Reviving an International Harvester Forklift and Its Mechanical Legacy

[MikePhua]

The Rise of International Harvester in Industrial Equipment
International Harvester, founded in 1902 through the merger of McCormick and Deering, became one of the most influential manufacturers of agricultural and industrial machinery in the 20th century. While best known for its Farmall tractors and heavy-duty trucks, IH also produced a range of industrial forklifts during the mid-century boom in warehousing and manufacturing. These machines were built with the same philosophy that guided their agricultural equipment—durability, simplicity, and field-serviceable design.
By the 1960s and 1970s, IH forklifts were common in factories, rail yards, and ports across North America. Though exact production numbers are hard to trace, estimates suggest that IH sold tens of thousands of industrial lift trucks before divesting its equipment divisions in the 1980s. Many of these machines remain in use today, especially in rural operations and restoration circles.
Mechanical Layout and Powertrain Configuration
International Harvester forklifts typically featured:

• Inline four- or six-cylinder gasoline or diesel engines
  
• Manual or torque converter transmissions
  
• Chain-driven mast assemblies with hydraulic lift cylinders
  
• Pneumatic or solid rubber tires depending on application
  
• Mechanical steering with hydraulic assist in later models
  

The engine was often shared with IH tractors or light trucks, making parts more accessible. For example, the BD-264 inline-six was used in both forklifts and the Loadstar truck series. This interchangeability allowed operators to source parts from agricultural suppliers or salvage yards.
Hydraulic System and Mast Operation
The mast assembly was the heart of the forklift, consisting of:

• Dual lift cylinders with steel hydraulic lines
  
• Chain pulleys mounted on crossmembers
  
• Tilt cylinders connected to the carriage frame
  
• Load backrest and fork carriage with adjustable spacing
  

Hydraulic pressure was generated by a gear pump driven off the engine crankshaft or accessory belt. Fluid was stored in a reservoir integrated into the frame or counterweight. Operators controlled lift and tilt via spool valves mounted beside the steering column.
Common issues included:

• Leaking cylinder seals
  
• Worn chain links and pulleys
  
• Bent mast rails from overload or impact
  
• Sluggish lift due to clogged filters or low fluid
  

In one case from rural Indiana, a farmer used an IH forklift to unload seed pallets. After noticing slow lift response, he replaced the hydraulic filter and topped off the reservoir with ISO 46 fluid. The machine returned to full speed, saving him from renting a replacement during planting season.
Electrical System and Starting Challenges
Older IH forklifts used 6V or 12V electrical systems with basic wiring harnesses. Components included:

• Starter motor and solenoid
  
• Generator or alternator
  
• Mechanical voltage regulator
  
• Ignition coil and distributor
  
• Headlights and warning buzzer
  

Machines that sat idle for years often suffer from corroded terminals, brittle wires, and seized starters. Restoration typically involves:

• Replacing the battery with a modern sealed unit
  
• Installing a new starter solenoid and cleaning ground straps
  
• Upgrading to an alternator with internal regulation
  
• Rewiring ignition with modern connectors
  

In one restoration project in Quebec, a collector converted his IH forklift to electronic ignition and LED lighting. The machine started reliably even in sub-zero temperatures and was used to move firewood during winter.
Transmission and Drive Axle Considerations
IH forklifts used either manual gearboxes or torque converter transmissions. Manual units had a clutch pedal and gear shifter, while torque converter models featured a directional lever and foot throttle. Drive axles were solid steel with planetary reduction hubs.
Maintenance tips:

• Check transmission fluid every 100 hours
  
• Inspect axle seals for leaks
  
• Grease wheel bearings annually
  
• Replace worn clutch discs or torque converter seals
  

In one case from Oregon, a warehouse operator noticed gear slippage during uphill travel. The issue was traced to a worn clutch disc. After replacement, the forklift regained full pulling power and was able to load trailers without issue.
Parts Availability and Restoration Strategy
Finding parts for IH forklifts requires creativity:

• Cross-reference engine and transmission parts with IH tractors or trucks
  
• Use hydraulic seal kits from Parker or Eaton equivalents
  
• Fabricate mast components using local machine shops
  
• Source tires from industrial suppliers with vintage sizing
  

Recommended restoration steps:

• Identify model and serial number from frame plate
  
• Photograph hydraulic routing and electrical layout before disassembly
  
• Pressure test lift cylinders and flush hydraulic lines
  
• Replace all fluids and filters
  
• Rebuild carburetor or fuel injection system
  

In one restoration in Kansas, a mechanic rebuilt an IH forklift using parts from three donor machines. He fabricated a new mast crossmember and installed a modern seat with suspension. The machine was later used in a local parade showcasing vintage equipment.
Conclusion
International Harvester forklifts represent a bygone era of industrial design—machines built to last, with mechanical simplicity and interchangeable parts. Though no longer in production, these forklifts continue to serve in workshops, farms, and restoration yards. With patience, ingenuity, and a bit of grease, they can be brought back to life and put to work once again. Whether lifting hay bales or engine blocks, an IH forklift proves that good engineering never goes out of style.