Troubleshooting Steering Issues in the 1985 CAT 920 Loader

[MikePhua]

The Caterpillar 920 is a versatile and durable wheel loader, widely used in construction, agriculture, and other heavy-duty industries. However, like all machines, it can experience mechanical issues over time. One of the most common problems faced by operators of older machines like the 1985 CAT 920 is steering failure or irregular steering behavior. This guide explores potential causes of steering issues in the CAT 920, troubleshooting steps, and preventive measures to keep the loader’s steering system functioning properly.
Understanding the Steering System of the CAT 920
The CAT 920 is equipped with a hydraulic steering system, which relies on hydraulic fluid to power the steering mechanism. Hydraulic systems are commonly used in heavy equipment because of their ability to generate high amounts of force with relatively low input. The key components of the hydraulic steering system include:

1. Steering Gear: The steering gear directs the flow of hydraulic fluid to the steering cylinders, controlling the direction of the wheels.
   
2. Steering Cylinders: These cylinders are responsible for moving the wheels in response to the operator’s input. They are powered by hydraulic fluid, which is pressurized by the pump.
   
3. Hydraulic Pump: The hydraulic pump generates the pressure required to power the steering system. It’s usually driven by the engine and supplies fluid to the steering gear.
   
4. Hydraulic Fluid: The fluid used in the hydraulic system helps transmit force from the pump to the cylinders. Over time, fluid degradation or contamination can lead to performance issues.
   
5. Steering Linkage: The mechanical linkage that connects the steering gear to the wheels. A malfunction in the steering linkage, such as wear or bending, can contribute to steering problems.
   

Common Causes of Steering Issues in the CAT 920

1. Low or Contaminated Hydraulic Fluid: One of the most common reasons for steering problems is insufficient or contaminated hydraulic fluid. If the fluid level is low, the system won’t have enough pressure to move the steering cylinders effectively, resulting in sluggish or unresponsive steering. Contaminants in the fluid, such as dirt or metal shavings, can damage the system components and lead to failure.
   
2. Worn Steering Cylinders or Seals: Over time, the seals within the steering cylinders can wear out, leading to fluid leaks and reduced steering power. Leaking cylinders are one of the most common causes of poor steering performance in the CAT 920.
   
3. Malfunctioning Hydraulic Pump: If the hydraulic pump is failing, it won’t generate enough pressure to operate the steering system properly. Signs of a failing pump include difficulty steering, strange noises, or erratic steering behavior. A pump failure is a serious issue and often requires replacement.
   
4. Faulty Steering Gear: The steering gear is responsible for directing hydraulic fluid to the cylinders. If the gear is damaged or worn, it may fail to distribute fluid correctly, resulting in poor or unpredictable steering control. This can be caused by mechanical wear or fluid contamination.
   
5. Damaged or Misaligned Steering Linkage: If the steering linkage is damaged or misaligned, it may cause uneven steering or difficulty turning the wheels. This can result from general wear, corrosion, or an impact to the vehicle.
   
6. Air in the Hydraulic System: Air trapped in the hydraulic system can cause erratic steering or a complete lack of response. Air bubbles reduce the efficiency of the hydraulic fluid, preventing the steering cylinders from receiving adequate pressure.
   
7. Electrical Issues: In some cases, electrical issues related to steering components (such as electric sensors or controllers) can interfere with the proper functioning of the system.
   

Diagnosing Steering Problems in the CAT 920
Diagnosing steering problems in the CAT 920 requires a systematic approach to pinpoint the root cause. Follow these steps to identify the issue:

1. Check Hydraulic Fluid Levels and Quality: Start by checking the hydraulic fluid level and inspecting its condition. If the fluid is low, top it up and check for any obvious signs of leakage. If the fluid is contaminated or dirty, it should be replaced. If the fluid looks clean and at the correct level, move on to other troubleshooting steps.
   
2. Inspect the Steering Cylinders: Look for any visible leaks around the steering cylinders and their seals. If the seals are worn or damaged, fluid will leak out, reducing the system’s pressure and performance. If the cylinders are leaking, they may need to be re-sealed or replaced.
   
3. Test the Hydraulic Pump: If the fluid level and steering cylinders appear to be in good condition, the next step is to test the hydraulic pump. Start the machine and check for any unusual noises, such as whining or grinding sounds, which may indicate a problem with the pump. Also, check for weak steering response at low or high speeds.
   
4. Examine the Steering Gear: Inspect the steering gear for signs of damage or wear. If the gear is faulty, the fluid may not be directed properly to the cylinders, causing poor steering performance. A malfunctioning steering gear may need to be repaired or replaced.
   
5. Inspect the Steering Linkage: Check for any visible damage or misalignment in the steering linkage. If there are any bent or worn parts, they may need to be replaced or adjusted. Also, check the condition of the bushings and bearings within the linkage.
   
6. Check for Air in the System: If the steering is jerky or unresponsive, air could be trapped in the hydraulic system. To remove air from the system, run the loader with the steering turned fully to the left and right several times. This will allow the air to escape and improve steering performance.
   

Repairing Steering Issues in the CAT 920
Once the problem has been identified, it’s important to follow the correct procedures to fix it:

1. Hydraulic Fluid Replacement: If the fluid is contaminated, drain the old fluid, clean the reservoir, and refill with fresh, clean hydraulic fluid. Be sure to use the fluid recommended by the manufacturer to ensure optimal performance.
   
2. Replacing Steering Cylinders or Seals: If the steering cylinders are leaking, the seals will need to be replaced. In some cases, the entire cylinder may need to be replaced if it’s damaged beyond repair. When replacing seals, ensure that the correct seal kit is used.
   
3. Pump Replacement: If the hydraulic pump is malfunctioning, it may need to be replaced. A professional technician should perform this repair, as replacing the pump involves disassembling parts of the hydraulic system.
   
4. Steering Gear Repair or Replacement: If the steering gear is found to be damaged or malfunctioning, it will need to be repaired or replaced. This process may involve disassembling the steering column and other components.
   
5. Steering Linkage Adjustment: If the steering linkage is damaged or misaligned, it can often be repaired by replacing the affected parts or adjusting the linkage components. Ensure that the alignment is correct to prevent further wear or damage.
   

Preventive Maintenance to Avoid Steering Issues
Preventing steering issues is always preferable to dealing with repairs. Here are some preventive maintenance tips to keep your CAT 920’s steering system functioning smoothly:

1. Regular Fluid Checks: Routinely check the hydraulic fluid level and condition. Keeping the fluid clean and topped up helps prevent many common steering problems, including pump failure and poor cylinder performance.
   
2. Inspect Seals and Cylinders: Regularly check the steering cylinders and seals for wear or leaks. Early detection of seal damage can prevent fluid loss and ensure consistent steering performance.
   
3. Clean and Replace Filters: The hydraulic system relies on clean fluid to operate efficiently. Regularly change the fluid filter and ensure that the system is free of contaminants. A clogged filter can reduce the effectiveness of the hydraulic pump and cause steering issues.
   
4. Lubricate Steering Components: Lubricate the steering linkage and other moving components to reduce wear. Proper lubrication helps prevent corrosion and mechanical failure.
   
5. Monitor for Unusual Noises: Always listen for any unusual noises when operating the machine. Whining, grinding, or knocking sounds can indicate hydraulic issues, such as air in the system or a failing pump.
   

Conclusion
Steering issues in the 1985 CAT 920 loader can be caused by a variety of factors, ranging from low hydraulic fluid to faulty components in the steering system. Diagnosing the issue requires a systematic approach, starting with fluid checks and progressing to inspections of the steering gear, pump, and cylinders. Regular preventive maintenance is key to keeping the steering system functioning properly and preventing costly repairs down the line. By staying proactive and addressing issues early, operators can ensure smooth and efficient operation of their CAT 920 loader for years to come.