GROUND/WORKING IMPLEMENT DEPTH CONTROL SYSTEM

摘要

The working depth of an implement attached to the 3-point hitch of a tractor is normally controlled by a draft load error signal formed as the difference between a load set point signal and an actual load signal provided by a draft sensor. For lowering the implement into the ground and raising it a depth position lever (50) actuates a transducer (54) to provide a position set point signal A(3) which is compared with an actual position signal from another transducer to form a position error signal. A large position error takes precedence over a smaller load error. In order to provide the load set point signal without the need for a separate lever, a swith (58, 60) is mounted on the lever (50) and, when depressed, causes the draft load set point signal to increase up to the desired value as the implement is lowered into the ground by pushing the lever (50) forwards.