08-14-2025, 03:34 PM
Matching Up Equipment: Why This Combination Makes Sense
In forestry operations, adaptability can unlock huge productivity gains. A logging crew had a Timberjack 950 feller buncher—reliable, powerful, and fitted with a hot-saw—but they also owned a Hultdins 850 Super fell head from a retired Cat 325. They envisioned swapping between the chainsaw head and the felling head depending on terrain and task, aiming for versatility without investing in a second machine.
Key Terms Explained
Technical and Hydraulic Considerations
Integration Plan: Key Modifications and Controls
Real-World Considerations & Tips
Summary of Key Integration Steps
Mini-Story from the Yard
A logger once faced a patch of heavy blowdown on a remote ridge. Using the hot-saw slowed them down amongst tight spacing and uneven terrain. He remembered the Hultdins head stored in his yard and rigged this hybrid setup overnight. The next day, switching heads mid-shift saved him hours—and fuel. The retrofit involved long days fabbing hydraulic lines and fitting the control switch, but when it worked, he joked: “I invented the Swiss army tool of bunchers.”
Conclusion & Tips for Success
In forestry operations, adaptability can unlock huge productivity gains. A logging crew had a Timberjack 950 feller buncher—reliable, powerful, and fitted with a hot-saw—but they also owned a Hultdins 850 Super fell head from a retired Cat 325. They envisioned swapping between the chainsaw head and the felling head depending on terrain and task, aiming for versatility without investing in a second machine.
Key Terms Explained
- Felling head: An attachment that grips and cuts trees at the base, enabling efficient bunching of stems.
- Hot-saw: A chainsaw-style cutting system integrated into forestry machinery for fast stem cutting.
- Valvebody: Central hydraulic control assembly with multiple sections to manage fluid to various attachment functions.
- Electric-over-hydraulic valve (E-H valve): A valve activated electrically, but controlling hydraulic flow—often integrates joystick signals.
- Pump flow and pressure spec (GPM @ PSI): Measures hydraulic output—critical for ensuring the head gets sufficient oil volume and pressure for cutting and tilt.
Technical and Hydraulic Considerations
- The Hultdins 850 requires about 50 GPM at 4700 PSI for the saw function.
- The Timberjack 950’s hydraulics include:
- Main pump: ~126 GPM @ 5400 PSI (for travel, swing, boom)
- Saw pump: ~20 GPM @ 4700 PSI
- Implement pump: ~32 GPM @ 2700 PSI (for clamps, wrist, tilt)
- Main pump: ~126 GPM @ 5400 PSI (for travel, swing, boom)
- The saw pump alone lacks sufficient volume, so tapping into the main pump is necessary.
- A new valve section will be added to the existing 9-section main valve bank, using electric-over-hydraulic control to drive saw activation and tilt dump during saw operation .
Integration Plan: Key Modifications and Controls
- Fabricate mechanical interface:
- Use an old hot-saw wrist knuckle mounted on a heel rack to mate the Hultdins head to the Timberjack stick.
- Use an old hot-saw wrist knuckle mounted on a heel rack to mate the Hultdins head to the Timberjack stick.
- Hydraulic Routing:
- Add a valve section for saw and tilt functions.
- Route oil from the main pump via new pilot-activated valve section.
- Add a valve section for saw and tilt functions.
- Control Scheme:
- Install a 3-way rocker switch and a two-way toggle on the joystick (mimicking original Hultdins controls) to:
- Activate the saw
- Engage tilt dump during saw period
- Activate the saw
- Electric-over-hydraulic dump valve ensures smooth tilt reset.
- Extend electrical and hydraulic lines to stick end with quick-connects for easy head swapping.
- Install a 3-way rocker switch and a two-way toggle on the joystick (mimicking original Hultdins controls) to:
- Flow Management:
- Combine clamp circuits to power grapple function (~37 GPM requirement) using implement pump flow efficiently .
- Combine clamp circuits to power grapple function (~37 GPM requirement) using implement pump flow efficiently .
- Hardware Upkeep:
- Consider high-strength Grade-7 tie-rod replacements for valve bolts.
- Modify the tank line hard-line if needed.
- Consider high-strength Grade-7 tie-rod replacements for valve bolts.
Real-World Considerations & Tips
- Weight and balance: The fell head may shift front-end dynamics; weighing the combined assembly is recommended, especially on slopes; an engineer advised assessing if extra counterweight is needed .
- Valve section placement: Options include above the swing section or above the boom section in the valve stack—porting differences may affect performance, so choose carefully.
- Swap-out simplicity: Use weather-pack connectors and quick-coupler hydraulic lines to simplify head switching in the field.
Summary of Key Integration Steps
- Fabricate heel-rack interface with hot-saw wrist connection
- Add valvebody section for saw/tilt functions
- Tap hydraulic flow from main pump for saw
- Create joystick-based electric-over-hydraulic control package
- Combine clamp flows for grappling
- Install quick-disconnect connectors and weather-proof wiring
- Assess load dynamics and reinforce if needed
Mini-Story from the Yard
A logger once faced a patch of heavy blowdown on a remote ridge. Using the hot-saw slowed them down amongst tight spacing and uneven terrain. He remembered the Hultdins head stored in his yard and rigged this hybrid setup overnight. The next day, switching heads mid-shift saved him hours—and fuel. The retrofit involved long days fabbing hydraulic lines and fitting the control switch, but when it worked, he joked: “I invented the Swiss army tool of bunchers.”
Conclusion & Tips for Success
- Meticulous planning of hydraulic flow, valve placement, and control routing ensures safe, functional integration.
- Consider dynamics and structural stress from added attachment weight and leverage.
- Maintain modularity—quick switching between heads preserves utility and uptime.
