Combine harvesters are used effectively on flat to moderately steep terrain to clear forest areas. For very steep slopes or for removing individual trees, people working with chainsaws are still preferred in some countries. Small and maneuverable combines in northern Europe are used for thinning operations, hand cutting is typically used in extreme conditions where tree size exceeds the capacity of the combine head or by small woodshed owners.
The intended principle in mechanized logging is “no feet on the forest floor” and the combine and forwarder allow this to be accomplished. Keeping people in the machine’s cab provides a safer and more comfortable working environment for industrial-scale recording.
Combines are built on a solid all-terrain vehicle on a wheeled, tracked or walking excavator. The vehicle can be articulated to provide tight turning around obstacles. A diesel engine vehicle provides power to both the harvesting arrangement via hydraulic drive. An expandable, articulated boom, similar to that on an excavator, extends from the vehicle to carry the harvester head. Some combines are adaptations of excavators with a new combine head, while others are purpose-built vehicles.
“Combi” machines are available that combine the felling capability of a combine with the load handling capability of a hauler, allowing a single operator and machine to fell, process and transport trees. These new types of vehicles can only compete in short-range operations to landing.
An operator in the car’s cabin can control all these functions. A control computer can simplify mechanical movements and keep records of the length and diameter of felled trees. The length is calculated by counting the turns of the clutch wheels, or more commonly using the measuring wheel. Diameter is calculated from the angle of rotation of the grip wheels or splitting blades as they hug the tree. Length measurement can also be used to automatically cut wood into predefined lengths. The computer software can estimate the volume of each stem by analyzing the stems harvested earlier. This information, when combined with price lists for each specific log specification, enables optimization of root log recovery.