日立ZX330ショベルが回転しないときの対処法

Hitachi excavators are renowned for their reliability and efficiency in heavy-duty construction tasks. However, after extensive use, even the most robust machinery can encounter issues. One common issue faced by the Hitachi ZX330 excavator is the inability to rotate. In this blog post, we will delve into a real-world scenario involving a Hitachi ZX330 excavator with over 15,000 hours of operation that suddenly lost its ability to rotate. We will explore the troubleshooting steps taken, the potential causes identified, and the solutions implemented to resolve the issue.

Initial Symptom Analysis

The Hitachi ZX330 excavator in question exhibited a specific problem: it could not rotate to the left or right at all. However, all other functions of the excavator were operating normally. This initial observation suggested that the main working pump of the excavator was functioning correctly, and the issue was isolated to the rotation mechanism.

Systematic Troubleshooting Approach

To diagnose and resolve the issue efficiently, a systematic approach was adopted, starting from the simplest potential causes to the more complex ones. Here are the detailed steps taken:

Step 1: Pressure Measurement

The first step involved measuring the hydraulic pressure of the pump during rotation. The normal pressure for the rotation function should be around 30 MPa. However, the measured pressure was only 8 MPa, indicating a significant discrepancy. This substantial difference suggested a severe leak in the hydraulic circuit controlling the rotation.

Potential Causes of the Issue

Given the symptoms and initial findings, four potential causes were identified:

1. Low Pilot Pressure: Insufficient pilot pressure could prevent the main control valve from opening.
2. Stuck Main Control Valve Spool: The spool of the main control valve responsible for rotation could be stuck.
3. Stuck or Broken Replenishing Valve in the Rotation Motor: The replenishing valve could be stuck, or its spring could be broken, leading to a loss of replenishing function.
4. Scratches on the Distribution Plate of the Motor: Scratches on the contact surface of the motor’s distribution plate could cause internal leaks between the supply and return circuits.

Detailed Troubleshooting Steps About Hitachi ZX330 Excavator

Step 2: Checking Pilot Pressure

To rule out low pilot pressure, the pilot oil line of the boom was swapped with the pilot oil line of the rotation mechanism. The rotation handle was then operated to see if the boom’s function was affected. The boom operated normally, indicating that the pilot pressure for the rotation function was normal. This eliminated the first potential cause.

Step 3: Inspecting the Main Control Valve

Next, the main control valve spool was disassembled and inspected for any signs of abnormal wear or sticking. The inspection revealed no issues with the valve spool, ruling out the second potential cause. This indicated that the problem was not with the multi-way valve.

Step 4: Examining the Swing Motor

The focus then shifted to the swing motor, specifically the replenishing valve. Upon inspection, the replenishing valve was found to be in good condition, with no signs of sticking or broken springs. This eliminated the third potential cause.

To further investigate, the rear end cap of the motor was removed, revealing a damaged bearing. This led to the complete disassembly of the motor, which uncovered extensive damage to the distribution plate, slippers, and other components. The swing motor in question was a swashplate-type fixed displacement motor, and the damaged bearing was identified as the primary cause of the motor’s failure. Given the extensive hours of operation, the bearing had exceeded its service life, leading to the motor’s overall damage.

Final Solution and Preventative Measures

Replacing Damaged Components: The damaged components of the swing motor, including the distribution plate, slippers, and bearings, were replaced. This restored the motor to its proper functioning state.

定期メンテナンス: This case underscored the importance of regular maintenance, especially for high-load components like hydraulic pumps and motors. Bearings, in particular, should be replaced periodically to prevent such failures. Regular maintenance schedules and checks can help identify wear and tear early, preventing costly downtime and repairs.

結論

The inability of the Hitachi ZX330 excavator to rotate was ultimately traced back to a damaged bearing in the swing motor, leading to extensive internal damage. By systematically troubleshooting the issue, starting with pressure measurements and progressing through potential causes, the issue was effectively diagnosed and resolved. This case highlights the critical importance of regular maintenance and the timely replacement of high-load components to ensure the longevity and reliability of heavy machinery.

I hope this detailed troubleshooting guide helps you in managing similar issues with your excavator. If you have any questions or need further assistance, feel free to reach out!

Q&A

1. Q: What is the operating weight of the Hitachi ZX330 excavator?

• A: The operating weight of the Hitachi ZX330 excavator is approximately 32,000 kg (70,548 lbs).

1. Q: What スイングベアリング does the Hitachi ZX330 excavator use?

• A: A: The Hitachi ZX330 excavator typically uses a single-row, four-point contact ball bearing as its swing bearing. This type of bearing is designed to handle axial, radial, and moment loads simultaneously, providing smooth and reliable rotation for the upper structure of the excavator.
• The Hitachi ZX230 excavator is a powerful and reliable machine designed for a variety of construction and excavation tasks. One of the critical components that ensure the smooth operation of this excavator is its swing bearing. The swing bearing, identified by part number 9159646, is engineered to provide exceptional performance and durability. Below are the detailed specifications of this essential component:
• Specifications for Swing Bearing (Part Number 9159646)
• Outer Diameter: 1416 mm
• Inside Diameter: 1137 mm
• Total Height: 110 mm
• Outer Height: 84 mm
• Inner Height: 97 mm
• Outer Hole Parameters: 36-Ф2
• Inner Hole Parameters: 36-M22*1.5
• Number of Teeth: 83
• This swing bearing is meticulously crafted to offer high precision and reliability, ensuring that the Hitachi ZX230 excavator can perform its tasks with maximum efficiency and minimum downtime.

1. Q: What is the maximum digging depth of the Hitachi ZX330 excavator?

• A: The maximum digging depth of the Hitachi ZX330 excavator is approximately 7.38 meters (24 feet 3 inches).

1. Q: What are some common signs that the swing motor on a Hitachi ZX230 excavator might be failing?

• A:
• 異音： Grinding, whining, or clunking sounds during operation can indicate internal issues such as worn gears or bearings.
• Slow or Jerky Movement: If the swing motor is not operating smoothly, you might notice delays, slow responses, or jerky movements when trying to rotate the upper structure.
• オーバーヒート： Excessive heat coming from the swing motor can be a sign of internal friction, insufficient lubrication, or hydraulic fluid issues.
• 作動油の漏れ： Visible leaks around the swing motor area can indicate damaged seals or connections, leading to decreased performance.
• Reduced Power: A noticeable drop in the swing motor’s power or efficiency can be a sign of internal wear or damage.