Working Principle and Precautions of Hydraulic Rock Drill

Table of Contents

The hydraulic rock drill originated in the early 1970s. Due to its superiority in technical performance and perforation efficiency, it has developed rapidly, and now it has formed various models and series with hundreds of specifications. The hydraulic rock drill is the main working mechanism of the hydraulic drill rig, but it has high technical content, complex structure, and high requirements for use and maintenance, while hydraulic drill rig is widely used in coal mine excavation, once the hydraulic rock drill breaks down, it will cause the drill rig to stop production, thus affecting the progress of the project. Therefore, understanding the working principle and precautions of the hydraulic rock drill can effectively reduce its failure rate, which is crucial to the enterprise.

What is a Hydraulic Rock Drill?

The hydraulic rock drill is a kind of rock drilling equipment with multiple functions such as impact, rotary, propulsion, and flushing with hydraulic oil as the driving force, which has the advantages of fast rock drilling speed, low power consumption, high energy utilization, high impact work, adjustable impact work, and rotational speed, good action conditions, single power and saving investment, and is widely used in road construction, infrastructure construction, mining, and other industries.

Although the operation of a hydraulic rock drill is simple, its structure is relatively complicated. What parts does it consist of?

Composition of Hydraulic Rock Drills

The hydraulic rock drill consists of an impact part, a rotating part, and a water injection tank. The impact part includes a casing, a cylinder, an accumulator, a reversing element, an impact piston, and a buffer piston. The rotary part contains the rotary motor, drive shaft, gear chamber, driving gear, drive gear, spline sleeve, and shank adapter. These parts interact with each other and cooperate with high precision, making the hydraulic rock drill more efficient in tunneling.

Working Principle of Hydraulic Rock Drill

Hydraulic rock drills work on the principle of impact crushing. When working, the piston reciprocates at a high frequency and continuously impacts the shank adapter. Under the action of the impact force, the sharp wedge-shaped drill bit crushes the rock and digs it to a certain depth, forming a dent. After the piston returns, the drill turns a certain angle, the piston moves forward, and when it hits the shank adapter again and formed a new dent. The fan-shaped rock block between the two dents is sheared by the horizontal component force generated on the drill bit. The piston continuously impacts the shank adapter, and continuously inputs compressed air or pressurized water from the center hole of the drill, discharging the rock slag out of the hole, forming a circular hole with a certain depth.

YT28 pneumatic rock drill

Through the working principle of the hydraulic rock drill, we already know that as soon as the hydraulic rock drill starts working, its impact piston will be in contact with the shank, and high-frequency reciprocating or rotary motion will occur. Coupled with the fact that hydraulic rock drills operate in a relatively harsh environment and may face varying geological conditions, what do we need to pay attention to improve the performance and service life of hydraulic rock drills?

Precautions for Hydraulic Rock Drills

1. The newly purchased rock drill is coated with a viscous anti-rust grease inside, which must be disassembled and cleaned before use. When reassembling, the surface of the moving parts should be lubricated. Once installed, check whether its operation is normal.

2. Inject lubricating oil into the automatic oiler. The container for lubricating oil should be clean and covered to prevent rock dust and dirt from entering the oiler.

3. Check the wind and water pressure at the workplace.

4. When the air pipe is connected to the rock drill, it should be deflated to blow out the dirt in the pipe. For water line, flush to clean the joint.

5. Insert the shank adapter into the rock drill head, and turn it clockwise. If it does not move, it means that the machine is jammed and should be dealt with in time.

6. Tighten the connecting bolts and check the operation of the propeller. It must be running well before it can start working.

7. For hydraulic rock drills, the hydraulic system should be required to have good sealing to prevent the hydraulic oil from being polluted and to ensure that the hydraulic oil has constant pressure.

8. When excavating, it should be turned slowly, and after the depth of the hole reaches 10-15mm, it will gradually turn into full operation.

9. The shaft thrust should be reasonably tested when drilling.

10. Regularly observe the powder discharge situation. When the powder discharge is normal, the mud flows out slowly along the orifice. Otherwise, blow the hole strongly. If it is still invalid, check the state of the water hole and the shank adapter of the drill, then check the water needle, and replace the damaged parts.

11. Pay attention to observing the oil reserve and output, and adjust the oil amount.

12. Pay attention to the sound of the machine during operation, observe its operation, find problems and deal with them in time.

13. Pay attention to the working state of the drill, and replace it in time if there is an abnormality.

14. Pay attention to the rock situation, avoid perforation along the bedding, joints, and fissures, prohibit breaking the residual rock, and observe at any time if there is the risk of roof collapsing.

15. Use the hole-opening function effectively. It is accomplished with reduced impact pressure and fixed propulsive pressure. The thrust pressure should be as low as possible to facilitate drilling on very steep rock faces and to avoid bending the drill rod.

16. Operators should be familiar with the performance and use of hydraulic rock drills and operate according to specifications. Avoid overloading or long-term continuous operation to avoid damage to the equipment. During the drilling process, it is necessary to maintain a stable advancement speed and appropriate drilling pressure to prevent excessive impact on the drill bit or rock.

17. When using a hydraulic rock drill, you should wear safety protective equipment, such as safety helmets, protective glasses, and gloves. At the same time, ensure the safety of the work area, prevent other personnel from entering the work area, and prevent accidental injuries.

18. During use, the hydraulic rock drill may experience various failures, such as leakage, stuck drill, and no impact. Upon detecting a fault, promptly cease machine operation for inspection, identifying the cause,  and addressing it immediately. For issues beyond personal resolution, seek assistance from professional maintenance personnel promptly to prevent the fault from worsening or leading to more severe consequences.

19. Establish complete equipment maintenance records and record every inspection, maintenance, and repair. It helps to detect problems with the equipment promptly and take efficient measures to solve them to ensure the proper operation of the equipment.

20. When storing and transporting hydraulic rock drills, we should pay attention to prevent collisions and impacts to avoid equipment damage. At the same time, ensure that the equipment is stored in a dry and ventilated environment to avoid moisture and corrosion.


As efficient and energy-saving drilling equipment, hydraulic rock drills play a crucial role in modern mining and tunnel construction. Understanding the working principles and precautions of hydraulic rock drills is of great significance for the correct use and maintenance of equipment and for improving drilling efficiency and quality. Only by strictly following the specifications and performing regular maintenance and inspections can the normal operation of the equipment be ensured and its service life extended. At the same time, operators should continue to improve their skills and knowledge to adapt to changing work needs and market environments.

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