Liebherr R900B Excavator Pedal Functions and Cab Control Layout

[MikePhua]

The R900B and Liebherr’s Excavator Legacy
The Liebherr R900B is part of the company’s long-standing line of hydraulic excavators, developed for mid-size earthmoving, demolition, and utility work. Liebherr, founded in Germany in 1949, became a global leader in construction machinery by emphasizing modular design, operator comfort, and hydraulic precision. The R900B, produced during the late 1990s and early 2000s, was built with a focus on reliability and serviceability, often powered by a Liebherr D924 diesel engine delivering around 150 horsepower.
With an operating weight of approximately 20 metric tons and a dig depth exceeding 6 meters, the R900B was widely used in European infrastructure projects and exported to markets across Asia and North America. Its cab layout reflects the design philosophy of the era—mechanical simplicity paired with hydraulic responsiveness.
Pedal Configuration and Functional Overview
Inside the cab of the R900B, operators typically encounter three primary foot pedals:

• Left travel pedal
  
• Right travel pedal
  
• Swing brake or auxiliary function pedal (varies by configuration)
  

These pedals are mounted on the cab floor and work in conjunction with dual joystick controls. Their functions are as follows:

• Travel pedals: Control forward and reverse movement of the tracks. Pressing the left pedal moves the left track forward; pressing the right pedal moves the right track. Simultaneous pressure propels the machine straight ahead or backward.
  
• Swing brake pedal: Engages or releases the upper carriage swing brake. In some configurations, this pedal may be repurposed for auxiliary hydraulic functions such as hammer activation or shear control.
  

Terminology Note: “Swing brake” refers to a mechanical or hydraulic system that locks the upper structure to prevent rotation. “Auxiliary hydraulics” are additional circuits used to power attachments beyond the standard boom, stick, and bucket.
In 2022, a demolition crew in Lyon retrofitted their R900B with a foot-activated hydraulic hammer control. The original swing brake pedal was rewired to trigger the auxiliary valve, allowing the operator to keep both hands on the joysticks during hammering.
Variations in Pedal Function by Market and Retrofit
Depending on region and factory options, the third pedal may serve different roles:

• In standard European models, it often controls the swing brake
  
• In North American units, it may be wired for auxiliary hydraulic flow
  
• In forestry or demolition packages, it may activate a thumb or tilt rotator
  
• In older machines, it may be unused or disconnected
  

To identify pedal function:

• Trace hydraulic or electrical lines from the pedal to the valve block
  
• Consult the machine’s wiring diagram or hydraulic schematic
  
• Test pedal response with engine running and safety lock disengaged
  
• Check for labeling or embossed symbols near the pedal base
  

A technician in British Columbia discovered that a third pedal in an R900B was connected to a solenoid controlling a high-flow circuit. After testing, it was confirmed to activate a stump shear mounted on the stick.
Maintenance and Troubleshooting Tips
Pedal systems in the R900B are mechanical or electrohydraulic, depending on configuration. Common issues include:

• Stiff pedal movement due to dirt or corrosion
  
• Electrical faults in pedal switches or connectors
  
• Hydraulic leakage from pedal-actuated valves
  
• Misidentification of pedal function after retrofit or repair
  

Solutions:

• Clean pedal pivots and apply lithium grease
  
• Inspect wiring harnesses for wear or rodent damage
  
• Replace pedal switches with OEM-rated components
  
• Label all pedal functions clearly for future operators
  
• Use multimeter to test switch continuity and voltage
  

In 2023, a fleet manager in Poland added color-coded pedal caps to his R900B fleet to prevent operator confusion. Red indicated travel, blue for swing brake, and yellow for auxiliary.
Operator Ergonomics and Control Strategy
The R900B’s pedal layout supports intuitive control when paired with joystick operation. Best practices include:

• Use travel pedals for fine maneuvering in tight spaces
  
• Engage swing brake during lifting or precise placement
  
• Activate auxiliary functions only when attachment is fully visible
  
• Keep pedals clean and unobstructed to prevent accidental activation
  

Some operators retrofit footrests or pedal guards to reduce fatigue during long shifts. Others install cab cameras to monitor attachment response when using foot-actuated tools.
Conclusion
Pedal identification in the Liebherr R900B excavator is essential for safe and efficient operation, especially as machines age or undergo retrofit. Whether controlling travel, swing brake, or auxiliary hydraulics, each pedal plays a role in the operator’s workflow. With proper labeling, maintenance, and understanding of hydraulic and electrical systems, even legacy machines like the R900B can deliver precision and productivity. In the cab of a Liebherr, every pedal is a gateway to control—and knowing what lies beneath your foot is the first step to mastering the machine.