Caterpillar 951B

[MikePhua]

Overview of the 951B
The Caterpillar 951B is a classic track loader that became a workhorse in construction and earthmoving during the late 1970s and 1980s. Caterpillar, founded in 1925, has a long-standing reputation for producing reliable heavy machinery. The 951B combines the capabilities of a crawler tractor with a front loader, providing versatility for digging, loading, grading, and material handling. Its robust design allowed it to operate in demanding environments, from quarries to road construction projects.
Engine and Performance

• Engine Type: Caterpillar D343 diesel engine
  
• Gross Power: Approximately 160 hp (119 kW)
  
• Operating Weight: Around 42,000 lbs (19,050 kg)
  
• Fuel Capacity: 80 gallons (303 liters)
  
• Travel Speed: 2.5 mph (4 km/h) in low range, 4 mph (6.4 km/h) in high range
  The D343 engine is known for its durability, providing consistent torque for heavy lifting and pushing. Its mechanical fuel injection system makes it simpler to maintain in the field compared to modern electronically controlled engines.
  

Hydraulic System

• Hydraulic Type: Open-center system with gear pump
  
• Operating Pressure: 2,500 psi (172 bar)
  
• Functions Controlled: Boom lift, bucket tilt, auxiliary hydraulics
  Hydraulics on the 951B are straightforward but reliable, allowing precise control over the loader and attachments. Regular maintenance of hoses, seals, and fluid ensures consistent performance.
  

Undercarriage and Tracks

• Track Type: Steel tracks with grouser pads
  
• Track Length on Ground: 9 ft (2.74 m)
  
• Ground Pressure: 7.8 psi (0.54 bar)
  The steel tracks provide traction on rough terrain and stability while lifting heavy loads. Track tensioning must be checked frequently to prevent accelerated wear on rollers and sprockets.
  

Attachments and Versatility

• Standard Bucket: 3.5 yd³ (2.7 m³) capacity
  
• Optional Forks and Grapples: For material handling and timber work
  
• Dozer Blade Retrofit: Some 951B units were fitted with front blades for dozing operations
  This versatility allowed the 951B to serve multiple roles on job sites, from earthmoving to snow clearing or lumber handling.
  

Maintenance and Common Issues

• Engine: Check for blow-by, fuel leaks, and proper oil levels
  
• Hydraulics: Inspect hoses for cracks and seals for leaks; replace filters every 250 hours
  
• Tracks and Undercarriage: Inspect sprockets, rollers, and pins regularly; adjust track tension
  
• Electrical: Older models may have worn wiring, which should be inspected for shorts or corrosion
  Owners have reported that keeping up with preventative maintenance extends the operational life of the 951B to over 20,000 hours in many cases.
  

Technical Terms Explained

• Blow-by: Combustion gases escaping past piston rings into the crankcase, indicating wear
  
• Grouser Pad: Raised segments on a track shoe to increase traction on soft or uneven terrain
  
• Open-Center Hydraulic System: A hydraulic system where fluid flows continuously back to the tank when controls are not engaged
  
• Torque Converter: Transfers engine power to the transmission smoothly, allowing heavy loads to move without stalling
  

Tips for Buying Used 951B

• Inspect Engine Compression: Low compression can indicate worn cylinders or rings
  
• Check Hydraulics: Look for smooth operation of boom and bucket without jerking or leaks
  
• Examine Undercarriage Wear: Excessive wear on sprockets or rollers may require expensive replacement
  
• Test Travel Function: Both forward and reverse should be smooth and responsive
  
• Verify Service History: Machines with documented maintenance generally have longer remaining life
  

Conclusion
The Caterpillar 951B remains a respected machine for collectors and operators who appreciate its simplicity and durability. Its combination of power, hydraulic control, and track performance makes it a versatile choice for heavy-duty applications. Proper maintenance, attention to hydraulic and track systems, and careful inspection before purchase ensure continued reliability and operational efficiency. The 951B stands as an enduring example of Caterpillar’s commitment to practical, long-lasting construction equipment.