Fiat-Allis 645B Is a Forgotten Loader with Lasting Muscle

[MikePhua]

The Origins of Fiat-Allis and the 645B Lineage
Fiat-Allis was born from a 1974 merger between Italy’s Fiat and America’s Allis-Chalmers, combining European design sensibilities with rugged Midwestern engineering. The company focused on earthmoving equipment, and the 645B wheel loader emerged in the late 1970s as a mid-size workhorse for construction, quarrying, and municipal use. Though production ceased decades ago, the 645B remains in service across North America, a testament to its mechanical simplicity and brute strength.
The 645B was part of a broader push by Fiat-Allis to compete with Caterpillar, John Deere, and Case in the wheel loader market. While it never achieved the sales volume of its rivals, it carved out a niche among operators who valued straightforward mechanics and a no-frills approach to productivity.
Core Specifications and Performance Profile
The Fiat-Allis 645B is powered by a turbocharged Cummins diesel engine, typically the NH220 or 6CTA series, delivering around 160–180 horsepower. It features a powershift transmission, four-wheel drive, and a Z-bar loader linkage for high breakout force.
Key specs include:

• Operating weight: ~28,000 lbs
  
• Bucket capacity: 3.0–3.5 cubic yards
  
• Breakout force: ~28,000 lbs
  
• Top speed: ~25 mph
  
• Hydraulic system pressure: ~2,500 psi
  

Terminology note:

• Z-bar linkage: A loader arm configuration that maximizes breakout force and dump clearance, ideal for digging and material handling.
  
• Breakout force: The maximum force the bucket can exert to dislodge material from a pile.
  

Operators often praise the 645B’s torque and traction, especially in muddy or uneven terrain. Its mechanical drivetrain and limited electronics make it easier to repair in the field, a major advantage in remote or budget-constrained operations.
Common Issues and Maintenance Insights
Despite its durability, the 645B has a few recurring issues that owners should monitor:

• Transmission hesitation: Powershift units may slip or delay engagement if fluid is old or filters are clogged.
  
• Hydraulic leaks: Aging hoses and cylinder seals often drip under pressure, especially in cold weather.
  
• Electrical corrosion: The wiring harness and starter solenoid are vulnerable to moisture and rust.
  
• Brake fade: The air-over-hydraulic brake system can lose pressure if not maintained, especially in older units.
  

Recommendations:

• Replace transmission fluid and filters every 500 hours
  
• Inspect hydraulic hoses quarterly and replace any with surface cracking
  
• Use dielectric grease on all electrical connectors
  
• Test brake pressure monthly and bleed the system annually
  

One operator in Montana shared that his 645B had over 12,000 hours and still ran daily in a gravel pit. He rebuilt the transmission once and replaced the loader pins twice but never touched the engine—proof of the Cummins block’s longevity.
Parts Availability and Cross-Compatibility
Fiat-Allis ceased operations in the early 1990s, and parts support became fragmented. However, many components are still available through aftermarket suppliers, salvage yards, and cross-compatibility with other brands.
Common interchangeable parts:

• Engine components (shared with other Cummins-powered machines)
  
• Hydraulic cylinders (can be rebuilt or replaced with generic units)
  
• Loader pins and bushings (standard sizes available)
  
• Electrical switches and gauges (can be retrofitted)
  

Tips for sourcing parts:

• Keep a detailed parts book and serial number record
  
• Join regional equipment forums or owner groups for leads
  
• Use industrial supply catalogs for hoses, seals, and fittings
  
• Consider fabricating brackets or guards if OEM parts are unavailable
  

A scrapyard in Ohio reported that Fiat-Allis loaders are still popular among small contractors who value simplicity over brand prestige. They often buy two machines—one for work, one for parts.
Operator Experience and Ergonomics
The 645B’s cab is utilitarian but functional. Visibility is good, thanks to large windows and a sloped hood. Controls are mechanical, with levers for loader functions and a column-mounted shifter. Noise levels are high, and climate control is minimal, but the seat is surprisingly comfortable for its era.
Suggestions for comfort upgrades:

• Install sound-deadening mats on the floor and firewall
  
• Replace the seat with a suspension model
  
• Add LED work lights for night operations
  
• Use magnetic fans or heaters for seasonal comfort
  

One operator in Saskatchewan added a Bluetooth speaker and a 12V charging port, turning his loader into a mobile office during long snow removal shifts.
Legacy and Market Position
The Fiat-Allis 645B may not be a household name, but it holds a place in the lineage of practical, operator-focused equipment. Its mechanical design, robust engine, and straightforward hydraulics make it a favorite among those who prefer wrenching to diagnostics.
While newer loaders offer joystick controls, telematics, and emissions compliance, the 645B delivers raw power and reliability. For small quarries, municipal yards, and rural contractors, it remains a viable option—especially when budgets are tight and downtime is not an option.
Conclusion
The Fiat-Allis 645B is more than a relic—it’s a reminder of an era when machines were built to be fixed, not replaced. With proper care and a bit of ingenuity, this loader can still move mountains, one bucket at a time. Whether you’re grading gravel or feeding a crusher, the 645B proves that old iron still earns its keep.