Powering a Hydraulic Brush Chipper Attachment: Design, Requirements, and Safe Operation

[MikePhua]

Introduction
Hydraulic brush chippers enable compact track loaders (CTLs), skid-steers, and excavators to transform brush and limbs into mulch effortlessly. Proper hydraulic power configuration is essential for safe, efficient, and effective chipper operation.
Machine Compatibility and Hydraulic Flow

• Many CTLs and skid-steers offer standard‑flow auxiliary hydraulics (typically 16–26 gpm) with ½″ flat‑face couplers .
  
• High‑flow systems (27–45 gpm) use ¾″ couplers and are designed for demanding attachments like large chippers or drum mulchers .
  
• The brush chipper’s hydraulic motor must match your machine’s flow. Running a high‑flow chipper on standard hydraulics can lead to slow feed, inefficiency, and premature wear .
  

Hydraulic Power Requirements

• Brush chipper models like Quick Attach “Big Chipper” require 15–25 gpm @ 3,000 psi to spin the cutting rotor effectively .
  
• Low-flow chippers (11–12 gpm) can perform adequately in certain conditions, especially on steep terrain or less-dense brush, with minimal compromises .
  

Valve Switch Interlocks and Continuous Flow

• Many machines feature hydraulic lockout switches or seat/door interlocks, which shut off auxiliary flow if the operator exits the cab .
  
• Replacing a standard two-position switch with a three-position interlock override switch (e.g. Cat part 263‑5415) allows continuous flow while leaving the seat or opening the door—enabling safe remote chipper operation .
  

Installation and Control Considerations

• Auxiliary hydraulic kits must include properly sized hoses, couplers, and control valves (wet‑kits or plumbing kits) to function reliably .
  
• Flow control valves on the return side can provide full flow in one direction and adjustable flow in the other, controlling feed rollers and spindle pressure efficiently .
  
• Quick‑coupler compatibility with your machine’s coupler size and pressure rating is vital for safe interconnection .
  

Real-World Use Case
An operator with a Cat 259D3 CTL and Erskine chipper successfully improved functionality by upgrading to the factory’s recommended override switch. This allowed the machine to power the chipper while the operator safely exited the cab, matching the factory demonstration setup .
Technical Terms Simplified

• Auxiliary Hydraulics (Auxiliaries): Additional hydraulic circuit for powering attachments.
  
• Standard vs High Flow: Describes the amount of hydraulic fluid delivered—higher flow equates to more power for larger tools.
  
• Flow Control Valve: Regulates hydraulic flow direction and rate for functions like feeding.
  
• Hydraulic Interlock Switch: Disables flow when operator leaves seat/opens door.
  
• Quick-Coupler: Connectors enabling rapid, safe hooking of hydraulic lines.
  

Operating and Safety Tips

• Match chipper flow rating with machine output; if unsure, start with flow 5–10% below max to ensure cooler operation and longevity .
  
• Verify existing wiring: Many machines are pre-wired for three-position switches—check behind the panel before rewiring .
  
• Always park the machine securely, apply parking brake, and ensure safety shut‑off protocols before exiting the cab.
  
• Keep hoses, couplers, and valves clean and well-maintained to avoid contamination or pressure loss.
  

Summary Checklist

• Hydraulic Flow Required: Confirm chipper needs and machine’s flow capacity.
  
• Coupler Type: Standard (½″) vs. high‑flow (¾″), plus case drain size.
  
• Interlock Override Switch: Ensures continuous hydraulic when operator exits.
  
• Flow Control Valving: Regulates feed speed vs. rotor speed.
  
• Safety Setup: Operator exit protocols, cab door, seat switch settings.
  

Conclusion
Safely and efficiently powering a hydraulic brush chipper requires proper flow matching, interlock configuration, and hydraulic plumbing setup. Upgrading controls and using correct valves ensures chipper operations can continue while the operator works outside the cab. Adhering to recommended flow settings and safety practices maintains machine performance and extends attachment life without risking operator safety.