Common Causes and Remedies for Hydraulic Breaker Malfunctions

Q1, Why the oil become black?

The contamination of an excavator’s hydraulic system with black oil is not solely caused by dust infiltration but also by improper grease application.

For instance, when the gap between the bushing and the chisel exceeds 8 millimeters (if a pinky finger can fit through), it is advisable to replace the bushing. On average, for every two lower bushings replaced, one upper bushing should also be replaced.

When replacing hydraulic components such as hoses, steel pipes, and return oil filters, it is essential to clean any dust or debris from the connection points before loosening and replacing them.

When applying grease, the hydraulic breaker should be lifted, and the chisel should be pressed into the piston. Each application should only use half a standard grease gun. (If the chisel is not pressed tightly during greasing, the grease will accumulate at the upper limit of the chisel slot. When the chisel operates, the grease will be forced directly to the main oil seal of the breaker. With the piston’s reciprocating motion, the grease will be carried into the breaker’s cylinder and subsequently mix with the hydraulic oil, causing the hydraulic oil to degrade and turn black.)

Remedies:

1. Adopt the correct posture when applying grease.

2. Install a return oil filter device.

3. Install a water spray device to reduce external dust.

4. Replace the bushings in a timely manner if there is excessive wear.

5. Regularly inspect the check valve for damage or blockage.

6. Replace the dust seals promptly.

7. Use the hydraulic breaker correctly (avoid frequent off-center strikes).

8. Ensure the chisel size matches the bushings.

Q2, What causes the hydraulic breaker to lose its power?

Insufficient nitrogen pressure, inadequate oil pressure in the pipelines, and factors such as local weather conditions and the hardness of the ore all contribute to the issue.

Remedies:

1. First, check the nitrogen pressure.

2. Inspect the static oil pressure.

3. Ensure the working oil volume is sufficient.

4. Verify the chisel size and check if the guard plate screws are loose.

5. Examine the bushing clearance and wear condition.

6. Test if the hydraulic oil is adequate.

7. Ensure the shut-off valve is fully open.

8. Tighten the locknut on the relief valve if it is loose.

If all the above are normal:

1. Insufficient pressure at pilot port A or a stuck auxiliary valve causing significant internal leakage.

2. Blockage in the main oil inlet or return line.

3. Excessive internal leakage in the piston or control valve.

4. Inadequate power source or internal leakage in the main pump.

For breakers equipped with an accumulator, also check if the accumulator diaphragm is ruptured.

Q3, Oil leakage in the hydraulic breaker.

Causes:

Oil leakage in a hydraulic breaker can stem from various sources, depending on the specific area affected.

Remedies:

1. Oil leakage at the piston:

1), Observe the routine maintenance practices and disassemble the main body for inspection. If there is a significant amount of hydraulic oil leakage and it appears murky, with a mixture of grease and hydraulic oil between the rear bushing and the piston, it is likely due to improper grease application. Replace the sealing components promptly and instruct the customer on the correct method of applying grease.

2) If hydraulic oil leakage is observed and the breaker casing is severely corroded, it may be due to improper storage over a long period. Water ingress and rust can directly damage the piston seals, leading to oil leakage. Inform the customer about the correct long-term storage method:

Release the nitrogen gas.

Insert the chisel.

Ensure that the upper part of the cylinder is elevated higher than the lower part.

By following these steps, the risk of water ingress and subsequent rust damage can be minimized, thereby protecting the seals and preventing oil leakage.

3), Observe the operating methods. If there is a significant amount of chiseling and digging, small debris and stones can be introduced into the casing, causing wear on the piston seals and leading to oil leakage. Inform the customer about the correct operating procedures to prevent such issues from recurring.

Oil leakage at the joint between the nitrogen chamber and the middle cylinder:

Cause: The “O” ring at the joint between the nitrogen chamber and the middle cylinder is worn out.

Remedy: Replace the worn “O” ring.

Oil leakage at the joint between the directional valve base and the middle cylinder:

Cause: The “O” ring at the directional valve base is damaged.

Remedy: Replace the damaged “O” ring.

Oil leakage at the connection surface between the middle cylinder and the oil pipe interface:

Cause: The “O” ring seal is worn out or the oil pipe interface is loose.

Remedy: Replace the worn “O” ring and tighten the interface to the specified torque.

Oil leakage at the joint between the middle cylinder and the upper cylinder:

Cause: The “O” ring and the backup ring are worn or damaged, and the screws on the breaker body are loose.

Remedy: Replace the worn “O” ring, seal ring, and backup ring promptly, and tighten the screws to the specified torque.

Q4, The bolt of the hydraulic breaker has fractured.

Causes:

Given the harsh working conditions of the hydraulic breaker, its components are prone to wear and tear. The frequent fracturing of bolts is, to some extent, a normal occurrence. Additionally, the powerful vibrations generated during the operation of the breaker can cause the guard plate bolts and through bolts to loosen. This results in the threads of the bolts experiencing fatigue damage, ultimately leading to their fracture. The specific reasons are as follows:

1. Deformation of the guard plate.

2. Weld detachment causing deformation.

3. Intrinsic quality issues, insufficient strength.

4. Uneven stress on a single bolt (due to lack of regular inspections).

5. External force impact.

6. Excessive pressure and vibration.

7. Improper operations such as dry firing.

Remedial Measures:

Tighten the bolts every 20 hours.

Adopt standardized operating procedures, minimizing actions such as chiseling and digging.

Q5. What are the detrimental effects of dry firing on a hydraulic breaker?

Causes:

Improper operation leads to dry firing, where the piston transmits the impact force to the chisel, which then transfers it to the chisel pin. The chisel pin, under such immense impact, is prone to fracture. When the chisel pin is struck, it disperses the force to the chisel pin cross pin, causing the cross pin to press against the inner hole of the chisel pin, leading to cracks at the edge of the inner hole and ultimately resulting in the lower cylinder body fracturing.

Frequent dry firing can cause the front body, flat pins, bolts, guard plates, boom, and chisel to crack, and can lead to oil leaks in both soft and hard hoses.

Remedial Measures:

Ensure the chisel is pressed tightly against the rock before commencing the breaking operation, maintaining an impact angle between 85 and 95 degrees.

Inform customers to adhere to the operational guidelines specified in the hydraulic breaker’s user manual.

Q6, The hydraulic breaker stop working

There are numerous reasons for the cessation of the hydraulic breaker’s operation:

For instance, if the breaker halts during work:

1, Sticking of the directional valve. Upon disassembling and inspecting the breaker, all other components were found to be intact. However, the directional valve was discovered to be sliding with difficulty and prone to sticking. After removing the valve spool, multiple scratches were observed on the valve body. (Replace the directional valve spool)

2, Improper bushing replacement. After replacing the bushing, the breaker experienced a malfunction where it ceased operation; it would not strike when pressed down but would resume striking when slightly lifted. This issue arises because the new bushing positions the piston higher, causing some small directional valve control oil passages within the cylinder to close at the initial position, leading to the directional valve’s failure and the breaker’s subsequent stoppage. (Replace with original or certified bushings)

3, Oil ingress in the rear cover. During operation, the breaker gradually loses power and eventually ceases to strike. Upon measuring the nitrogen pressure, it is found to be excessively high. After releasing the pressure, the breaker resumes striking but soon stops again, with the pressure rising once more upon measurement. Disassembly reveals that the upper cylinder is filled with hydraulic oil, preventing the piston from compressing backward, thus rendering the breaker inoperative. (Replace the sealing components)

4, Accumulator components falling into the pipeline. During inspection, deformed parts from the accumulator were found to have jammed the directional valve.

In addition to the above reasons, other potential causes include the excavator valve plate getting stuck or the O-ring on the valve plate coming out of its groove, both of which can also lead to the breaker ceasing to strike.

Q7, The impact frequency of the hydraulic breaker cannot be adjusted.

Solution: Replace the regulator O-ring.

Q8 , The newly installed hydraulic breaker fails to operate.

Possible Causes:

The hydraulic lines might be connected incorrectly. The line on the cabin side should be high pressure, while the other side should be low pressure. If installed in reverse, the breaker will not function. Additionally, the valve plate on the excavator’s multi-way valve might be stuck.

Incorrect installation of high and low-pressure hoses: the cabin side should be high pressure, the other side low.

Solution:

1. Install the hydraulic lines correctly.

2. Ensure the valve plate operates normally.

Q9, The front end of the piston is damaged.

Cause of Issue:

During operation, the breaker dropped metal fragments, which originated from the front cover. Upon disassembly, it was discovered that the striking surface at the front end of the piston was damaged. Further inspection revealed that the chisel used with the breaker was custom-made by the user. Its hardness exceeded that of the piston, leading to accelerated wear on the piston’s front end during use.

Remedial Measures:

1. Refine the piston head with a polishing machine, ensuring it remains within precise dimensional limits.

2. Advise the customer to purchase genuine parts (chisels).

Q10, How to Determine if the Chisel Breakage is a Quality Issue:

Remedial Measures:

Chisel breakage generally falls into two categories:

1.Fracture

(1) Fracture Surface: The primary indicator is the pattern on the chisel’s fracture surface. As shown in the illustration, this type of breakage is typically caused by improper operation. It is the most common type of chisel fracture. This usually results from the wear of the lower bushing, chisel, and inner bushing, which causes an abnormal striking angle and induces bending stress, leading to the chisel’s fracture. Such fractures are not covered by our warranty.

(2) Fracture Location:

This fracture exhibits no apparent external damage on the steel rod’s surface. The broken section is uneven, with fragments present in the direction opposite to the initial break.

Q11, Why is it essential to warm up the hydraulic breaker before use?

Due to the hydraulic breaker’s substantial impact force and rapid frequency, the sealing components are prone to significant wear. Warming up the machine can mitigate the wear on the oil seals. When hydraulic oil is at rest, it forms a solid-state oil film adhering between the piston and the oil seal. Warming up the breaker allows the moist hydraulic oil to flush away the relatively solid oil film, establishing a new oil film that expands the oil seal, ensuring that the piston and oil seal do not suffer initial damage.

When the breaker starts working in a cold state, the sudden influx of hot oil causes thermal expansion and contraction, which can significantly damage the oil seal. Combined with the rapid movement, this can lead to frequent oil leaks and the need for more frequent oil seal replacements. Therefore, warming up the breaker before use is beneficial for both the customer and us.

Approach:

Patiently explain to the customer the benefits of warming up the machine: it prevents oil leaks, extends the lifespan of the breaker’s wear parts, and is also advantageous for the excavator itself. Use real-life examples to illustrate the benefits, such as how cars also require warming up before use, for reasons that are self-evident.

Warm-up Procedure:

Position the breaker vertically off the ground, press the foot valve to about one-third of its travel until you see a slight vibration in the main oil inlet pipe (the pipe closest to the cab). Maintain this position for approximately 20-40 minutes.

Q12, What is the allowable clearance for replacing the guide bushing? What issues may arise if it is not replaced in a timely manner?

Approach:

Generally, the clearance should be around eight millimeters (approximately the width of a pinky finger fitting into the lower cylinder). If not replaced in a timely manner, the following issues may arise:

1. Excessive clearance between the chisel and the bushing allows dust and foreign particles to enter the cylinder during breaking operations. This can lead to wear and damage to the sealing components, resulting in oil leaks and contamination.

2. The excessive clearance causes uneven force distribution, which can damage the piston by disrupting the oil film in the middle cylinder.

3. During impact, the chisel’s tail and the piston’s striking surface may not make proper contact, ultimately damaging the chisel’s tail.

4. If the piston cannot move vertically, it will cause uneven wear on the cylinder, leading to rapid out-of-roundness. Excessive out-of-roundness will cause internal leakage, reducing the breaker’s impact force.

5. It will shorten the lifespan of both the piston and the chisel.

Q13, What is the optimal hydraulic pressure for a hydraulic breaker to function properly, and what are the potential impacts on the breaker and the excavator if the pressure is too high or too low?

For a new excavator, the typical hydraulic pressure ranges between 200-220 bar, while for an older excavator, it generally exceeds 230 bar.

If the hydraulic pressure is too low, the breaking force will be insufficient.

Conversely, if the pressure is too high, although the impact force will be substantial, it will cause significant wear and tear on the excavator’s hydraulic pump and the breaker itself. This includes potential cracking at the weld seams of the hammer’s guard plate, boom, and pressure plate. Bolts may break easily, hoses and pipes may leak, and the performance of both the excavator and the breaker will deteriorate prematurely.

Q14, What are the potential causes of air leakage?

Causes of Air Leakage:

1. Damaged or defective oil seals.

2. Damaged valve core.

3. Cracks in the upper cylinder.

4. Normal wear and tear.

Solutions:

1. Inspect the nitrogen valve for damage. Apply soapy water around the nitrogen valve and observe for bubbles when nitrogen is charged.

2. If the O-ring in the nitrogen chamber is damaged, apply soapy water at the connection between the middle cylinder and the nitrogen chamber. If bubbles appear, replace the two gas seals.

3. If bubbles appear at the oil inlet and return port, it indicates that the O-ring on the outer ring of the piston ring is damaged and needs replacement.

4. If air leaks while the breaker is in operation, it suggests that the gas seal inside the piston ring is damaged and needs replacement.

5. If air leaks at the bolts of the directional valve base and the through-bolt nuts, it is likely due to material defects such as sand holes or cracks in the nitrogen chamber body.

Q15, What are the potential consequences of oil leakage in the nitrogen chamber?

Initially, the impact is slow and lacks force, then ceases altogether. Subsequently, hydraulic oil is present within the system, and releasing nitrogen results in a misty spray of hydraulic oil.

Q16, What could cause the breaker to exhibit an unstable striking frequency?

1. Potential instability due to issues with the main unit.

2. Insufficient hydraulic oil, leading to inadequate flow.

3. Damaged relief valve.

4. Minor scoring on the piston, control valve, or auxiliary valve.

5. Inadequate pipeline pressure.

6. Blocked pipelines.

7. Instability caused by the reactive force of the material being broken.

8. Loose bolts or incorrect chisel size.

Q17: What’s the consequences of restricted return flow lead to?

1. Weak impact of the breaker.

2. Sluggish frequency.

3. Elevated oil temperature.

4. Diesel wastage.

Additionally, it can cause the breaker to exhibit an unstable striking frequency. This issue often arises when the return oil filter is not replaced within the specified time, leading to filter blockage and obstructing the return oil flow. If the return oil pipe directly feeds into the multi-way valve, prolonged operation can cause the valve to stick, resulting in rapid hydraulic oil temperature increase and diminished breaker performance.

Q18, If the hydraulic breaker pipeline is installed but lacks pressure, what should be inspected?

1. Verify if the pipeline is installed correctly.

2. Open the shut-off valve to check if there is pressure in the pipeline or if the pressure is normal.

3. Inspect whether the relief valve is damaged.

4. Ensure there is sufficient pressure at port A.

5. If all the above are normal, check if the standby valve is stuck.

Q19, What are the primary causes of a hydraulic breaker jamming, and how can they be diagnosed?

1. Scoring of the piston and directional valve.

2. Jamming of the standby valve and relief valve.

3. Insufficient hydraulic oil.

4. Obstructed oil flow, causing partial blockage.

5. Inadequate pilot pressure.

6. Excessive clearance or abnormal wear of the bushing.

When the hydraulic breaker fails to strike, first check if the nitrogen pressure is too high (excessive nitrogen pressure can hinder the piston, causing the breaker to malfunction). Next, inspect the directional valve spool for any jamming. If neither is the issue, it is likely that the piston is stuck in the cylinder (this may be accompanied by slight oil leakage).

Q20, The ingress of air into the hydraulic oil within the pipeline can lead to what consequences?

1. Cavitation is likely to occur, and in severe cases, it may cause oil leakage in certain areas.

2. Irregular impacts.

3. The hydraulic breaker may strike with insufficient force or at an abnormal frequency.

4. Abnormal damage to the pipeline and the hammer body.

Q21, What causes the presence of white indentations on the piston surface?

1. Corrosion caused by rust.

2. Improper maintenance, or lack of specialized equipment during underwater operations.

3. Prolonged operations in coastal areas, or extended periods of inactivity.

4. Incorrect storage position; the upper cylinder should be slightly elevated above the lower cylinder.