Logging; the principles and general methods of operation in the United States . aders. — There are several types of power unloadersused which are employed chiefly on the Pacific Coast where largeand long logs are handled. However, some t>pes are used in theLake States and in the hardwood region. Swinging-boom log loaders which pick logs from the car anddeposit them on either side of the track are among the devicesused where logs are stored in piles on dry ground. An overhead cableway system, supported on two spars from500 to 600 feet apart and spanning the railroad track on which thelogs ar
Logging; the principles and general methods of operation in the United States . aders. — There are several types of power unloadersused which are employed chiefly on the Pacific Coast where largeand long logs are handled. However, some t>pes are used in theLake States and in the hardwood region. Swinging-boom log loaders which pick logs from the car anddeposit them on either side of the track are among the devicesused where logs are stored in piles on dry ground. An overhead cableway system, supported on two spars from500 to 600 feet apart and spanning the railroad track on which thelogs are brought in, is another scheme employed where logs arestored in piles. The trolley is operated in a manner similar tothe overhead cableway logging system (page 198). An ingenious device called a log dump is used at some built in Washington consists of two dumps separated by30 feet of stationary track, the entire structure being supportedon piling.^ The platform of each dump is 40 feet long and 1 The Timberman, August, 1912, p. 68. LOADING AND UNLOADING CARS 335. 336 LOGGING consists of four latch timbers {A), which are ii feet long anda fifth timber (B), known as the trip timber, which is 36 feetlong and of larger size. The frame is hung on a roller timber (C) 18 by 18 inches square and 40 feet 2 inches long which restson heavy cast-iron sills. The roller timber is bound w^ith aniron cylinder to facilitate its rotation. This roller is placedoff-center, the distance between the rail on the land side and thecenter of the roller timber being 2^ inches. WTien the latches (D) holding the frame are released the weight of the load willautomatically tip the frame tow^ard the brow skid (E) throughan arc of 15 degrees. In operation, the cars are run on the dump,the chains holding the logs on the cars removed, and the latches(D) opened. The dump then revolves until the car bunk restson the brow skid (E). The majority of the logs will roll off,although some must occasionally
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