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Spar (tree)
A spar tree is the tree used as the highest anchor point in a high lead cable logging setup. The spar tree is selected based on height, location and especially strength and lack of rot in order to withstand the weight and pressure required. Once a spar tree is selected, a climber would remove the tree's limbs and top the tree (a logging term for cutting off the top of the tree). Block and tackle is then affixed to the tree and cabling is run. A "high climber" is the member of the logging crew who scales the tree, limbs it, and tops it. Selecting a tree as a spar is a particularly important task, so the strength and importance of the spar came to hold symbolic meaning for early loggers of the West. The use of spar trees in logging is now rare, having been replaced since the 1970s by portable towers, called yarders A yarder is piece of logging equipment that uses a system of cables to pull or fly logs from the stump to a collection point. It generally consists of an engine, d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yarding Operation Using Spartree, Unidentified Logging Camp, Washington, 1924 (KINSEY 2803)
In poultry keeping, yarding is the practice of providing the poultry with a fenced yard in addition to a Chicken coop, poultry house. Movable yarding is a form of managed intensive grazing. Yarding is often confused with free range. The distinction is that free-range poultry are either totally unfenced, or the fence is so distant that it has little influence on their freedom of movement. Historical practice Before the discovery of vitamins A and D in the 1920s, green feed and sunshine were essential to the health of poultry. Vitamin D was synthesized from sunlight on the skin (as with humans), while vitamin A was obtained through green forage plants such as grass. Yards small enough to be fenced economically were soon stripped of palatable green forage and become barren. This is followed by a build-up of manure, parasites, and other pathogens. Free range husbandry was the most common method in these early days. Most farms had only a small free-range barnyard flock. Larger floc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Lead Logging
High lead logging is a method of cable logging using a spar, yarder and loader. It was developed by Oscar Wirkkala. It is accomplished with two lines (cables) and two winches (or cable drums). The mainline or yarding line extends out from one winch, while a second usually lighter line called the haulback line extends out from the other winch to a 'tail block' or pulley at the tail (back) end of the logging site, and passes through the tail block and connects to the main line. Butt rigging is installed where the two lines join and the logs are hooked to the butt rigging with chokers. The procedure is to wind up the main line and the logs are pulled in, wind up the haulback and the butt rigging is pulled out for more logs or another 'turn'. The "high lead" feature is added by elevating both lines near the winch or 'head' end. This is accomplished by running the lines through a block (pulley) called the "head block" because it is on the head end of the project. Early on, it wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cable Logging
High Lead logging in Western Oregon Cable logging, also referred to as skyline logging, is a logging method primarily used on the West Coast of North America with yarder, loaders, and grapple yarders, but also in Europe (Austria, Switzerland, Czech Republic, France, Italy). The cables can be rigged in several configurations. There are two classes; # High lead logging, in which a simple loop of cable runs from the yarder out through pulley blocks anchored to stumps at the far end of the cut. # Skyline, in which a carriage, pulled by hauling cables, runs along a skyline cable, providing vertical lift to the logs. There are other varieties of loading systems as well. While skyline logging requires additional setup, the vertical lift of the skyline allows faster yarding, which can outweigh the additional labor costs, especially on larger harvest units. Since the 1980s grapple yarders have become popular. Skyline and grapple yarding, however, require more complex, and expensiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block And Tackle
A block and tackle or only tackle is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads. The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load. The rope is threaded through the pulleys to provide mechanical advantage that amplifies the force applied to the rope. Hero of Alexandria described cranes formed from assemblies of pulleys in the first century. Illustrated versions of Hero's ''Mechanica'' (a book on raising heavy weights) show early block and tackle systems. Overview A block is a set of pulleys or sheaves mounted on a single frame. An assembly of blocks with a rope threaded through the pulleys is called tackle. The process of threading ropes or cables through blocks is called "reeving", and a threaded block and tackle is said to have been "rove". A block and tackle system amplifies the tension force in the rope to lift heavy loads. They are common ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yarders
A yarder is piece of logging equipment that uses a system of cables to pull or fly logs from the stump to a collection point. It generally consists of an engine, drums, and spar, but has a range of configurations and variations, such as the swing yarder. Early Yarders The early yarders were steam powered. They traveled on railroads, known as "dummylines", and felled trees were dragged or "skidded" to the railroad where they were loaded onto rail cars. Popular brands included Willamette, Skagit, Washington, Tyee, or Lidgerwood and Clyde, built by Clyde Ironworks in Duluth, Minnesota. Although these machines appear to be large and cumbersome, they were highly productive. The Clyde was capable of retrieving logs from four different points at the same time. Each cable, or lead, was approximately 1000 feet in length. Once the logs were attached and a clearance signal was sent for retrieval, the logs could be skidded at a speed of 1000 feet per minute, which is around 10 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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