Reference of hydraulic principle for busy application of both ends

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 turn the seat to change the working end. The main reason why backhoe loaders appear on all construction sites is that various projects need to excavate and move soil. For example, trenches need to be dug to route pipes and underground cables, to lay foundations for buildings, and to establish drainage systems.

Although many other tools can also complete such tasks, the backhoe loader can greatly improve efficiency. In comparison, compared with large single-function equipment (such as crawler excavators), the backhoe loader is compact. And they can also move around on various construction sites and even run on highways. Although some small loaders and excavators may be smaller than backhoe loaders, if the contractor has to carry out both excavation operations and loading operations, the use of backhoe loaders can save a lot of time and money. Busy at both ends, telescopic loaders, underground loaders

Gearbox shifting, steering and boom merging, pilot oil source control and external multiple function attachments, etc. The following detailed schemes and schematic diagrams are for your reference:

Gearbox shift control

Control each gear clutch cylinder with electric proportional pressure relief valve

Control forward and backward with electric proportional pressure relief valve

Use electromagnetic reversing valve to realize off-bridge control

Pressure: 2 MPa

Flow rate: 30 liters/min

Steering and boom merging control

Realize the confluence of steering pump flow and boom flow

Control oil circuit switching with boom pressure signal

Pressure: 35 MPa

Flow rate: 265 liters/min

Priority control of crushing

Priority valve gives priority to the control oil circuit of the broken drill rod

The rest of the flow is distributed to the lower multi-way valve

Priority control by solenoid valve or not

Overflow valve controls priority port pressure

Pressure: 35 MPa

Flow rate: 379 liters/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

Use accumulator to realize voltage stabilization and shock absorption

Pressure: 4.5 MPa

Flow rate: 30 liters/min

Stabilizing feet

Other additional components generally found on backhoe loaders include two stable feet behind the rear wheels. These feet are essential to the operation of the excavator. When the excavator performs digging operations, the feet can absorb the impact of weight. If there is no stable foot, the weight of the heavy load or the downward force generated when digging the ground will damage the wheels and tires, and the entire tractor will continue to bounce. The stable feet can keep the tractor stable and minimize the impact force generated by the excavator when digging. Stable feet can also fix the tractor so that it will not slip into the ditch or cave for safe operation technology

1. Before excavating the backhoe loader, fix the mouth and outriggers of the loading bucket with the ground, keep the front and rear wheels slightly off the ground, and keep the level of the fuselage to improve the stability of the machine. Before digging, turn the loading bucket over so that the mouth of the bucket is facing the ground, and the front wheel is slightly off the ground, step on and lock the brake pedal, and then extend the outrigger to keep the rear wheel off the ground and maintain a horizontal position.

2. If the boom is suddenly braked while it is lowering, the impact force caused by its inertia will damage the excavating device, and can destroy the stability of the machine and cause a tipping accident. During operation, the control handle should be stable and not move sharply; when the boom is lowered, it should not be braked halfway. Do not use high gear when digging. The rotation should be stable, not to hit and be used to smash the side of the groove. The buffer block at the rear end of the boom should be kept intact; if it is damaged, it should be repaired before use. When shifting, the digging device should be in the intermediate transportation state, the outriggers should be retracted, and the lifting arm should be lifted before proceeding.

3. Before loading operation, the slewing mechanism of the excavating device should be placed in the middle position and fixed with a pull plate. During the loading process, a low gear should be used. The floating position of the valve should not be used when the bucket lift arm is being lifted. The distribution valves of the hydraulic control system are divided into the front four valves and the rear four valves. The first four valves control the outriggers, lifting arms and loading buckets, etc., which are used for outrigger extension and loading operations; the rear four valves operate the bucket, swing, and move Arms and bucket handles, etc., are used for slewing and excavating operations. The power performance of the machinery and the ability of the hydraulic system do not allow or impossible to carry out loading and digging operations at the same time.

4. When the first four valves are working, the last four valves must not work at the same time. During driving or operation, it is strictly forbidden to ride or stand on any part of the backhoe loader except outside the cab.

5. The general backhoe loader uses a wheeled tractor as the main engine, and the front and rear are equipped with loading and digging devices to increase the length and weight of the machine. Therefore, avoid high speeds or sharp turns during driving to prevent accidents. Do not slide in neutral when going downhill. When the hydraulic piston rod of the bucket and the bucket handle is kept in the fully extended position, the bucket can be moved closer to the boom, and the excavating device is in the shortest state, which is conducive to driving. When driving, the outriggers should be fully retracted, the excavating device should be firmly fixed, the loading device should be lowered, and the bucket and bucket handle hydraulic piston rod should be kept in a fully extended position.

6. After the wheeled tractor is converted into a backhoe loader, the machine weight has increased a lot. In order to reduce the damage of the tire under heavy load, the rear wheel should be off the ground when parking. When the parking time exceeds, the outriggers should be raised to keep the rear wheels off the ground; when the parking time exceeds, the rear wheels should be off the ground, and the rear suspension should be supported by cushion blocks.