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Mechanical linkages are often used with fluid power systems to produce desired operations or work. Linkages may be used in hydromechanical servomechanisms or as actuator powered machine members. Many examples can be found of linkages associated with fluid power systems, on construction and agricultural machinery. The reaction of linkage members to fluid actuator motion is of considerable interest to machine designers. This paper describes a method of using loop closure equations, from kinematics, to model and analize linkages configured with fluid power machinery.

The use of mechanical, electrical, electronic, computer, and control engineering concepts combined in a particular machine or process is occurring at an increasingly rapid pace. The integration of these concepts is referred to as mechatronics. Engineers and technicians now must have knowledge and skills in all of the areas mentioned. Mobile machines have always incorporated knowledge from a variety of areas as needed to incorporate desired features and work functions. However, the time has come to make a more formal recognition of this integration of ideas.

Many types of mechanical linkages are in use on fluid power equipment. Linkages are often used in hydromechanical servomechanisms and in actuator powered machine members used to accomplish desired working functions. Agricultural and construction equipment have many examples of linkages in use with fluid power systems. The motion of hydraulically actuated linkages is usually quite complex, because of the versatility of fluid power machinery. This paper explores some helpful concepts from kinematics to describe motion analysis of linkages. Linkage position, velocity, and acceleration may be covered by the method.

Determination of flow distribution is important in many types of fluid power machines. The life and proper operation of engines, transmissions, and fluid power equipment is dependent on satisfactory flow distribution of oil in the passages of the circuitry. Use of the hydraulic ohm provides a simplified and accurate method for determination of flow distribution and associated pressure values. The method provides a rapid solution and eliminates the need for the iterative type procedures commonly used.

Analysis of a fluid power system with the use of a mathematical model can provide much useful information for good design and safety of a machine. Analysis of a system may cover flow distribution, component operation, or a combination of both. A method is described in this paper, that allows inclusion of all aspects of a fluid system in a single mathematical model. The method may be used to predict circuit flow division simultaneously with component behavior.

The success of agricultural and construction machinery owes a great deal to the effective use of fluid power. Most fluid power systems are configured with a positive displacement fluid pump that is large enough to meet the flow requirements of many work circuits. Different work functions require a variety of fluid flow and pressure values to provide the desired operation. System branches, therefore, must include specialized flow and pressure regulating valves. The development of a mathematical model of a fluid flow control valve follows.

Pressure waves in hydraulic systems can cause control valves to become un-stable during operation and also contribute to vibration and noise. These undesirable pulses must be filter-filtered out or at least reduced in magnitude, in order to optimize the performance of fluid power systems and their controls. Reduction in pressure wave amplitude also reduces wear and damage to system parts [13].* The fluid pump is usually the primary source of pressure pulsations. These waves travel throughout the fluid system. Therefore, it becomes advantageous to reduce the amplitude of the pressure waves as close to the source as possible [16]. A method of reducing the pressure waves by use of a carefully selected volume in the flow line is described. A successful mathematical means of sizing the desired attenuator volume is outlined. The mathematical model can be used with any computer simulation program. Some of these are mentioned by Bowns and others [1,2,3,4,5,6,7,18,19].