Identifying and Understanding Power Steering Pumps on Cummins Engines

[MikePhua]

Power steering pumps play a crucial role in modern heavy equipment, particularly in construction machinery where precision and control are critical. The Cummins 855 engine, commonly used in large machinery, often requires specific maintenance of its power steering pump. However, due to variations in pump types and designs across different models, identifying the correct pump can sometimes be tricky. This article delves into the purpose, types, and troubleshooting tips related to power steering pumps on Cummins 855 engines.
The Role of Power Steering Pumps
Power steering pumps are responsible for providing hydraulic pressure that assists the driver in turning the wheel with ease. Without the power assistance, steering would require a lot more physical effort, especially in large, heavy vehicles like those using the Cummins 855 engine.
In construction machinery, such as loaders, graders, and excavators, the power steering system ensures that the operator can maneuver the vehicle in tight spaces with minimal force. The pump ensures smooth steering by continuously circulating hydraulic fluid to the steering mechanism.
Identifying the Power Steering Pump on a Cummins 855 Engine
The Cummins 855 engine, which is used in various construction machines, has different models and configurations. Each model may use a specific type of power steering pump. Some engines use a gear-driven pump, while others may have a belt-driven one. Identifying the right pump is essential when performing maintenance or repairs to ensure compatibility and avoid damage.
Key Identification Features

• Mounting Type: Pumps can be mounted directly to the engine block or mounted on a frame. Gear-driven pumps are often attached to the engine itself, while belt-driven ones may be driven by the crankshaft via a pulley system.
  
• Pump Design: The two most common designs for power steering pumps are gear pumps and vane pumps. Gear pumps are typically more robust and suited for industrial machinery, while vane pumps are known for their quiet operation and efficiency.
  
• Fluid Type: The power steering system in most equipment uses hydraulic fluid, but the type of fluid may vary based on the machine’s design specifications. Always check the manual to ensure the correct type of fluid is used, as using the wrong fluid can result in pump damage or system malfunction.
  

Where to Find the Pump
The power steering pump is typically located near the front of the engine, attached to the engine block or an auxiliary bracket. It is often driven by the engine through a V-belt or gear assembly. In many cases, it will be situated close to the steering mechanism and will be connected by hoses that circulate hydraulic fluid.
Common Types of Power Steering Pumps in Cummins 855 Engines
The Cummins 855 engine can be found in various heavy-duty vehicles, and these vehicles may use different types of pumps. Below are the most common types found in machinery using the 855 engine:
1. Gear-Driven Power Steering Pumps

• Description: Gear-driven pumps are typically used in more robust machinery where high-pressure hydraulics are needed. They are known for their durability and longevity.
  
• Applications: Often found in large construction equipment like dump trucks, bulldozers, and heavy machinery that requires reliable steering assistance.
  

2. Vane Pumps

• Description: Vane pumps operate using a series of blades or vanes that slide in and out of a rotor. These pumps are typically quieter and more efficient but may not be as durable as gear-driven pumps under heavy loads.
  
• Applications: Common in industrial machinery and smaller equipment where noise reduction and smoothness are desired.
  

3. Belt-Driven Pumps

• Description: A belt-driven pump uses a pulley system connected to the engine’s crankshaft to generate the required hydraulic pressure. This type is more common in vehicles where space constraints do not allow for a gear-driven system.
  
• Applications: Typically used in smaller, compact machines or where ease of maintenance is a priority.
  

4. Electric Steering Pumps

• Description: While not typical for the Cummins 855 engine, electric pumps are becoming more popular due to their energy efficiency. These pumps use an electric motor to generate hydraulic pressure, reducing mechanical load on the engine.
  
• Applications: Found in some modern machinery where reduced engine load is critical.
  

Troubleshooting Power Steering Pump Issues
Power steering pumps, like any component, can fail due to wear and tear, improper maintenance, or system contamination. Below are common symptoms of power steering pump issues and steps to troubleshoot them.
1. Lack of Steering Assist

• Possible Causes: Low fluid levels, worn pump, or air in the system.
  
• Troubleshooting Steps:
  • Check fluid levels and top them off if needed.
    
  • Inspect for leaks in the power steering hoses.
    
  • If the pump is worn out, consider replacing it.
    

2. Pump Noise (Whining or Grinding)

• Possible Causes: Air in the system, low fluid, or a faulty pump.
  
• Troubleshooting Steps:
  • Bleed the power steering system to remove any air.
    
  • Replace the pump if it is grinding.
    
  • If noise persists, inspect the power steering belt for tension and wear.
    

3. Steering Fluid Leaks

• Possible Causes: Cracked hoses, loose connections, or a faulty pump seal.
  
• Troubleshooting Steps:
  • Inspect the power steering pump for leaks.
    
  • Tighten any loose connections.
    
  • Replace hoses or seals as needed.
    

4. Increased Steering Effort

• Possible Causes: A clogged filter, worn-out pump, or low fluid.
  
• Troubleshooting Steps:
  • Replace the power steering filter if clogged.
    
  • Check the pump and replace if necessary.
    
  • Ensure the fluid is topped off and clean.
    

When to Replace a Power Steering Pump
In some cases, troubleshooting may reveal that the power steering pump is beyond repair. If you notice any of the following signs, it may be time for a replacement:

• Persistent noise even after bleeding the system.
  
• Visible damage to the pump or housing.
  
• A drastic drop in steering responsiveness despite adequate fluid levels.
  

When replacing a power steering pump, always ensure that the new pump is compatible with the specific make and model of the Cummins 855 engine. Using the wrong pump can lead to hydraulic issues and operational inefficiencies.
Conclusion
Understanding how to identify, maintain, and troubleshoot power steering pumps is crucial for ensuring the performance and longevity of machinery equipped with Cummins 855 engines. Proper knowledge of the different types of pumps, their symptoms of failure, and maintenance procedures will help operators avoid costly repairs and downtime. Whether you're working with gear-driven, vane, or belt-driven pumps, maintaining the power steering system in optimal condition ensures a smoother, safer operation of your heavy equipment.