Design of hydrostatic transmission of agriculture machines

This paper focuses on the use of hydrostatic transmissions for an agriculture machine. A hydrostatic transmission modifies and transmits power from the engine to the final drive, or directly to the wheels or tracks. An entire text could be devoted to the analysis required to properly match prime mover and load characteristics to achieve optimal productivity and efficiency. The objective in this paper is to understand the characteristics of a hydrostatic transmission so that it can be compared with mechanical transmissions

Static and dynamic characteristics of direct operated pressure relief valves

The static and dynamic characteristics of direct operated pressure relief valve, manufactured by BoschRexroth are presented in this study. Linear and nonlinear mathematic model of the valve in hydraulic system with volume of oil at its inlet and pipeline at its outlet are given. The linear model allows determining, with sufficient approximation, the maximum pressure values and the frequency of oscillations of the transient response

Modelling and Simulation of the Transient Performance of a Direct Operated Pressure Relief Valve

The dynamic characteristics determine variations of the inlet pressure in front of the valve in function of the flow through the valve in the time. In any hydraulic system, the valve is connected at least by a pipe at the outlet, and at its inlet there is some volume of compressible oil which influences the quality of the transient process. When switching the directional control valve in the hydraulic system with direct- operated pressure relief valves, a transient process occurs in which it is possible for the pressure to reach values many times higher than the set value. This causes the system to be overloaded with undesirable consequences. This paper examines experimentally and theoretically the transients in hydraulic systems with these valves. From the experimental static characteristics, the coefficient of hydrodynamic force acting on the valve poppet is determined

Theoretic research on transient process in hydraulic cylinder with cushioning device with constant gap

Hydraulic cylinders are devices that very often move large masses with high potential energy at high velocities. Abrupt stopping at its end positions, the hydraulic cylinders may damage or destroy itself or the whole system. To prevent the hydraulic system from damaging, the incorporation of the cushioning devices are introduced in the design of the hydraulic cylinder to help smoothly stop at the end position. In this work a mathematical model of a cushioning device with constant gap is developed and simulated the transient process at the end of its stroke

Elimination of preheating by determining suitable welding parameters

There are failures in hydraulic cylinders in industrial trucks after short operating times due to leakages in the field of welded joints. As a result, these products do not meet customer requirements for a permanently fatigue strength. These hydraulic cylinders consist of a pressure tube and cylinder-head and cylinder-bottom. The leaks that lead to the failure of the hydraulic cylinders have so far only been detected at the bottom of the cylinder (highest pressurization area). Against initial assumptions, preliminary investigations show that the leakagess are not due to porosity within the weld metal with the pressure medium (oil) diffused through it. These preliminary investigations show that the leakagess result from material separation covering the entire weld metal cross-section

Vehicle Routing Problem with Distance Constraints aAnd Clustering Using MATLAB

The problem of designing routes for vehicles that should supply different customers with defined locations and specific demand from a single or various depots is known as the vehicle routing problem. The main objective in this case is minimizing the total cost of delivery or maximizing the profit while taking into consideration some constraints that vary from a case to another. In this paper I am going to define this problem, present a mathematical model to describe it, talk about the existing solutions to solve it, and use different tools to solve a real VRP of a company in tangier

Конвенционални и нумерички управувани металорезачки машини и помагала

Учебникот „Конвенционални и нумерички управувани металорезачки машини и помагала“ е плод на повеќегодишна работа и стекнато искуство при реализацијата на наставата и истражувањата во оваа област од страна на авторите. Учебникот е наменет и е изработен според предметната програма за истоимениот предмет „Конвенционални и нумерички управувани металорезачки машини и помагала“, од студиската програма Производно машинство на Машинскиот факултет на Универзитетот „Гоце Делчев“ во Штип

Research on the influence of the volume of oil in front of the direct operated pressure relief valve on its transient performances

The dynamic characteristics determine variations of the inlet pressure in front of the valve in function of the flow through the valve in time. In any hydraulic system, at valve inlet port there is some volume of compressible oil which influences the quality of the transient process. When switching the directional control valve in the hydraulic system with direct-operated pressure relief valves, a transient process occurs in which, depending on the amount of oil in front of the valve, it is possible for the pressure to reach values many times higher than the set value. This causes the system to be overloaded with undesirable consequences. This paper examines experimentally and theoretically the influence of the volume of oil in front of the valve on its transient performances. It is presented that when there is a low amount of oil in front of the valve, it reacts faster, but the system is significantly overloaded. When there is a higher amount of oil in front of the valve, it reacts more slowly and overloads the system less above the preset value of the pressure

Improvement of the Static Characteristics of Pilot Operated Pressure Relief Valves

Theoretical and experimental investigations of the static characteristics of pilot operated pressure relief valves is presented in this article. A mathematical model of pressure drop vs. flow depending of pilot operated pressure relief valves is developed. An experimental test stand was created for experimental investigation of the static characteristics and compared with each other which confirm the mathematical model. The results of solving the mathematical model and experimental investigation are presented in few diagrams. A few directions for improvement of the static characteristics are given, especially at the moment of opening of the main valve. Advantages and disadvantages of the static characteristics are discussed

Matrix method for large scale systems analysis

The mathematical model of a pilot operated pressure relief valve is described by a large system of nonlinear differential and algebraic equations. To analyze the stability condition of the valve, linearization of the mathematical model and getting the transfer function, i.e., the characteristic equation of the system is necessary. Obtaining the transfer function with elimination of the intermediate parameters is very complex and sometimes impossible. In this paper, a state space matrix method is used to reduce the large system of equation and to get the transfer function of the system