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The Legacy of the 955K Track Loader
The Caterpillar 955K is a crawler loader that represents a transitional era in heavy equipment design—bridging the gap between purely mechanical machines and the early adoption of hydraulic sophistication. Introduced in the late 1960s and produced through the 1970s, the 955K was part of Caterpillar’s highly successful 955 series, which began in the 1950s and sold tens of thousands of units globally. Caterpillar Inc., founded in 1925, had already established dominance in the dozer and loader markets, and the 955K reinforced its reputation for building rugged, versatile machines.
The 955K was designed for excavation, loading, and light dozing tasks. It was widely used in construction, demolition, and land clearing, particularly in regions where wheeled loaders struggled with traction. Its compact footprint and high breakout force made it ideal for working in confined spaces or on uneven terrain.
Core Specifications and Mechanical Features
Restoring a 955K today involves a mix of mechanical repair, parts sourcing, and adaptation. Common issues include:
A retired operator in Pennsylvania recalled using a 955K to load coal in the 1980s. He praised its ability to climb spoil piles and push into tight corners where larger machines couldn’t reach. Despite its age, he noted that the machine’s mechanical simplicity made it easy to repair in the field with basic tools.
In another case, a restoration enthusiast in Alberta rebuilt a 955K from a salvage yard find. He fabricated new fenders, replaced the seat and gauges, and sourced a rebuilt 3304 engine from a marine application. The loader now serves on his farm for gravel work and snow removal.
Maintenance Recommendations for Long-Term Use
To keep a 955K running reliably:
The 955K was eventually succeeded by the 955L and later by the 963 series, which introduced hydrostatic drive and more advanced hydraulics. However, the 955K remains a favorite among collectors and small contractors due to its mechanical durability and straightforward design.
Caterpillar’s track loader line has evolved significantly, but the 955K helped define the category. Its success contributed to Caterpillar’s dominance in the loader market and influenced the design of future machines.
Conclusion
The Caterpillar 955K track loader is more than a relic—it’s a symbol of practical engineering and field-tested resilience. Whether used for excavation, loading, or restoration, it continues to prove its worth decades after production ended. For those willing to invest in maintenance and care, the 955K offers a rewarding blend of power, simplicity, and historical significance.
The Caterpillar 955K is a crawler loader that represents a transitional era in heavy equipment design—bridging the gap between purely mechanical machines and the early adoption of hydraulic sophistication. Introduced in the late 1960s and produced through the 1970s, the 955K was part of Caterpillar’s highly successful 955 series, which began in the 1950s and sold tens of thousands of units globally. Caterpillar Inc., founded in 1925, had already established dominance in the dozer and loader markets, and the 955K reinforced its reputation for building rugged, versatile machines.
The 955K was designed for excavation, loading, and light dozing tasks. It was widely used in construction, demolition, and land clearing, particularly in regions where wheeled loaders struggled with traction. Its compact footprint and high breakout force made it ideal for working in confined spaces or on uneven terrain.
Core Specifications and Mechanical Features
- Engine
Powered by the Caterpillar 3304 four-cylinder diesel engine, the 955K delivered approximately 125 gross horsepower. Known for its reliability and torque, the 3304 was used across multiple Cat machines and remains serviceable today.
- Transmission
The 955K featured a powershift transmission with three forward and three reverse speeds. This allowed smooth directional changes under load, a major advantage over earlier clutch-and-brake systems.
- Undercarriage
Equipped with heavy-duty track frames and sealed rollers, the undercarriage was designed for durability in abrasive conditions. Track gauge and shoe width varied by configuration, with wider shoes available for soft ground.
- Bucket and Lift System
The standard bucket capacity was around 1.5 cubic yards, with optional multi-purpose and rock buckets. The lift arms used a Z-bar linkage for high breakout force and fast dump cycles.
- Hydraulics
The 955K used open-center hydraulics with gear-type pumps. While not as efficient as modern load-sensing systems, the setup was simple and easy to maintain.
- Powershift Transmission
A transmission that uses planetary gear sets and hydraulic clutches to shift gears without stopping.
- Z-Bar Linkage
A loader arm configuration that maximizes breakout force and improves bucket rollback angles.
- Track Gauge
The distance between the centerlines of the tracks. Affects stability and turning radius.
- Open-Center Hydraulics
A hydraulic system where fluid flows continuously through the control valves until a function is activated.
Restoring a 955K today involves a mix of mechanical repair, parts sourcing, and adaptation. Common issues include:
- Hydraulic Cylinder Wear
Lift and tilt cylinders often leak due to worn seals. Rebuilding kits are available, but rod scoring may require machining or replacement.
- Transmission Slippage
Powershift units may lose clutch pressure due to worn seals or contaminated fluid. Flushing the system and replacing clutch packs can restore performance.
- Undercarriage Fatigue
Track links, rollers, and sprockets wear unevenly over time. Replacing the entire undercarriage is costly but often necessary for reliable operation.
- Electrical System Degradation
Original wiring harnesses may suffer from corrosion and brittle insulation. Rewiring with modern materials improves reliability and safety.
- Fuel System Contamination
Sediment in the tank and injector wear are common. Cleaning the tank, replacing filters, and rebuilding injectors are standard procedures.
A retired operator in Pennsylvania recalled using a 955K to load coal in the 1980s. He praised its ability to climb spoil piles and push into tight corners where larger machines couldn’t reach. Despite its age, he noted that the machine’s mechanical simplicity made it easy to repair in the field with basic tools.
In another case, a restoration enthusiast in Alberta rebuilt a 955K from a salvage yard find. He fabricated new fenders, replaced the seat and gauges, and sourced a rebuilt 3304 engine from a marine application. The loader now serves on his farm for gravel work and snow removal.
Maintenance Recommendations for Long-Term Use
To keep a 955K running reliably:
- Change engine oil every 250 hours using high-zinc diesel-rated oil
- Replace hydraulic filters and fluid every 500 hours
- Inspect track tension monthly and adjust using the grease cylinder system
- Grease all pivot points daily, especially bucket pins and lift arms
- Monitor transmission fluid for discoloration or metal particles
- Clean radiator fins and check coolant levels regularly
The 955K was eventually succeeded by the 955L and later by the 963 series, which introduced hydrostatic drive and more advanced hydraulics. However, the 955K remains a favorite among collectors and small contractors due to its mechanical durability and straightforward design.
Caterpillar’s track loader line has evolved significantly, but the 955K helped define the category. Its success contributed to Caterpillar’s dominance in the loader market and influenced the design of future machines.
Conclusion
The Caterpillar 955K track loader is more than a relic—it’s a symbol of practical engineering and field-tested resilience. Whether used for excavation, loading, or restoration, it continues to prove its worth decades after production ended. For those willing to invest in maintenance and care, the 955K offers a rewarding blend of power, simplicity, and historical significance.
