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The Kobelco SK70 is a widely used compact hydraulic excavator, designed for various construction and excavation tasks. Known for its efficiency and maneuverability, it is particularly popular in urban construction projects and smaller jobs where space is limited. However, like any complex piece of machinery, the Kobelco SK70 may experience technical problems, particularly with its hydraulic system. One such issue that has been reported is a malfunction where the right track, boom up, and bucket curl functions only work when another function is engaged. This article will delve into the potential causes of this problem and offer troubleshooting advice.
Overview of the Kobelco SK70 Excavator
The Kobelco SK70 is part of the SK series of compact excavators that are engineered for high performance and reliability. Designed for both digging and lifting tasks, the SK70 is equipped with a powerful engine and a robust hydraulic system. It is commonly used for trenching, material handling, and digging in construction sites, especially in tight spaces where larger machines cannot operate efficiently.
With its high operating weight and compact dimensions, the SK70 provides excellent stability and power while maintaining the agility required for urban construction and small-scale excavations. The hydraulic system, in particular, is a key feature, offering precise control for a range of operations, from lifting materials to digging and grading.
The Hydraulic System on the Kobelco SK70
At the core of the Kobelco SK70’s functionality is its hydraulic system, which powers various key functions including the arm, boom, bucket, and tracks. The system works by utilizing hydraulic fluid to transfer power to different hydraulic cylinders, allowing the operator to control the movement of different components. The hydraulic pump generates fluid pressure, which is then directed to specific hydraulic circuits to control functions like the boom’s up and down movement, the bucket's curl, and track movements.
Symptoms of the Problem
The issue in question arises when the operator finds that certain functions—specifically the right track, boom up, and bucket curl—only work if another function is already in use. This can manifest in several ways:
Several potential factors can cause such malfunctions in the Kobelco SK70 hydraulic system. Below are the most common causes that should be investigated:
1. Hydraulic Pressure Issues
Hydraulic systems rely on maintaining consistent pressure to function properly. If there is a drop in pressure, certain functions may not respond as expected. This could be due to:
The hydraulic system relies on multiple valves and lines to direct fluid to the various actuators. If there are blockages, leaks, or damaged components within these lines or valves, fluid flow can be impeded.
Modern excavators like the Kobelco SK70 often have integrated control systems that coordinate hydraulic operations. If there is an issue with the electrical system, such as a faulty sensor or control module, it could prevent certain hydraulic functions from operating correctly unless other systems are active.
A low hydraulic fluid level is one of the simplest, yet often overlooked, causes of such malfunctions. If the fluid is low, it can result in low pressure, affecting performance. It's essential to regularly check the hydraulic fluid and ensure it is topped up to the correct level. Additionally, low fluid can cause air to enter the system, which leads to inconsistent function performance.
Troubleshooting and Solutions
To resolve the issue where certain functions only work when others are engaged, the following troubleshooting steps should be undertaken:
1. Check Hydraulic Fluid Levels
The first and simplest step is to ensure that the hydraulic fluid is at the proper level. If it’s low, top it up with the recommended hydraulic fluid and check for leaks.
2. Inspect Hydraulic Lines and Hoses
Examine all hydraulic lines, hoses, and connections for leaks or signs of damage. Replace any faulty hoses and ensure all connections are tight and properly sealed.
3. Test Hydraulic Pump Pressure
Measure the hydraulic system’s pressure to ensure it is within the manufacturer’s recommended range. If the pressure is low, the pump may need to be repaired or replaced.
4. Examine Valves and Filters
Inspect the hydraulic valves for proper operation and clean or replace any clogged filters. A clean filter ensures that fluid can flow freely through the system, maintaining the correct pressure for all functions.
5. Check the Electrical and Control Systems
Verify the functionality of all sensors and control components. If any electrical systems are malfunctioning, they may need to be recalibrated or replaced. It’s also advisable to check for any error codes that the excavator's computer system might have stored, which can provide insight into the issue.
6. Consult the Service Manual
If all else fails, consult the service manual for more detailed guidance on troubleshooting the hydraulic system. If the issue persists, it might be necessary to have the system inspected by a professional technician.
Conclusion
Hydraulic issues on the Kobelco SK70, such as functions working only when another function is in use, are usually caused by issues with hydraulic pressure, fluid flow, or the control system. By following the troubleshooting steps outlined above, operators can often resolve the issue without extensive repairs. However, if the problem persists, professional assistance may be necessary to restore full functionality. Proper maintenance and regular inspections of the hydraulic system are essential to prevent such issues and ensure the Kobelco SK70 operates at peak performance for years to come.
Overview of the Kobelco SK70 Excavator
The Kobelco SK70 is part of the SK series of compact excavators that are engineered for high performance and reliability. Designed for both digging and lifting tasks, the SK70 is equipped with a powerful engine and a robust hydraulic system. It is commonly used for trenching, material handling, and digging in construction sites, especially in tight spaces where larger machines cannot operate efficiently.
With its high operating weight and compact dimensions, the SK70 provides excellent stability and power while maintaining the agility required for urban construction and small-scale excavations. The hydraulic system, in particular, is a key feature, offering precise control for a range of operations, from lifting materials to digging and grading.
The Hydraulic System on the Kobelco SK70
At the core of the Kobelco SK70’s functionality is its hydraulic system, which powers various key functions including the arm, boom, bucket, and tracks. The system works by utilizing hydraulic fluid to transfer power to different hydraulic cylinders, allowing the operator to control the movement of different components. The hydraulic pump generates fluid pressure, which is then directed to specific hydraulic circuits to control functions like the boom’s up and down movement, the bucket's curl, and track movements.
Symptoms of the Problem
The issue in question arises when the operator finds that certain functions—specifically the right track, boom up, and bucket curl—only work if another function is already in use. This can manifest in several ways:
- Delayed Response: The operator might engage the boom up or bucket curl function, only to find there is a delay or no response unless they engage another function, such as the left track or arm.
- Inconsistent Functioning: Sometimes, the functions will work intermittently, operating only when another part of the hydraulic system is being used. This can make precise movements and tasks more challenging.
- Lack of Full Functionality: In some cases, certain hydraulic movements might not be possible unless other functions are engaged simultaneously, significantly reducing the machine’s efficiency and ease of operation.
Several potential factors can cause such malfunctions in the Kobelco SK70 hydraulic system. Below are the most common causes that should be investigated:
1. Hydraulic Pressure Issues
Hydraulic systems rely on maintaining consistent pressure to function properly. If there is a drop in pressure, certain functions may not respond as expected. This could be due to:
- Faulty Hydraulic Pump: The pump that circulates hydraulic fluid could be malfunctioning, leading to insufficient pressure for the system. If the pump is not delivering adequate pressure, some functions may only work when additional hydraulic circuits are in use.
- Clogged Hydraulic Filters: Filters are essential for keeping the hydraulic fluid clean and free of debris. If the filters become clogged, fluid flow could be restricted, leading to pressure drops that affect specific functions.
- Damaged Pressure Relief Valve: The pressure relief valve ensures that the system does not exceed safe pressure levels. If it is malfunctioning or stuck, it may not regulate pressure properly, causing some circuits to be starved of fluid.
The hydraulic system relies on multiple valves and lines to direct fluid to the various actuators. If there are blockages, leaks, or damaged components within these lines or valves, fluid flow can be impeded.
- Leaking or Damaged Hoses: Hydraulic hoses that are cracked, pinched, or leaking can cause fluid loss, affecting the pressure needed for certain functions.
- Sticking Valves: A malfunctioning valve could cause inconsistent fluid flow. If a valve is not switching properly, the fluid might not be routed correctly to the intended function, and it might only activate when another function is in use.
Modern excavators like the Kobelco SK70 often have integrated control systems that coordinate hydraulic operations. If there is an issue with the electrical system, such as a faulty sensor or control module, it could prevent certain hydraulic functions from operating correctly unless other systems are active.
- Faulty Sensors or Wiring: Sensors that provide input to the control system might be faulty or disconnected, preventing the operator from activating certain hydraulic functions independently.
- Control Panel Malfunctions: The issue could also be linked to a malfunction in the operator’s control panel or joystick, causing it to improperly coordinate hydraulic functions.
A low hydraulic fluid level is one of the simplest, yet often overlooked, causes of such malfunctions. If the fluid is low, it can result in low pressure, affecting performance. It's essential to regularly check the hydraulic fluid and ensure it is topped up to the correct level. Additionally, low fluid can cause air to enter the system, which leads to inconsistent function performance.
Troubleshooting and Solutions
To resolve the issue where certain functions only work when others are engaged, the following troubleshooting steps should be undertaken:
1. Check Hydraulic Fluid Levels
The first and simplest step is to ensure that the hydraulic fluid is at the proper level. If it’s low, top it up with the recommended hydraulic fluid and check for leaks.
2. Inspect Hydraulic Lines and Hoses
Examine all hydraulic lines, hoses, and connections for leaks or signs of damage. Replace any faulty hoses and ensure all connections are tight and properly sealed.
3. Test Hydraulic Pump Pressure
Measure the hydraulic system’s pressure to ensure it is within the manufacturer’s recommended range. If the pressure is low, the pump may need to be repaired or replaced.
4. Examine Valves and Filters
Inspect the hydraulic valves for proper operation and clean or replace any clogged filters. A clean filter ensures that fluid can flow freely through the system, maintaining the correct pressure for all functions.
5. Check the Electrical and Control Systems
Verify the functionality of all sensors and control components. If any electrical systems are malfunctioning, they may need to be recalibrated or replaced. It’s also advisable to check for any error codes that the excavator's computer system might have stored, which can provide insight into the issue.
6. Consult the Service Manual
If all else fails, consult the service manual for more detailed guidance on troubleshooting the hydraulic system. If the issue persists, it might be necessary to have the system inspected by a professional technician.
Conclusion
Hydraulic issues on the Kobelco SK70, such as functions working only when another function is in use, are usually caused by issues with hydraulic pressure, fluid flow, or the control system. By following the troubleshooting steps outlined above, operators can often resolve the issue without extensive repairs. However, if the problem persists, professional assistance may be necessary to restore full functionality. Proper maintenance and regular inspections of the hydraulic system are essential to prevent such issues and ensure the Kobelco SK70 operates at peak performance for years to come.
