JLG 70G Boom Lift Parts Sourcing and Restoration Strategy

[MikePhua]

The 70G and JLG’s Legacy in Aerial Equipment
The JLG 70G boom lift was part of JLG Industries’ early generation of gas-powered telescopic aerial platforms, designed for construction, maintenance, and industrial access. With a working height of approximately 76 feet and a horizontal outreach exceeding 60 feet, the 70G offered impressive reach for its time. Its robust steel frame, mechanical simplicity, and analog control system made it a favorite among rental fleets and contractors in the 1980s and 1990s.
JLG Industries, founded in 1969, pioneered the aerial work platform market in North America. The company’s early models like the 60G and 70G helped define the standard for boom lift design before the widespread adoption of electronic controls and hybrid powertrains. Though the 70G is no longer in production, many units remain in service, especially in rural and industrial settings where simplicity and reliability are valued.
Core Components and Wear-Prone Assemblies
Restoring or maintaining a JLG 70G requires attention to several key systems:

• Hydraulic System
  • Gear pump or vane pump delivering flow to lift, extend, and steer functions
    
  • Steel hydraulic lines and hoses with crimped fittings
    
  • Manual valve block with spool-type directional controls
    
  • Lift cylinder with dual-stage extension and internal wear bands
    
• Boom Assembly
  • Telescoping steel sections with wear pads and guide rollers
    
  • Chain or cable retraction system with tensioning pulleys
    
  • Boom pivot pins and bushings subject to side load stress
    
  • Platform rotator and tilt cylinder with exposed seals
    
• Chassis and Drive System
  • Gasoline engine, typically Ford industrial or GM 4-cylinder
    
  • Hydrostatic drive motors with planetary reduction hubs
    
  • Steering cylinder and tie rod assembly
    
  • Manual outriggers or stabilizers on some variants
    
• Electrical and Control Panel
  

• Toggle switches and analog gauges for fuel, battery, and hydraulic pressure
  
• Limit switches and interlocks for boom angle and extension
  
• Starter solenoid and ignition coil prone to corrosion
  
• Platform control box with joystick and emergency stop
  

A technician in Alberta rebuilt a 70G’s boom extension system by fabricating new wear pads from UHMW polyethylene and replacing the chain tensioner with a custom-machined bracket. The lift regained full extension capability and smoother retraction.
Parts Availability and Sourcing Strategies
Due to the age of the 70G, OEM parts may be discontinued or difficult to locate. Strategies for sourcing include:

• Cross-Referencing
  • Match hydraulic components with Parker, Eaton, or Char-Lynn equivalents
    
  • Identify engine parts using block casting numbers and industrial catalogs
    
  • Use bearing and seal dimensions to source from SKF or Timken
    
• Salvage and Rebuild
  • Locate donor machines from rental yards or auctions
    
  • Rebuild hydraulic cylinders using aftermarket seal kits
    
  • Fabricate brackets, bushings, and guards using original dimensions
    
• Specialty Suppliers
  

• Contact aerial lift parts distributors with legacy inventory
  
• Use online platforms to locate control boxes, joysticks, and wiring harnesses
  
• Retrofit newer components with adapter plates and wiring conversions
  

A restorer in Texas replaced the entire control panel on a 70G using a universal joystick and a custom relay board. The retrofit improved reliability and allowed integration with modern safety interlocks.
Maintenance Protocols and Inspection Priorities
To keep a JLG 70G in safe working condition, regular inspection and maintenance are essential:

• Hydraulic Fluid
  • Change every 500 hours or annually
    
  • Use ISO VG 46 or 68 depending on climate
    
  • Monitor for contamination and water ingress
    
• Boom Wear Pads and Rollers
  • Inspect monthly for cracking or excessive wear
    
  • Replace when clearance exceeds manufacturer spec
    
  • Lubricate rollers and pivot points with lithium grease
    
• Engine and Drive System
  • Tune-up every 250 hours: plugs, filters, belts
    
  • Check hydrostatic drive fluid and filter
    
  • Inspect tires for cracking and tread separation
    
• Safety Systems
  

• Test emergency stop and platform lowering function
  
• Verify boom angle limit switches and tilt sensor
  
• Inspect harness anchor points and platform guardrails
  

A crew in Florida added a checklist protocol for their aging 70G units, reducing downtime and improving operator safety during warehouse maintenance operations.
Restoration Tips and Field Modifications
Restoring a 70G can be rewarding but requires creativity and mechanical skill. Tips include:

• Use original manuals or parts diagrams to guide disassembly
  
• Label hydraulic lines and electrical connectors during teardown
  
• Replace all rubber components—hoses, seals, grommets—regardless of appearance
  
• Upgrade lighting and safety decals to meet current standards
  
• Consider repainting with industrial enamel and rust inhibitor primer
  

In one restoration, a technician in Chile converted a 70G to propane power using a forklift-style vaporizer and tank mount. The modification reduced emissions and improved cold start reliability.
Conclusion and Recommendations
The JLG 70G remains a capable and serviceable boom lift despite its age. With careful inspection, targeted upgrades, and creative sourcing, it can continue performing in industrial, agricultural, and construction settings.
Recommendations include:

• Identify critical wear components and source replacements proactively
  
• Retrofit modern controls and safety systems where feasible
  
• Maintain hydraulic cleanliness and monitor boom alignment
  
• Document all modifications and service intervals
  
• Network with other owners and restorers for shared resources
  

With the right approach, the 70G becomes more than a legacy machine—it becomes a reliable workhorse adapted for today’s jobsite demands.