1) Linear unit 
A yarder is piece of logging equipment which uses a system of cables to pull or fly logs from the stump to the landing. 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 `dummyl....
donkey-engine used in logging
A machine used in yarding timber. ... (05 Dec 1998) ... 
[n] - something a given number of yards long
yard donkey noun a winch (or system of winches) powered by an engine and used to haul logs from a stump to a landing or to a skid road