Simple Solutions That Work! Issue 6

According to OSHA, hydraulics and electricity are both methods of transmitting and storing energy. In many cases hydraulics is comparable to electricity in regards to operator risk level and operator safety procedures. Analogies between hydraulics and electric: The molecules of fluid in a hydraulic circuit behave much like the electrons in an electrical circuit. It is important that the foundry maintenance manager understand the analogies between pressure and voltage and between ground and the hydraulic reservoir. When a valve shifts to power a hydraulic actuator, the actuator does not react instantaneously, but shortly after the valve is shifted. This is because the molecules within the actuator start moving with a time delay governed by the speed of sound and the physical dimensions of the circuit. On the other hand, an individual molecule of fluid inside the pump when the valve shifts may require seconds, before it actually passes through the actuator — well after the actuator started moving. Similarly, it can take minutes, or even hours, before an individual electron inside a generator makes its way into a load, such as an electric motor. Yet, the electric motor reacts to the closing of a switch with a time delay that is governed by the speed of light. These concepts are useful because they lead to an understanding of why electronic and hydraulic devices do not always appear to react instantaneously. Pressure is what drives the movement of fluid molecules from a region of high pressure to a region of lower pressure. The hydraulic pump SYSTEMS INTEGRATION JOHN HALL President CMH MANUFACTURING COMPANY ARTICLE TAKEAWAYS: 1. Understanding analogies between pressure & voltage 2. The term “ground” has evolved and means any common point in a circuit to which all circuits return raises the energy content of the fluid in the form of elevated pressure, and the higher pressure at the pump sends energized fluid into the load to do useful work (move ram or tilt machine). The fluid particles experience ever- diminishing pressure as they make their way around the circuit and ultimately back to the reservoir. Voltage is analogous to pressure, and it is what drives the electrons to migrate from regions of high voltage to regions of low voltage. Ground is a term that can lead to confusion because of the way it is used, especially in electronic control systems. The term ground derives from the fact that mother Earth is used as a conductor by the electrical power industry. In the wiring of your house, for example, electrical codes require that part of your house wiring (the green wire) must be connected to mother Earth. That wire eventually leads to a stake driven into mother Earth or a physical connection to a water pipe that is buried underground. The term ground has evolved into one that means any common point in a circuit to which all circuits return, which may not necessarily be mother Earth. The ground is similar to how the reservoir is connected in the hydraulic circuit. Ground and reservoir are analogous terms. We could define the reservoir as that point in the circuit to which 12 HYDRAULIC SAFETY in Permanent Mold Casting Machines