Hydraulic System Maintenance on the 70D: Best Practices and Troubleshooting

[MikePhua]

Hydraulic systems are the backbone of many construction and heavy-duty equipment, including excavators like the 70D. The efficiency and power of such machines depend heavily on the proper functioning of their hydraulic systems. However, over time, wear and tear can lead to a variety of hydraulic issues, including leaks, pressure problems, and sluggish performance. This article discusses how to maintain, troubleshoot, and replace hydraulic components on a 70D excavator, ensuring that your machine continues to perform at its best.
Understanding the Hydraulic System of the 70D Excavator
The 70D excavator is equipped with a robust hydraulic system that controls key functions, including the boom, arm, bucket, and swing mechanisms. This system uses pressurized fluid to generate the power needed to lift, dig, and move heavy materials. The key components of the hydraulic system include:

• Hydraulic Pump: Transfers hydraulic fluid into the system at the necessary pressure.
  
• Hydraulic Fluid: A specially formulated oil that transmits power and lubricates the system.
  
• Hydraulic Cylinders: Convert hydraulic pressure into mechanical movement for the various moving parts of the machine.
  
• Valves: Direct the flow of fluid to specific parts of the system depending on the operator's input.
  
• Filters: Keep the hydraulic fluid clean by filtering out contaminants that can damage components.
  

Regular maintenance of these components is essential for the machine’s optimal performance. Hydraulic fluid should be checked and replaced periodically, and hydraulic filters should be cleaned or replaced to prevent clogs and wear.
Common Hydraulic Issues on the 70D Excavator
Despite regular maintenance, hydraulic systems can still face challenges, especially if the machine has been in use for several years. Here are some common hydraulic problems that 70D owners might encounter:

1. Loss of Hydraulic Pressure
   • Causes: This issue could be due to a worn-out hydraulic pump, damaged seals, or leaks in the system. A loss of pressure will lead to weak or delayed movement in the boom or arm, making it difficult to perform tasks efficiently.
     
   • Solution: Check the hydraulic pump for signs of wear or damage. Inspect all hoses and connections for leaks. If the pump or a hose is damaged, replace the component to restore full pressure.
     
2. Slow or Jerky Movements
   • Causes: Sluggish movements may occur due to dirty or contaminated hydraulic fluid, blocked filters, or air trapped in the hydraulic lines. It can also result from low fluid levels.
     
   • Solution: Start by checking the hydraulic fluid level. If it's low, top it off with the recommended fluid. Clean or replace the hydraulic filters, and bleed the system to remove any air pockets.
     
3. Hydraulic Fluid Leaks
   • Causes: Leaks in the hydraulic system are common, especially around seals or hose connections. Leaks can lead to low fluid levels and cause the system to malfunction.
     
   • Solution: Inspect all hoses and seals for leaks. Tighten any loose connections, and replace any damaged seals or hoses. Always ensure that the system is properly pressurized after repairs.
     
4. Overheating
   • Causes: Hydraulic systems can overheat if the fluid level is low, the fluid is too thick, or if the cooling system isn't functioning properly. Overheating can cause the system to lose power and may lead to further damage.
     
   • Solution: Check the hydraulic fluid’s temperature and ensure that the cooling system is working efficiently. Replace old or degraded fluid with the correct type and viscosity, and ensure that all cooling components are free of debris.
     

Steps for Changing Hydraulic Fluid on the 70D Excavator
Changing the hydraulic fluid in your 70D excavator is a straightforward process that can prevent many common issues like sluggish operation and overheating. Here’s a step-by-step guide to change the hydraulic fluid:

1. Prepare the Equipment
   • Park the excavator on a level surface, ensuring that the machine is stable.
     
   • Turn off the engine and allow it to cool down before starting the procedure.
     
   • Gather the necessary tools and equipment, including a drain pan, new hydraulic fluid, and safety gloves.
     
2. Drain the Old Hydraulic Fluid
   • Locate the drain plug for the hydraulic system. This is typically found at the bottom of the hydraulic reservoir.
     
   • Place the drain pan underneath the plug to catch the fluid.
     
   • Unscrew the drain plug and allow the fluid to fully drain out. Be careful as the fluid may be hot.
     
3. Inspect the System
   • While the fluid is draining, inspect the hydraulic system for any signs of damage or leaks. Check hoses, pumps, and seals for wear and tear.
     
   • Clean the area around the drain plug and other components to prevent dirt and debris from entering the system.
     
4. Refill the Hydraulic System
   • Once the system is drained, replace the drain plug securely.
     
   • Use the recommended hydraulic fluid for your 70D excavator. Make sure to fill the system slowly and check the fluid level regularly to avoid overfilling.
     
   • After filling, start the machine and allow the hydraulic system to operate for a few minutes, checking for leaks and proper fluid circulation.
     
5. Check the Hydraulic Filters
   • As part of the fluid change, inspect and replace the hydraulic filters if necessary. Clean filters help prevent dirt and contaminants from entering the system, which can lead to damage over time.
     

Preventative Measures to Avoid Hydraulic System Issues
To keep your 70D's hydraulic system in top condition, consider these preventive measures:

1. Regular Fluid Checks: Regularly check the fluid levels and quality. Low or contaminated fluid is a common cause of hydraulic issues, so it’s essential to keep the fluid clean and at the right level.
   
2. Use High-Quality Hydraulic Fluid: Always use the manufacturer-recommended hydraulic fluid to ensure that the system runs smoothly. Poor-quality fluid can cause damage to pumps and seals.
   
3. Proper Storage: When not in use, ensure the excavator is stored in a clean, dry environment. This will help prevent contaminants from entering the hydraulic system and causing damage.
   
4. Routine System Inspection: Perform regular visual inspections of hoses, cylinders, pumps, and filters to detect any signs of wear. Catching small issues early can prevent major repairs down the road.
   

Conclusion
The hydraulic system of your 70D excavator is critical to its performance, and maintaining it properly will ensure that your machine operates efficiently for years. By performing regular maintenance, addressing issues like fluid leaks and low pressure promptly, and following the proper steps for fluid replacement, you can extend the lifespan of your hydraulic system and avoid costly repairs. Always ensure that you’re using high-quality components and fluids to maintain optimal functionality. With a little care and attention, your 70D excavator will continue to provide reliable service on any job site.