【正文】 s was seen in a worker who touched a lot of hydraulic fluids. Rabbits that inhaled very high levels of one type of hydraulic fluid had trouble breathing, congested lungs, and became drowsy. The nervous systems of animals that swallowed or inhaled other hydraulic fluids were affected immediately with tremors, diarrhea, sweating, breathing difficulty, and sometimes several weeks later with weakness of the limbs, or paralysis. The immediate effects are caused because hydraulic fluids stop the action of certain enzymes, called cholinesterases, in the body. There are no reports of people swallowing or breathing the types of hydraulic fluids that cause these effects. When certain types of hydraulic fluids were put into the eyes of animals or allowed to touch the skin of people or animals for short periods of time, redness and swelling occurred. It is not known whether hydraulic fluids can cause birth defects or reproductive effects. Is there a medical test to show whether I39。t be measured in blood, urine, or feces, but certain chemicals in the hydraulic fluids can be measured. Some of the hydraulic fluids stop the activity of certain enzymes, called cholinesterases, in blood and this activity can be measured. However, many other chemicals also cause this effect. This test isn39。 offices, but can be done at special laboratories that have the right equipment. Has the federal government made remendations to protect human health? There are no federal government remendations to protect humans from the health effects of the major hydraulic fluids. However, mineral oil, the major chemical ingredient of one type of hydraulic fluid, is part of the petroleum distillate class of chemicals and there are regulations for these chemicals. The Occupational Safety and Health Administration (OSHA) has set an exposure limit of 2,000 milligram per cubic meter (mg/mamp。) petroleum distillates for an 8hour workday, 40hour workweek. The National Institute for Occupational Safety and Health (NIOSH) remends an exposure limit of 350 mg/mamp。 petroleum distillates for a 10hour workday, 40hour workweek. Hydraulic technology has been the introduction of industry have a history of more than one hundred years. With the rapid development of industrial, hydraulic technology with each passing day. Along with mathematics, control theory, puters, electronic devices and the development of fluid mechanics, a hydraulic servo system. And as an applied science that has e of age, and form their own system and a wellestablished methods of analysis and design. The following is a method of hydraulic system design and attention to the problem: The based of Hydraulic design of hydraulic drive system The overall layout of the hydraulic machine and process requirements, including the use of hydraulic transmission by the type of machine, mechanical design made possible the implementation of the hydraulic ponents of the type and model, the implementation of ponents and their spatial position of the size range, the requirements of the degree of automation. The work of the hydraulic machine cycle, the executing agency of the movement, as well as the scope of work pleted.① Hydraulic velocity ponents, speed reference, travel, changes in the nature and scope of the load. ② The order of the parts and the interlocking action, as well as the work of the various ponents, such as the environment and area. ③ Hydraulic system performance, such as stability, reliability, accuracy for the duration of time and out of traffic and other requirements. Other requirements, such as the quality of the hydraulic device, and economic dimensions, and so on 3, relief valve instability, such as slidevalve as a result of mismatch with the valve hole or conical valve contact with the valve seat is to be dirt stuck, damping plug holes, springs, etc. skew or failure in the valve spool jammed or hole Mobile not working, causing the system pressure fluctuations and noise. In this regard, should pay attention to cleansing, to clear the hole damping。 4, valve adjusted properly, so that spool valve moving too fast, resulting in reversing the impact, resulting in noise and vibration. In this case, if the valve is a hydraulic valve, it should adjust the control circuit ponents of expenditure, so that the impact of exchange to nonsmooth. At work, hydraulic spool valve support spring, when the oil pump frequency and the pulse rate frequency or with other similar local oscillator frequency will cause vibration, noise. At this time, by changing the natural frequency of the pipeline system, change the location of control valves to increase storage or appropriate, you can vibration noise. 5, mechanical vibration, such as thin tubing, and more without additional fixed bend in the flow of oil out of date, especially when a higher flow rate, it is easy to jitter caused by the tube。 adjustment of the hydraulic pump motor and the installation of precision