Caterpillar 951C Crawler Loader Overview

[MikePhua]

Historical Context
The Caterpillar 951C succeeded the 951B during the early 1970s, carrying forward many of its predecessor’s strengths while introducing upgrades. The 951/C series were part of Caterpillar’s line of crawler loaders—machines combining features of bulldozers and loaders, meant for digging, pushing, and loading tasks. Over the production period, from about 1970 to the early 1980s depending on region, more than 17,000 units of the 951B/951C were built globally.
The American, Japanese, and French plants all contributed to the 951C production. The “C” variant brought improvements like sealed loader linkages, hydraulic track adjusters, incremental power increases, and some safety features like rollover protection systems (ROPS).

Key Specifications
Below are typical specifications of a Caterpillar 951C in standard configuration. Actual values may vary by serial number, attachments, or country.

• Engine: 4-cylinder diesel (Cat 3304 on many units)
  
• Net Power Output: ~95 horsepower (~71 kilowatts) at rated engine speed
  
• Operating Weight: ~27,200-28,100 pounds (~12,300-12,800 kg) depending on options
  
• Dimensions:
  • Length with bucket on ground: ~15 ft 7 in (~4.75 m)
    
  • Width over tracks: ~6 ft 5 in (~1.95 m)
    
  • Height to cab top: ~9 ft 4-10 ft depending on configuration (~2.8-3.0 m)
    
• Hydraulic System Flow: ~33 gallons per minute (~125 litres/min)
  
• Ground Contact / Undercarriage: Track gauge ~60 in (152-153 cm) on many units, track shoe width ~14 in, number of track rollers and shoes per side typical of this class
  

Upgrades from 951B to 951C
Some of the main enhancements brought in with the “C” model include:

• Increased power in certain serials (from ~85 hp to ~95 hp) to better handle heavier loads.
  
• Sealed loader linkage to reduce wear and exposure of pivot points to mud, dust, moisture.
  
• Hydraulic track adjusters for easier undercarriage maintenance.
  
• Addition of ROPS in later units for operator safety.
  

Common Issues & Repair Notes
From owner reports and classic-equipment discussions, a few recurring problems and care points:

• Pivot shaft or pivot seal leaks: Leaking seals around steering or drive systems sometimes allow fluid crossover between systems, leading to degraded performance or contamination. Repairing usually involves replacing the pivot seal, re-sealing components, and ensuring fluid reservoirs are correctly isolated.
  
• Track tensioning: Uneven track tension or slack tracks are common. These can often be adjusted via built-in adjusters; sometimes links need removal or the alignment needs checking. Ensuring good tension is critical to avoid derailment or excessive wear.
  
• Parts availability: Many parts are aged; seals, bearings, electrical wiring, alternators (if converted), and undercarriage components may need refurbishment or sourcing from specialty suppliers. Matching serial prefixes and years helps identify correct parts.
  

Value and Economics
For someone considering acquiring a 951C:

• Because of their age, prices tend to vary widely based on condition. Units running well may cost several thousands of dollars; those needing major repair less. A reported asking price under USD 7,000 for machines with leaks or worn tracks was seen, though significant repair work may be required.
  
• Transport, undercarriage work, engine overhaul, seal replacements, and hydraulics are common cost areas. Budgeting for parts and labor is essential.
  

Conclusion
The Caterpillar 951C is a capable crawler loader with solid performance for its era: decent horsepower, sturdy undercarriage, and useful loader capabilities. Its upgrades from the earlier B model make it more reliable in rough or dirty conditions, though age and wear take their toll. For vintage machinery enthusiasts, contractors, or farms seeking a cheap but usable machine, the 951C delivers value—provided one understands its quirks, pays attention to maintenance, and invests in sealing, undercarriage care, and correct hydraulics.