Hydraulic system designs for heavy equipment and other machinery must take into account how and where the system is to be used. In accordance with ISO 14121-1, a risk assessment must be conducted to ensure there are not any predictable risks in the design that could carry over into the field. Reasonably foreseeable misuse shall not cause hazards. If any portion of the hydraulic system design is unable to foresee potential risks in the field, then safeguards and warnings must be integrated into the system following safety standards as identified in ISO 12100. As further precaution, ISO 13849-1 is used in the design of control systems.
When designing hydraulic systems, it's important to know that every system incorporates a series of fittings and flanges. And because of the need for system maintenance, removable fittings are required in the designing of hydraulic systems, except for certain specialized systems.
Sizing case drain lines. Typically, hydraulic motors and pumps have hoses that run to a case drain in order to drain excess internal oil from the motor. Having a case drain usually requires running motors in series to avoid damage. If the case drain line is undersized on a hydraulic pump (piston) it can cause the pressure in the case to be too high. As the pump’s life depreciates its volumetric efficiency will decrease, which in turn will increase leakage from the case drain line. If there is extreme case pressure it can cause the piston shoe to lift off the swash plate. This will cause damage that will force the pump to stop working. Go by the case drain port size or up-size it. It is important to make sure the case pressure is below the max rating, which if necessary, can be adjusted at the case drain port size, or increase the size of the port. Case pressure can also become too high at:
Selecting the correct inside diameter of fluid piping, such as steel tubing, steel pipes and hydraulic hoses
Piping should be sized to avoid drops in pressure when considering aircraft hydraulic system components. The unstable flow causes unnecessary friction between the walls of the piping and the fluid, ultimately creating lost energy in the system which will raise the temperature of the fluid. This is due to excessive fluid velocity which causes turbulence and unplanned pressure drops. By maintaining a practical fluid velocity, pump inlet conditions will be controlled which will reduce the potential of excessive heat in the aircraft hydraulic system components.
Hydraulic systems in heavy equipment are designed utilizing certain principles for performing work using multiple components. For instance, motors activate pumps; the pumps pressurize hydraulic fluid that passes through tubes to actuators. As an example, the actuators in an excavator move the arm or bucket. The fluid passes through filters, is recycled through the system, and circulates back to the pump.
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