China 
Africa 
Explore chapters and articles related to this topic
Risk Control
Published in Derek Viner, Occupational Risk Control, 2016
In mechanical systems, examples of AEC1 or AEC2 include: Overpressure controllers (pressure relief valves). The pressure has risen above normal operating values but a relief valve opens to ensure that the pressure remains below the point at which a structural failure would occur. The reason for the rise in pressure (the Mechanism) has not been influenced in any way by this, it is just being responded to by ensuring that the energy level is brought back into control and so does not reach the point of a damaging Outcome.Rotational speed controllers. A steam turbine can overspeed rapidly with disastrous consequences if the main steam valve opens suddenly or the electrical load on the generator is suddenly lost (Mechanisms). The speed governor operates to stop this happening.
Hydraulic Systems
Published in Anton H. Hehn, Fluid Power Troubleshooting, 1995
Relief valves are devices installed in a circuit to make certain that system pressure does not exceed safety limits. Relief valves are intended to relieve occasional excess pressures arising during the course of normal operation. Excess fluid is allowed to return to the reservoir through an outlet port in the valve while full adjusted pressure is maintained in the system. For safety, the relief valve is usually installed as close as possible to the pump, with no other valving between the relief valve and pump. Relief valves can be divided in two categories: direct-acting and pilot-operated.
On high stiffness of soft robots for compatibility of deformation and function
Published in Advanced Robotics, 2022
Keisuke Hagiwara, Ko Yamamoto, Yoshihisa Shibata, Mitsuo Komagata, Yoshihiko Nakamura
Figure 11 shows the hydraulic system of the developed gripper. This is a closed hydraulic system. The function of each component is summarized as follows: The accumulator keeps the pressure to a certain level and also prevents the cavitation.The check valves open when the pressure becomes lower than a certain level, and let the flow of oil from the accumulator to the hydraulic circuit. They are also opened to charge the oil into the circuit.The relief valve is a safety device to release excessive differential pressure.The charge valve is used for injecting oil from the outside in advance.
Development of 3-DOF wrist mechanism for electro-hydrostatically driven robot arm
Published in Advanced Robotics, 2020
Ryoya Suzuki, Mitsuo Komagata, Tianyi Ko, Kazuya Murotani, Hiroshi Kaminaga, Mamoru Tatano, Ko Yamamoto, Yoshihiko Nakamura
Figure 2 shows the circuit diagram of the developed EHA system. The EHA includes the following elements. Pressure sensors measure the differential pressure in the EHA. It is possible to estimate the external force without using a force sensor.Accumulator prevents cavitation by opening the check valve and applying a preload to the circuit when the pressure in the circuit is below a certain level.Relief valves prevent the pressure from becoming excessive by opening the valve that bypass the connection with the other flow passage when the relative pressure in one flow passage to the other becomes excessive.