Poclain RC 200 Fast Travel System and Hydraulic Drive Behavior

[MikePhua]

The Poclain RC 200 and Its Engineering Legacy
The Poclain RC 200 hydraulic excavator was part of a pioneering generation of fully hydraulic machines developed in France during the 1970s and 1980s. Poclain, founded in 1927, revolutionized the excavator industry by introducing hydrostatic drive systems and swing circuits long before they became standard. The RC 200 was a mid-size crawler excavator, typically weighing around 20 metric tons, designed for general excavation, trenching, and light demolition.
Unlike many of its contemporaries, the RC 200 featured a hydrostatic travel system with dual-speed capability, allowing operators to switch between digging mode and fast travel. This made it especially useful for large sites where repositioning the machine quickly was essential. Though Poclain was eventually absorbed into Case in the late 1980s, many RC-series machines remain in use today, especially in Europe and North Africa.
Fast Travel System Function and Control
The fast travel feature on the RC 200 is hydraulically actuated and typically controlled via a foot pedal or dash-mounted switch. When engaged, the system redirects hydraulic flow to increase track motor speed while reducing torque. This is ideal for moving across a jobsite but not suitable for climbing or pushing.
Key components include:

• Travel motors with dual-speed capability
  
• Hydraulic selector valve or solenoid
  
• Pilot control circuit for mode switching
  
• Pressure relief valve to protect against overload
  
• Return line filter and suction strainer
  

Terminology notes:

• Hydrostatic drive: A propulsion system using hydraulic motors powered by variable-displacement pumps.
  
• Pilot control: A low-pressure hydraulic signal used to actuate valves or control functions.
  

In Ontario, a contractor used an RC 200 to clear a large drainage field. The fast travel mode allowed him to reposition the machine quickly between trench lines, saving hours of idle time.
Common Issues Affecting Fast Travel Performance
Operators may encounter the following problems:

• Machine fails to switch into fast travel mode
  
• Travel speed remains slow despite mode activation
  
• Jerky or uneven movement during travel
  
• Audible hydraulic whine or pressure drop
  
• Fast travel only works intermittently or under light load
  

Likely causes include:

• Faulty selector valve or solenoid not shifting properly
  
• Pilot pressure loss due to cracked hose or blocked orifice
  
• Contaminated hydraulic fluid affecting valve response
  
• Worn travel motor seals or internal leakage
  
• Electrical fault in switch or relay (if electronically actuated)
  

Diagnostic steps:

• Check pilot pressure at selector valve (should exceed 300 psi)
  
• Inspect solenoid wiring and connector integrity
  
• Test travel motor case drain flow for signs of internal leakage
  
• Sample hydraulic fluid for contamination or water content
  
• Verify selector valve spool movement and spring tension
  

In Chile, a mining crew diagnosed a fast travel failure caused by a blocked pilot line. After cleaning the orifice and replacing the hose, the system returned to full function.
Hydraulic System Maintenance and Fluid Integrity
The RC 200’s hydraulic system is robust but sensitive to fluid quality and filter condition. Preventive measures include:

• Replace hydraulic fluid every 1,000 hours or annually
  
• Change return and suction filters every 500 hours
  
• Use ISO 46 hydraulic oil with anti-wear additives
  
• Monitor fluid temperature during operation (should remain below 85°C)
  
• Inspect hoses and fittings quarterly for leaks or abrasion
  

Suggested upgrades:

• Install magnetic trap in return line to catch fine metal particles
  
• Add pilot pressure gauge to cab for real-time diagnostics
  
• Use synthetic fluid in cold climates for better flow
  
• Retrofit selector valve with manual override for emergency use
  

In South Africa, a vineyard crew added a pilot pressure gauge to their RC 200. This helped them catch a pressure drop caused by a cracked fitting near the control valve.
Travel Motor Behavior and Load Sensitivity
Fast travel relies on the travel motors operating at high displacement. Common issues include:

• Internal wear reducing volumetric efficiency
  
• Case drain flow exceeding spec due to seal leakage
  
• Motor overheating during extended travel
  
• Pressure drop under load due to relief valve misadjustment
  
• Uneven speed between left and right tracks
  

Maintenance tips:

• Inspect motor case drain flow monthly
  
• Replace seals and bearings every 3,000 hours
  
• Clean motor housing and check for debris buildup
  
• Test relief valve pressure and adjust to factory spec
  
• Log travel speed and motor temperature trends
  

In Tennessee, a grading crew rebuilt their travel motors after noticing uneven speed and overheating. The new seals and bearings restored balance and improved fuel efficiency.
Preventive Maintenance and Long-Term Reliability
To keep the fast travel system functional:

• Inspect selector valve and pilot lines monthly
  
• Replace hydraulic fluid and filters on schedule
  
• Clean travel motor case drain filters annually
  
• Log travel performance and pressure readings
  
• Train operators to avoid fast travel under heavy load or incline
  

Suggested spares to stock:

• Selector valve seal kits
  
• Pilot line fittings and clamps
  
• Travel motor seal sets
  
• Hydraulic filters and O-rings
  
• Solenoid connectors and relays
  

In New Zealand, a contractor added a fast travel check to his pre-shift inspection. This helped catch early signs of valve sticking and prevented mid-job breakdowns.
Operator Stories and Field Wisdom
In Poland, a snow-clearing team used an RC 200 for winter trenching. After noticing sluggish travel, they traced the issue to a pilot line pinched under the cab. Rerouting the line restored full control.
In Alberta, a demolition crew rebuilt their fast travel selector valve using a kit sourced from a retired RC 300. The parts matched, and the machine returned to full responsiveness.
Conclusion
Fast travel on the Poclain RC 200 is a valuable feature that enhances mobility and jobsite efficiency. With proper diagnostics, clean fluid, and attention to pilot pressure and valve behavior, the system can remain reliable even after decades of service. Whether trenching in clay or repositioning across gravel, fast travel keeps the RC 200 moving—and every second saved is a step ahead.