1998 harvesting head buyer's guide: dangle versus fixed mount [with list of selected features]

Canadian Forest Industries, Apr/May 1998 by Jamieson, Scott

Welcome to our fourth biannual guide to the harvesting heads available to North American loggers. This guide is more complete than ever, both in terms of the models featured and the amount of information included. The heads are divided into two basic categories -- fixed-mount and "dangle" (directional felling) -- and we've included a few comments to help you decide which of these designs is right for you.

Despite our best efforts to contact all harvesting head suppliers, only those that responded to our surveys are included. But very few are missing (we have also left off heads that are not available here, like Timberjack's multi-stem head). Also note that the specifications and general comments starting on page 26 have been supplied by the head manufacturers. While we have ensured that the claims and numbers are reasonable, Canadian Forest Industries Magazine cannot vouch for the accuracy of the information.

For more information on the heads listed here, please circle the appropriate reader reply number on the postcards on p. 16 and mail them, or fax to (514) 457-2558.

Dangle versus fixed mount

To dangle or solid mount? For many loggers either involved in or thinking about cut-to-length (CTL) harvesting, that is indeed the question. While we at CFI don't have the definite answer, we have given the question a lot of thought over the years, and have assembled a list of pros and cons for each attachment type. We have it will help you analyse which harvesting head is best suited to your range of forest conditions, tree types, operational experience, and the availability of skilled operators in your area. Please remember that this list of advantages and disadvantages is very general and somewhat subjective, and might not apply to all harvesting heads on the market as manufacturers continue to strive for one head that can do it all.

Dangle-Type Harvesting Heads

Pros

- Generally lighter than fixed-mount heads of similar tree capacity. Loggers can thus opt for smaller carriers with lower capital costs and less site disturbance.

- For same reason, dangle heads can be attached to lighter, faster, and more precise purpose-built cranes (i.e. parallel action cranes on wheel harvesters).

- Smaller in stature -- less intrusive in the forest.

- Suited for wheel or track machines.

- Can be mounted to long-reach telescopic booms and/or cranes for up to 10 m reach.

- Because of the above, and the rotate mount on these heads, dangle heads generally cause less residual damage in softwood selection cuts or commercial thinning (CT). The smaller size and more precise cranes (when used with a purpose-built wheel or some track harvesters) can remove the smaller diameter tree without scarring the leave trees, and can generally do so faster than fixed-mount heads on excavator booms.

- In deep snow, the shape and configuration allow "boring" down the stem for low stumps if used properly.

- Potential for lower capital cost systems when working in softwood CT or selection cuts, as there are a large number of small harvesting heads available for either small excavators or hybrid wheel harvesters (i.e. Rocan T, Enviro, Komatsu PC 90).

- The fixed heads are typically larger and beefier (i.e. Ultimate, Rolly II), designed for mixed-wood or hardwood stands and thus over-built and over-priced for softwood CT work. As always, there are exceptions, such as the Hahn thinning head or smaller Fabteks that have been used on small Komatsu or Hyundai carriers for lower-cost, small-wood systems.

- Finally, it is generally true that in the right conditions (softwood, diameters in the 8- to 18-in range, medium-sized limbs less than 2-in in diameter and not too many near the bottom), dangle-style heads will out-produce the fixed-mount competition. This is because of the greater speed and mobility of the lighter head/crane or boom combo, and because a skilled operator and the head's ability to "float" during directional felling means that processing begins while the tree is still falling to the ground. A good operator can often have the first piece ready for bucking by the time the tree top hits the ground.

Cons

- Perceived as more fragile and "overly-sophisticated", for less reliability in the bush given the current level of operator expertise and technical education.

- Less operator familiarity and longer learning curve than "buncher-style" fixed mount heads. This is more of a problem in areas with few trained operators, like Northwestern Ontario, Alberta and B.C. than areas with a long history of CTL logging like the Maritimes and parts of Quebec.

- Not as well suited for hardwoods or mixed woods, especially in selection cuts where the ability to "walk with the tree" to avoid residual and crown damage can be vital. However, several dangle-head manufacturers have introduced mixed-wood versions of their heads. While these do not allow full stem control, they do boast such amenities as topping saws for dealing with forks or crowns and greater delimbing force (i.e. Denharco DHT 550, Logmax Extreme). Moreover, successful directional felling trials in mixed wood stands, as well as the fact that manual cutters have worked with minimal residual damage for years, seem to dispute the need for "full control" (see page 14 for the benefits of directional felling heads in hardwoods).