工程机械行驶液压传动不仅具有良好的无级调速性能和灵活布局的特点，而且可以进行多种多样的调节和控制。特别是与计算机控制技术相结合，可以实现工程机械智能化、节能化、环保化。因此，对行驶液压传动的研究就成为工程机械现代化的重要课题。 装载机是一种作业效率高、机动灵活、用途广泛的工程机械，作业工况复杂多变，负荷变化频繁、变化范围大。如何最简单而又适宜地使发动机和传动系统同外部负荷之间始终保持最合理的匹配，一直是装载机牵引系统长期以来存在的问题。 采用液压传动，并辅以适当的控制装置与之配合，可以形成理想的传动系统，它能使发动机的转速及其扭矩适应外部负荷的变化而连续变化，并且保持高效率。分析发动机、液压传动系统和负荷组成的负荷驱动系统，针对各作业工况不同的负荷要求，提出最适合于发动机和液压系统的最合理的控制原理及装置是论文研究的主要目的。 本论文以ZLY06型装载机为对象，对其行走液压传动系统进行设计，并对系统各参数进行合理配置，研究的主要内容包括以下四个方面：一是设计了装载机行走液压系统。根据装载机作业特点，从简单高效的角度考虑确定采用了变量泵—定量马达的开式容积调速系统。二是分析了发动机、液压系统的匹配机理，提出使用变量泵电液比例控制，通过调节泵排量变化来适应负载变化，实现恒扭矩控制。三是对装载机作业的不同工况进行动力学研究，对液压系统各元件参数选择及匹配。四是使用MATLAB/SIMULINK对所选用的液压系统及控制装置进行了动态仿真，研究在负载变化的情况下，泵出口压力、流量和马达输出转速的变化情况。 论文通过对装载机行驶液压传动特性的研究，试图为其他各种行走机械液压传动设计提供一种思路、方法和途径

Hydraulic transmission of the engineering machinery walk has not merely with good stepless speed regulation performance and flexible overall arrangement Characteristic, and can carry on varied regulation and control . Especially combined with control technology of computer, the engineering machinery can realize the intelligent, energy-conservation, environmental protection. Therefore, the research of hydraulic transmission for walking engineering machinery to modernized becomes the mainly content. The loader is a kind of engineering machinery working with high efficiency , flexible and wide use range, its operating mode of the work is complicated and changeable,and load changes frequently , the change range is greatly. How most simple to afford a suitable forly all the time, it has been the question that existed for a long time in the loader driving system. To adopt hydraulic transmission, complemented with the proper control device to cooperate, can form the ideal transmission , which can make the rotational speed and torsion of the engine changing in succession to meet the change of external load , and keep the high efficiency. It will be analysed that the load driving system which is made up of the engine , hydraulic pressure transmission and load. With the require to the load of every work in different operating mode, how to put forward a most rational control principle and device which is suitable for engine and hydraulic system is the main purpose that thesis study. The thesis is to design the walk hydraulic transmission of the ZLY06 loader , to dispose all parameter rationally in system. The main content of study includes four as followed respects: First, Design the walk hydraulic system of the loader. According to the characteristic of loader work, the adoption of the open volume transfer speed system that made up of variable pump and quantitative modor is confirmed , considered from simple and high-efficient. Second , analysed the match of mechanism between the engine and hydraulic system , proposed to use the electric-hydraulic proportion control of the variable pumpr, which is adapt to load change through regulating the displacement change of the pump,which it is to control the torsion is fixed. Third , carry on dynamics research to different operating modes of the loader work , carry on the parameter to choose and match to every component of hydraulic system. Fourth , use MATLAB/SIMULINK to carry on dynamic simulation to the hydraulic system selected for used and control device, studying the pump exports the pressure , flow and change of outputting the rotational speed of motor in case of changing in load. The thesis passes the research of hydraulic transmission characteristic that the loader goes correctly, attempt to offer a kind of train of thought , method and way for the thing that other various kinds of walk mechanical hydraulic transmission is designed.