Mark Industries 100C Manlift Requires Careful Inspection and Operational Familiarity

[MikePhua]

The Mark Industries 100C and Its Place in Aerial Equipment History
The Mark Industries 100C 6x4 manlift boom was part of a wave of high-reach aerial platforms developed in the late 1980s and early 1990s, designed to meet growing demand for elevated access in industrial maintenance, construction, and utility work. With a working height of approximately 100 feet and a 6x4 drive configuration, the 100C was built for stability, reach, and maneuverability on semi-rough terrain.
Mark Industries, though no longer active as a manufacturer, contributed to the evolution of self-propelled boom lifts with hydraulic outriggers, telescoping booms, and platform controls. Their machines were often used in shipyards, refineries, and steel plants where vertical access was critical.
Key Features and Operating Characteristics
The 100C manlift includes:

• Telescoping boom with hydraulic extension
  
• Articulating platform with joystick control
  
• 6x4 drive system for improved traction
  
• Hydraulic outriggers for leveling
  
• Diesel engine powertrain
  
• Manual override and emergency lowering systems
  

Operators must be familiar with:

• Boom extension sequencing
  
• Platform leveling under load
  
• Emergency descent procedures
  
• Stabilizer deployment before elevation
  
• Load chart and platform capacity limits
  

A technician in Ohio once operated a 100C during a refinery shutdown. He noted that the boom extended smoothly but required careful joystick modulation to avoid platform sway at full height.
Common Issues and Maintenance Considerations
Due to age and limited parts availability, the 100C may present challenges:

• Hydraulic leaks at boom cylinder seals
  
• Electrical faults in platform control wiring
  
• Corrosion in outrigger pivot points
  
• Engine wear or fuel system degradation
  
• Tire cracking or dry rot from long-term storage
  

Recommended maintenance includes:

• Replacing hydraulic hoses with modern equivalents
  
• Upgrading control wiring with sealed connectors
  
• Flushing hydraulic fluid and replacing filters
  
• Inspecting welds and boom structure for fatigue
  
• Testing emergency lowering system monthly
  

A restorer in Alberta rebuilt a 100C using parts sourced from similar-era JLG and Genie lifts. He fabricated new outrigger pins and replaced the control box with a universal joystick module.
Safety Protocols and Operational Tips
Working at 100 feet introduces unique risks:

• Wind sway and platform oscillation
  
• Boom bounce during rapid extension
  
• Electrical hazard near power lines
  
• Ground instability affecting outriggers
  
• Operator fatigue and spatial disorientation
  

To mitigate these risks:

• Deploy outriggers fully and verify level
  
• Avoid operation in winds exceeding 25 mph
  
• Use fall protection harnesses with anchor points
  
• Perform pre-use inspection of all hydraulic and electrical systems
  
• Train operators on emergency descent and manual override
  

A crew in Texas used a 100C to inspect stadium lighting towers. They implemented a two-person protocol: one operator in the basket and one spotter on the ground with radio contact.
Parts Sourcing and Cross-Compatibility
With Mark Industries no longer in operation, parts must be sourced creatively:

• Hydraulic cylinders and seals from Parker or Eaton
  
• Electrical components from aftermarket aerial lift suppliers
  
• Tires and wheels from industrial forklift distributors
  
• Engine parts from diesel rebuilders or salvage yards
  
• Control modules from universal aerial lift kits
  

A technician in Florida replaced the swing motor on a 100C using a surplus unit from a Skyjack lift. After minor bracket modifications, the motor fit and operated reliably.
Conclusion
The Mark Industries 100C manlift remains a capable high-reach platform when properly maintained and operated. Though parts may be scarce, its robust design and mechanical simplicity make it a viable tool for specialized access tasks. With careful inspection, thoughtful upgrades, and strict adherence to safety protocols, the 100C can continue serving in industrial environments where vertical reach is essential. In aerial work, stability and control are everything—and the 100C still delivers both when treated with respect.