Troubleshooting Jerky Hydraulic Operations on Bobcat E85 Excavators

The Bobcat E85 is a powerful and versatile mini excavator known for its high performance in both urban and rugged environments. However, like all machinery, it can experience mechanical issues from time to time. One such issue that has been reported by operators is jerky or erratic hydraulic operations. This problem can significantly affect the efficiency of the machine, making it difficult to control during operation. Understanding the causes and solutions to this issue is key to restoring smooth and responsive hydraulic functions.

Common Causes of Jerky Hydraulic Movements

Hydraulic systems are a critical part of the Bobcat E85’s operation, controlling functions like the boom, arm, and bucket. When the hydraulic system malfunctions, it can lead to jerky or unpredictable movements. There are several potential causes of this issue:

1. Low Hydraulic Fluid Levels

The most common cause of jerky hydraulic operations is insufficient hydraulic fluid. The fluid serves as the medium that transmits power from the hydraulic pump to the various hydraulic cylinders, ensuring smooth and consistent movement. If the fluid level drops too low, the pump can struggle to generate the necessary pressure, leading to uneven movements and jerky motions.

Solution: Check the hydraulic fluid level regularly and top it up if necessary. Ensure that the fluid is of the correct type and viscosity for the Bobcat E85, as recommended by the manufacturer.

2. Contaminated Hydraulic Fluid

Contaminants in the hydraulic fluid, such as dirt, water, or metal particles, can cause blockages or excessive wear in the hydraulic system. Contaminated fluid can clog filters and reduce the efficiency of the pump, leading to jerky or inconsistent movements.

Solution: Regularly change the hydraulic fluid and replace the filters according to the manufacturer’s maintenance schedule. If you suspect contamination, flush the system and replace the fluid and filters to restore performance.

3. Air in the Hydraulic System

Air trapped within the hydraulic system can also cause erratic or jerky operation. Air bubbles reduce the efficiency of the hydraulic fluid, making it harder for the system to generate smooth and consistent pressure. This often occurs after a fluid change, or if there are leaks in the hydraulic lines.

Solution: Bleed the hydraulic system to remove any trapped air. Ensure that all connections are tightly secured and check for any leaks that may allow air into the system.

4. Worn or Damaged Hydraulic Components

Over time, hydraulic components like pumps, valves, and cylinders can wear out or become damaged. Worn seals, for example, can cause hydraulic fluid to leak, reducing system pressure and causing jerky movements. Additionally, if a hydraulic pump or valve becomes clogged or malfunctioning, it can lead to irregular flow of hydraulic fluid, resulting in jerky or hesitant movements.

Solution: Inspect hydraulic components regularly for signs of wear or damage. Replace any worn seals or components as needed, and ensure that the pump and valves are functioning properly.

5. Faulty Hydraulic Control Valve

The hydraulic control valve is responsible for directing the flow of fluid to the various hydraulic cylinders. A malfunctioning valve can cause improper fluid distribution, leading to jerky or erratic movements. A common issue with these valves is internal wear or blockage, which can prevent smooth control.

Solution: Inspect the hydraulic control valve for signs of wear or damage. If the valve is faulty, it may need to be replaced or repaired by a professional.

6. Incorrect Pump Pressure

If the hydraulic pump is not generating the correct amount of pressure, it can cause the system to behave erratically. Overpressure or underpressure can both result in poor hydraulic performance, with jerky or hesitant movements as the system struggles to maintain the required pressure.

Solution: Check the hydraulic pump’s pressure using a pressure gauge. If the pressure is too low or too high, adjust the pump settings according to the Bobcat E85’s specifications.

Additional Factors to Consider

While the above are some of the most common causes of jerky hydraulic operations, it’s important to also consider a few additional factors:

1. Temperature Effects

Hydraulic fluid viscosity can change depending on the temperature. In cold conditions, the fluid may become thicker, which can make the system sluggish. Conversely, in hot conditions, the fluid can thin out, reducing its ability to transmit power effectively.

Solution: Ensure that the machine operates within the recommended temperature range. If operating in extreme temperatures, use hydraulic fluid specifically designed for those conditions.

2. Operator Technique

Sometimes, jerky hydraulic movements can be caused by operator technique, especially when controlling the excavator’s various functions. Rapid movements or jerky lever operations can strain the hydraulic system and create a noticeable erratic response.

Solution: Train operators on the importance of smooth and deliberate control when operating the excavator. Using the hydraulic functions gradually and in a controlled manner can prevent unnecessary strain on the system.

3. Electrical or Sensor Malfunctions

The Bobcat E85 uses sensors and electronic control systems to manage its hydraulic operations. If there is an issue with the sensors or electrical connections, it could cause irregular signals to the hydraulic components, leading to jerky or unresponsive behavior.

Solution: Check the electrical connections and sensor calibration. If there are any faults or error codes, troubleshoot or reset the system according to the operator’s manual.

Troubleshooting and Preventive Measures

Once you’ve identified the potential causes, it’s time to perform some troubleshooting and implement preventive measures to avoid future issues:

1. Regular Fluid Checks and Maintenance: Always maintain proper hydraulic fluid levels and regularly change the fluid and filters. Use clean, high-quality fluid and avoid cross-contamination.
2. Inspect for Leaks and Damaged Components: Check hoses, fittings, and cylinders for leaks or wear. Replace any damaged parts promptly to avoid further issues.
3. Monitor System Pressure: Keep track of the pump’s pressure and ensure it matches the manufacturer’s specifications.
4. Train Operators: Proper operator training is essential for maintaining hydraulic system health. Smooth and steady operation will reduce strain on the system and increase its lifespan.
5. Regular Professional Inspections: Schedule routine inspections with a qualified mechanic to identify potential issues early, before they lead to major malfunctions.

Conclusion

Jerky hydraulic movements on the Bobcat E85 can be frustrating, but by following a systematic approach to diagnosing the issue and performing regular maintenance, you can restore smooth operation to the machine. Regular fluid checks, proper maintenance, and addressing issues like air in the system or hydraulic component wear are all key to ensuring the longevity and reliability of your excavator. By understanding the common causes and taking preventive steps, you can avoid hydraulic issues and keep your Bobcat E85 running at peak performance.