stable and shall not move sharply; Do not brake halfway when the boom is lowering. Do not use high gear when digging. The rotation shall be smooth, and shall not be hit and used to compact the side of the groove. The buffer block at the rear end of the boom shall be kept intact; In case of damage, it shall be repaired before use. When shifting, the excavation device should be placed in the middle transportation state, the outrigger should be folded, and the lifting arm should be lifted before moving.
3. Before loading, the slewing mechanism of the digging device should be placed in the middle position and fixed with a pull plate. Low gear shall be used during loading. When lifting the bucket lift arm, the floating position of the valve should not be used. The distribution valve of the hydraulic control system is divided into the front four valves and the rear four valves. The front four valves operate the outrigger, lifting arm, loading bucket, etc., and are used for outrigger telescoping and loading operations; The rear four valves operate the bucket, swing, boom and handle for swing and excavation operations. The power performance of the machine and the capacity of the hydraulic system are not allowed or possible to carry out loading and excavation operations at the same time.
4. When the front four valves work, the rear four valves shall not work at the same time. During driving or operation, it is forbidden to ride or stand on the excavator loader anywhere except outside the driver's cab.
5. Generally, the backhoe loader uses a wheeled tractor as the main engine, and is equipped with loading and digging devices at the front and rear to increase the mechanical length and weight by more than. Therefore, high-speed or sharp turns should be avoided during driving to prevent accidents. Do not slide in neutral when going downhill. When the hydraulic piston rod of the bucket and handle is kept in the fully extended position, the bucket can be close to the boom, and the digging device is in the shortest state, which is conducive to driving. When driving, the outrigger should be fully retracted, the digging device should be firmly fixed, the loading device should be lowered, and the bucket and handle hydraulic piston rod should be kept in the fully extended position.
6. After the wheeled tractor is refitted into a backhoe loader, the weight of the machine increases a lot. In order to reduce the damage of the tire under heavy load, the rear wheel shall be taken off the ground when parking. When the parking time exceeds, the outriggers shall be supported to make the rear wheels off the ground; When the parking time exceeds, the rear wheels shall be lifted off the ground and supported by cushion blocks under the rear suspension.