Logger contains information about the Forestry mod which is not included in the current recommended version of Technic Pack and might be outdated..
The logger cuts down all the trees in its area of operation. Its area of operations is 21x10x21 (X-Y-Z), with the base of any tree harvested being no higher than 10 but will harvest to the top of the tree. As a side operation, the logger does also pick up any saplings and apples that drop in its area. It needs to be powered by a Buildcraft compatible engine or an engine provided by forestry.