| As science and technology develop, the whole world has stepped into an equipment revolution phase which takes the mechanical, electrical and fluid integration as the core. It is sure that the integration be applied to construction equipments. In recent years, construction equipments' development chiefly is the improvement of operation and control devices. In order to resolve the control problem ,if merely considering it from the viewpoint of mechanical and hydraulic pressure, it is hard to make the product have a qualitative leap and therefore it is necessary to introduce electron technique or electricity-fluid transformation technique with well control performance and message processing capability. Bulldozer is a main kind of construction equipments, which is widely used in the mining area, water conservancy, construction, road, harbor, the national defence and so on. The main missions that bulldozer undertakes are cutting and pushing which are used to excavate riverbed, pile dune, stack up roadbed, backfill trench, level off roadway, loosen wasteland, eliminate road-block and assist shoveling. For the sake of accelerating the product refresh pace, foreign construction equipment manufacturers attach importance to structure innovation and continuously adopt new electron technique and design manufacture technique on Bulldozer. Although domestic bulldozer has preliminary come into being a certain scale and made great progresses in manufacture technique, it still has greater distance from foreign advanced bulldozer. The main problems that domestic bulldozer manufacturers are confronted with are that the product structure is illogical and technique level is behindhand. Therefore, it is hard for domestic bulldozer manufacturer to compete with foreign counterparts. Along with the implementation of west great exploiture strategy and "ten-five" planning,our country increases investment for infrastructure to enlarge construction engineering and opencast exploitation scale. Due to the increased quantity of earthwork project, track bulldozer gets swift and violent development. At present, bulldozer's main problems exist in operating and control devices, which can't release drivers from strenuous and complicated operating work. Domestic bulldozer has two joysticks steer or brake. During working, driver must continuously regulate work outfit position and frequently alternate bulldozer's speed and direction. Frequent alternating to operate different joystick not only disperses driver's attention, affects working quality and productivity but also adds driver's labour intensity.In order to improve driver's working conditions and simultaneously enhance home-made bulldozer's grade, we are entrusted by No.1 machine manufacturing group in Inner Mongolia to develop bulldozer single-lever steering and braking electro-hydraulic proportional control system. This system adopts advanced electro-hydraulic proportional control technique and SCM control technique. Driver can control electro-hydraulic proportional decompression valve's output pressure by proportional electric signal emitted from single-lever, thereby control cylinder piston-rod's position to make steering valve or braking valve's handle turn and carry out steering or braking. Single-lever in cab connects with electro-hydraulic proportional valve installed on crossbeam by wire and proportional valve connects with controlled cylinder by vitta. All joints are flexible, which makes cab's arrangement and design very simple. And operating effort on handle is very little(less than 3 newton). So this kind of control mode is called "fingertip control". It dramatically eases driver's labour intensity. Moreover, steering or braking process is controlled by SCM, thus we can conveniently alter control programme to obtain satisfied control properties and completely remove dead area resulting from lever's gap in traditional mechanical control scheme to enhance control accuracy and delicacy.The text is divided into six chapters.Chapter one firstly elaborates th...
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