CAT 953 Track Loader Steering and Drive System Troubleshooting

[MikePhua]

The 953 and Caterpillar’s Track Loader Legacy
The Caterpillar 953 track loader was introduced in the early 1980s as part of CAT’s push to modernize its crawler loader lineup. Combining the versatility of a wheel loader with the traction of a dozer, the 953 quickly became a favorite in demolition, site prep, and landfill operations. With an operating weight around 30,000 lbs and a bucket capacity of 2.5 to 3.0 cubic yards, it offered a powerful hydrostatic drive system and a fully enclosed cab—features that set it apart from earlier mechanical-drive models.
Caterpillar, founded in 1925, has long been a leader in earthmoving equipment. The 953 was built in Illinois and sold globally, with strong adoption in North America, Europe, and Asia. Its hydrostatic transmission and electronically controlled steering made it a reliable workhorse, but like any machine, it’s not immune to track-related issues.
Understanding the Hydrostatic Drive and Steering System
The 953 uses a dual-path hydrostatic transmission, meaning each track is powered by its own hydraulic motor. Steering is achieved by varying the speed and direction of each motor independently. Key components include:

• Variable displacement hydraulic pumps
  
• Final drive motors with planetary reduction
  
• Electronic control module (ECM) for steering input
  
• Joystick or pedal controls depending on configuration
  
• Brake system for emergency stop and parking
  

When one track fails to respond or behaves erratically, the issue can stem from hydraulic imbalance, electrical faults, or mechanical wear in the final drive.
Common Track Problems and Diagnostic Pathways
Operators may encounter several symptoms when the 953 experiences track issues:

• One track fails to move or moves slower than the other
  
• Machine turns unintentionally or resists steering input
  
• Grinding or whining noise from final drive
  
• Hydraulic fluid overheating or pressure drop
  
• ECM fault codes related to steering or drive response
  

Typical causes include:

• Hydraulic Motor Wear
  • Internal leakage reduces torque output
    
  • Caused by worn seals, bearings, or rotor scoring
    
• Pump Displacement Imbalance
  • One pump fails to adjust properly under load
    
  • May result from faulty swash plate actuator or control valve
    
• Electrical Control Faults
  • ECM misinterprets joystick input
    
  • Wiring harness damage or sensor failure
    
• Final Drive Contamination
  

• Water or debris in gear housing
  
• Leads to bearing failure and gear misalignment
  

A technician in Alberta diagnosed a 953 with right track hesitation. After pressure testing the hydraulic circuit, he found the right motor was leaking internally. Replacing the motor restored full steering response and eliminated the noise.
Inspection and Repair Strategy
To isolate and resolve track problems:

• Check hydraulic fluid level and condition
  
• Inspect hoses and fittings for leaks or abrasion
  
• Use diagnostic software to read ECM fault codes
  
• Perform pressure and flow tests on each drive motor
  
• Remove final drive cover and inspect gears and bearings
  
• Test joystick or pedal input voltage and response curve
  

Recommended hydraulic pressure for the 953’s drive system is typically 5,000–6,000 PSI under load. Flow rates should be balanced within 5% between left and right circuits.
A restorer in Chile rebuilt his 953’s left final drive using aftermarket bearings and a remanufactured motor. After flushing the system and recalibrating the ECM, the loader tracked straight and responded smoothly to steering input.
Preventive Maintenance and Long-Term Reliability
To prevent future track issues:

• Change hydraulic fluid every 1,000 hours or annually
  
• Replace filters and inspect suction screens quarterly
  
• Grease track adjusters and inspect recoil springs monthly
  
• Monitor track tension and adjust to spec (typically 1–1.5 inches sag)
  
• Inspect final drive seals and drain plugs for contamination
  
• Document service intervals and component replacements
  

A fleet manager in Texas added hydrostatic pressure checks to his semi-annual inspection protocol and reduced drive complaints by 70% across his tracked loader fleet.
Conclusion and Recommendations
Track problems in the CAT 953 often stem from hydraulic imbalance, motor wear, or control system faults. With methodical diagnostics and targeted repairs, the machine can be restored to full performance and steering precision.
Recommendations include:

• Pressure test both drive circuits and compare flow rates
  
• Inspect final drives for contamination and gear wear
  
• Replace worn hydraulic motors with matched units
  
• Calibrate ECM and verify control input accuracy
  
• Maintain clean fluid and document service history
  

With proper care and attention to hydraulic health, the 953 continues to push, lift, and maneuver with the power and precision that define Caterpillar’s legacy in tracked equipment.