Research On The Closed Type Hydraulic System For Walking Mechanism Of Skid Loader

Skid Loader is also called the Multi-Function Engineering Vehicle. It is one kind of Wheel Loader that possesses a special chassis-device; it uses the differential of line speed on both sides of wheels to accomplish the vehicle turning. Wheel walking mechanism, multi-wheels driving and sliding turn, these technologies are widely used in the Skid Loader, and for the various working conditions and working demands, some outer devices to the Skid Loader should be mounted and removed easily in short time on the working field. Mostly the closed type hydraulic system is introduced to control the walking mechanism of the Skid Loader. Structure of the closed type hydraulic system is simple, therefore it is easy to deploy the hydraulic pipe lines and the following maintenance would be convenience. By employing this system, transmission in the Skid Loader could be more stable, hydraulic shock and energy loss could be kept as lower as possible. This thesis is based on the development of "XT750 Skid Loader" The main task is to design and research the closed type hydraulic system for the walking mechanism in "XT750 Skid Loader". Analyze the closed type hydraulic system in detail; figure out the key techniques which are applied to this system, and compare to the open type hydraulic system in order to realize the advantages and disadvantages in the closed type hydraulic system. During the period of "XT750 Skid Loader' development, to the closed type hydraulic system there are three most important parts. First, analyze the properties of the closed type hydraulic system for the walking mechanism to design the hydraulic schematic diagram. According to the diagram, every signal part of the system is selected very particularly. Matching up and efficiency calculation provide the theoretical proven that the hydraulic system is feasible. Second, deduce the transfer functions about the closed type hydraulic system and the control system for the walking mechanism from analyzing the hydraulic system of "XT750 Skid Loader". Then set up the mathematic model, and optimize the hydraulic control system which based on the valve controlled cylinder to acquire a stabilized control system. Third, exam the "XT750 Skid Loader" systemically after fully assembled. Testing diagrams show that the walking system in "XT750 Skid Loader" has high level stabilization, and the whole system is easy to manipulate. Every indicator can meet the requirements of designer.