Adding a Fourth Hydraulic Line to a Volvo L70 Loader

[MikePhua]

The Versatility of the Volvo L70 Platform
The Volvo L70 wheel loader has long been a favorite among contractors, municipalities, and material handlers for its balance of power, maneuverability, and operator comfort. Introduced in the early 1990s and refined through successive generations, the L70 series sits in the mid-size class, typically offering around 160 horsepower, an operating weight near 30,000 lbs, and a bucket capacity of 2.5–3.0 cubic yards. Its popularity stems from its ability to handle everything from snow removal and aggregate loading to pallet handling and forestry work.
Volvo’s hydraulic system on the L70 is known for its smooth response and modular design. Most units come equipped with third-function hydraulics, allowing the use of attachments like grapples, snow blades, and forks with hydraulic tilt. However, some applications—especially those involving multi-function tools—require a fourth hydraulic line.
Why Add a Fourth Hydraulic Line
The need for a fourth hydraulic circuit typically arises when using attachments that require independent control of two hydraulic functions. Examples include:

• Grapples with independent clamp and rotate functions
  
• Snow plows with angle and lift cylinders
  
• Forks with side-shift and tilt
  
• Mulchers with hydraulic door and tilt
  
• Bale clamps with dual jaw control
  

Terminology notes:

• Third-function hydraulics: A circuit beyond lift and tilt, usually controlled by a joystick button or auxiliary switch.
  
• Fourth-function hydraulics: An additional circuit allowing simultaneous or independent control of a second attachment function.
  

In Ontario, a contractor retrofitted his L70 to run a rotating log grapple. The third line controlled the clamp, but without a fourth line, rotation was impossible. After the upgrade, productivity doubled in sorting operations.
Planning the Installation
Before adding a fourth hydraulic line, several factors must be considered:

• Compatibility with existing valve block and joystick controls
  
• Routing space along the loader arms
  
• Pressure and flow requirements of the attachment
  
• Electrical integration for solenoid valves or switches
  
• Return line capacity and cooling system adequacy
  

Recommended steps:

• Identify the attachment’s hydraulic needs (flow, pressure, number of functions)
  
• Inspect loader’s valve block for available ports or expansion slots
  
• Choose between electric-over-hydraulic diverter valves or dedicated spool
  
• Plan hose routing with protection from pinch points and abrasion
  
• Add quick couplers with dust caps for attachment interface
  

In Florida, a grading crew added a fourth line using a diverter valve controlled by a thumb switch on the joystick. The system allowed toggling between clamp and rotate without modifying the loader’s main valve block.
Hydraulic Components and Configuration
Key components for a fourth-line retrofit include:

• Hydraulic hoses rated for system pressure (typically 3,000–4,000 psi)
  
• Quick couplers (flat-face preferred for cleanliness)
  
• Diverter valve or auxiliary spool
  
• Electrical switch or joystick button
  
• Wiring harness and fuse protection
  
• Hose clamps and protective sleeves
  

Terminology notes:

• Diverter valve: A solenoid-controlled valve that redirects flow from one circuit to another.
  
• Flat-face coupler: A type of hydraulic quick connect that minimizes fluid loss and contamination.
  

In Chile, a mining crew used stainless steel braided hoses for their fourth line due to high abrasion risk. The added durability extended hose life by 60% compared to rubber lines.
Control Integration and Operator Ergonomics
Adding a fourth function requires thoughtful control placement. Options include:

• Joystick-mounted toggle switch
  
• Dash-mounted rocker switch
  
• Foot pedal for secondary function
  
• Automatic sequencing via programmable controller
  

Best practices:

• Use backlit switches for visibility
  
• Label controls clearly to avoid confusion
  
• Test ergonomics during operation to prevent fatigue
  
• Train operators on function sequencing and safety
  

In Tennessee, a contractor added a foot pedal for grapple rotation, freeing up both hands for clamp control. The setup improved precision during log sorting and reduced operator strain.
Safety and Maintenance Considerations
Additional hydraulic lines increase complexity and potential failure points. To maintain safety and reliability:

• Inspect hoses weekly for wear, leaks, or chafing
  
• Replace couplers annually or at signs of leakage
  
• Check valve operation during pre-shift inspection
  
• Monitor hydraulic fluid temperature and level
  
• Keep spare hoses and couplers on hand for field repairs
  

In South Africa, a vineyard crew added a pressure relief valve to their fourth line after experiencing cylinder lockup during hot weather. The valve prevented overpressure and protected the attachment.
Parts Availability and Sourcing Tips
Components for hydraulic retrofits are available through:

• Volvo Construction Equipment dealers
  
• Hydraulic supply shops with custom hose services
  
• Aftermarket vendors offering diverter kits and control modules
  
• Fabrication shops for bracketry and hose routing solutions
  

Sourcing advice:

• Match hose diameter and pressure rating to OEM specs
  
• Use couplers with compatible thread and seal type
  
• Seek valve blocks with expansion ports or modular design
  
• Replace electrical connectors with weatherproof types
  

In New Zealand, a contractor built his fourth line using surplus parts from a retired loader. After adapting the valve block and wiring, the system worked flawlessly with his snow blade.
Operator Stories and Field Wisdom
In Poland, a snow-clearing team added a fourth line to control plow angle independently. After installing a joystick toggle and quick couplers, they reduced pass time by 30% on city streets.
In Alberta, a forestry crew used a fourth line to operate a rotating grapple. The added function allowed precise log placement and reduced cycle time during loading.
Conclusion
Adding a fourth hydraulic line to a Volvo L70 loader unlocks new capabilities and expands the range of compatible attachments. With careful planning, quality components, and thoughtful control integration, the upgrade enhances productivity without compromising safety or reliability. Whether handling logs, snow, or debris, the fourth line turns a versatile loader into a multi-function powerhouse.