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Caterpillar 955L Historical Background
The Caterpillar 955L was introduced in the mid-1960s as part of the evolution of CAT’s track loader series, succeeding the 955H and preceding the 955K. With a serial prefix of 71J, the 955L was built for heavier-duty applications, boasting an operating weight of approximately 37,000 lbs and powered by the CAT 3304 four-cylinder diesel engine. This naturally aspirated engine produced around 100 horsepower, driving a torque converter transmission and a hydraulically controlled loader system. The 955L was widely used in land clearing, construction, and agricultural work, and thousands were sold globally during its production run.
Symptoms of Power Loss and Delayed Movement
A common issue reported with aging 955L units is sluggish movement and reduced power, especially when cold. In one case, the machine would only move forward or reverse after warming up, and even then, lacked its original strength. This behavior is often linked to low transmission fluid, internal leakage, or worn clutch packs. The torque converter system relies on hydraulic pressure to engage drive gears, and insufficient fluid or degraded seals can cause delayed engagement and weak propulsion.
Transmission Fluid and Suction Screen Maintenance
The 955L’s transmission system includes a suction screen located inside the transmission housing, which filters debris before fluid reaches the pump. Over time, this screen can clog with sediment, reducing flow and causing symptoms similar to low fluid. Regular inspection and cleaning of the suction screen are essential, especially if the machine has sat idle for extended periods.
Recommended service steps:
Model Identification and Decal Confusion
It’s not uncommon for older machines to carry incorrect decals due to repainting or mislabeling. While the unit in question bore a “955L” decal, its serial number (71J5820) confirmed it was a legitimate L-series. Earlier models like the 955H or 955K differ significantly in weight, engine configuration, and hydraulic layout. Accurate identification is crucial for sourcing parts and service manuals.
Fuel System and Filter Blockage
Another potential cause of poor performance is fuel starvation. The 955L uses a mechanical injection pump fed by a lift pump and primary filter. Contaminated fuel or clogged filters can mimic transmission issues by causing engine hesitation and reduced torque. Operators should:
Manual Acquisition and Learning Curve
For new owners unfamiliar with heavy equipment, acquiring a repair manual is essential. The Caterpillar service manual for the 955L includes hydraulic schematics, transmission diagrams, and troubleshooting procedures. While dealer copies are expensive (often over $300), aftermarket reprints are available from suppliers like Jensales or online marketplaces.
Key manuals to obtain:
In one restoration story, the new owner used the 955L to clear overgrown fence rows and remove brush from a neglected farm. Despite limited experience, the machine performed well after basic fluid maintenance. The loader’s mechanical simplicity and robust frame made it forgiving for beginners, though proper training and safety awareness are always recommended.
Conclusion
The Caterpillar 955L remains a powerful and serviceable track loader, even decades after its release. Common issues like delayed movement and power loss are often tied to fluid levels, suction screen blockage, or fuel system faults. With proper identification, maintenance, and documentation, the 955L can be restored to reliable operation—ready to tackle land clearing, grading, or farm revival projects. Its legacy as a durable workhorse continues to earn respect among operators and collectors alike.
The Caterpillar 955L was introduced in the mid-1960s as part of the evolution of CAT’s track loader series, succeeding the 955H and preceding the 955K. With a serial prefix of 71J, the 955L was built for heavier-duty applications, boasting an operating weight of approximately 37,000 lbs and powered by the CAT 3304 four-cylinder diesel engine. This naturally aspirated engine produced around 100 horsepower, driving a torque converter transmission and a hydraulically controlled loader system. The 955L was widely used in land clearing, construction, and agricultural work, and thousands were sold globally during its production run.
Symptoms of Power Loss and Delayed Movement
A common issue reported with aging 955L units is sluggish movement and reduced power, especially when cold. In one case, the machine would only move forward or reverse after warming up, and even then, lacked its original strength. This behavior is often linked to low transmission fluid, internal leakage, or worn clutch packs. The torque converter system relies on hydraulic pressure to engage drive gears, and insufficient fluid or degraded seals can cause delayed engagement and weak propulsion.
Transmission Fluid and Suction Screen Maintenance
The 955L’s transmission system includes a suction screen located inside the transmission housing, which filters debris before fluid reaches the pump. Over time, this screen can clog with sediment, reducing flow and causing symptoms similar to low fluid. Regular inspection and cleaning of the suction screen are essential, especially if the machine has sat idle for extended periods.
Recommended service steps:
- Drain transmission fluid completely
- Remove and clean suction screen
- Refill with OEM-spec transmission oil
- Check for leaks at hoses and fittings
Model Identification and Decal Confusion
It’s not uncommon for older machines to carry incorrect decals due to repainting or mislabeling. While the unit in question bore a “955L” decal, its serial number (71J5820) confirmed it was a legitimate L-series. Earlier models like the 955H or 955K differ significantly in weight, engine configuration, and hydraulic layout. Accurate identification is crucial for sourcing parts and service manuals.
Fuel System and Filter Blockage
Another potential cause of poor performance is fuel starvation. The 955L uses a mechanical injection pump fed by a lift pump and primary filter. Contaminated fuel or clogged filters can mimic transmission issues by causing engine hesitation and reduced torque. Operators should:
- Replace fuel filters regularly
- Inspect fuel lines for air leaks
- Drain water separators if equipped
- Use clean diesel, especially after long storage
Manual Acquisition and Learning Curve
For new owners unfamiliar with heavy equipment, acquiring a repair manual is essential. The Caterpillar service manual for the 955L includes hydraulic schematics, transmission diagrams, and troubleshooting procedures. While dealer copies are expensive (often over $300), aftermarket reprints are available from suppliers like Jensales or online marketplaces.
Key manuals to obtain:
- Service manual (includes teardown procedures)
- Operator’s manual (daily checks and controls)
- Parts manual (exploded diagrams and part numbers)
In one restoration story, the new owner used the 955L to clear overgrown fence rows and remove brush from a neglected farm. Despite limited experience, the machine performed well after basic fluid maintenance. The loader’s mechanical simplicity and robust frame made it forgiving for beginners, though proper training and safety awareness are always recommended.
Conclusion
The Caterpillar 955L remains a powerful and serviceable track loader, even decades after its release. Common issues like delayed movement and power loss are often tied to fluid levels, suction screen blockage, or fuel system faults. With proper identification, maintenance, and documentation, the 955L can be restored to reliable operation—ready to tackle land clearing, grading, or farm revival projects. Its legacy as a durable workhorse continues to earn respect among operators and collectors alike.
