Skid Steer Drive Motor Repairs and Chain System Insights

[MikePhua]

The Rise of Chain-Driven Skid Steers in Compact Equipment
Skid steer loaders have become indispensable in construction, landscaping, agriculture, and demolition. Their compact size, maneuverability, and attachment versatility make them ideal for tight spaces and multi-tasking. Early skid steers, pioneered by Bobcat in the 1960s, used chain-driven systems to transfer power from hydraulic motors to the wheels. This design remains common in many models today, especially in mid-range machines under 75 horsepower.
Chain drives offer simplicity, cost-effectiveness, and ease of service. Unlike planetary final drives or direct shaft systems, chain drives allow for independent wheel movement and are relatively forgiving under load. However, they require regular inspection and maintenance to prevent failure and uneven wear.
Terminology Notes

• Drive Motor: A hydraulic motor that powers the wheels or tracks of a skid steer.
  
• Drive Chain: A roller chain that transmits torque from the motor sprocket to the axle sprocket.
  
• Chain Case: An enclosed compartment housing the drive chains, typically filled with oil for lubrication.
  
• Sprocket: A toothed wheel that engages with the chain to transmit motion.
  

Common Symptoms of Drive Motor and Chain Issues
Operators may encounter several warning signs when a drive motor or chain system begins to fail:

• Loss of drive power on one side
  
• Jerky or uneven movement during turns
  
• Grinding or clunking noises from the chain case
  
• Oil leaks around motor seals or chain case covers
  
• Excessive chain slack or visible wear on sprockets
  

In one case, a contractor in Minnesota noticed his skid steer veering to one side under load. After inspection, he found a broken drive chain and a leaking motor seal. Replacing the chain and resealing the motor restored full functionality.
Disassembly and Inspection Strategy
Repairing a drive motor or chain system requires careful disassembly and documentation. Key steps include:

• Drain chain case oil and inspect for metal shavings or discoloration
  
• Remove motor mounting bolts and disconnect hydraulic lines
  
• Inspect motor shaft for scoring, pitting, or seal damage
  
• Check sprocket teeth for rounding or uneven wear
  
• Measure chain stretch using a caliper or chain gauge
  
• Replace chains in matched pairs to ensure even tension
  

Technicians recommend using OEM parts or high-quality aftermarket components. Replacing only one chain or sprocket can lead to premature failure due to imbalance.
Chain Tension and Lubrication Best Practices
Proper chain tension is critical for performance and longevity. Chains should have minimal slack—typically 1/2" to 3/4" of vertical movement when pressed. Over-tightening can cause binding and accelerated wear, while loose chains may skip or derail.
Lubrication is equally important. Chain cases should be filled with gear oil or chain case fluid as specified by the manufacturer. Common grades include SAE 80W-90 or proprietary blends. Oil should be changed every 500 hours or annually, whichever comes first.
A technician in Alberta shared how his chain case oil turned milky due to water intrusion. After flushing the case and replacing the seals, he switched to synthetic oil with better moisture resistance.
Drive Motor Rebuild vs Replacement
Hydraulic drive motors can be rebuilt if the housing and shaft are intact. Rebuild kits typically include:

• Shaft seals
  
• Bearings
  
• O-rings
  
• Valve plates
  

However, if the motor has internal scoring, cracked housing, or excessive shaft play, replacement is recommended. Rebuilt motors may cost $500–$800, while new units range from $1,200 to $2,500 depending on brand and displacement.
Some operators opt for remanufactured motors with warranty coverage. These units are factory-tested and often include upgraded seals and coatings for extended life.
Preventive Maintenance and Long-Term Reliability
To extend the life of drive motors and chains:

• Inspect chain tension monthly
  
• Change chain case oil annually
  
• Clean breather vents to prevent pressure buildup
  
• Monitor hydraulic fluid for contamination
  
• Avoid sudden directional changes under full load
  
• Keep sprockets aligned and torque bolts to spec
  

Fleet managers often track maintenance intervals using hour meters and service logs. One rental company in Texas reduced chain failures by 40% after implementing a quarterly inspection program.
Conclusion
Skid steer drive motor and chain systems are robust but require attention to detail. By understanding the mechanics of chain tension, lubrication, and motor wear, operators can prevent costly downtime and maintain peak performance. Whether rebuilding a motor or replacing a worn chain, a methodical approach ensures safe and reliable operation—keeping these compact powerhouses moving through every jobsite challenge.