【正文】 ign principles. A slotted rotor is coupled to the drive shaft and turns inside of a cam ring that is offset or eccentric to the drive shaft. Vanes are inserted into the rotor slots and follow the inner surface of the cam ring as the rotor turns. The vanes and the inner surface of the cam rings are always in contact and are subject to high amounts of wear. As the two surfaces wear, the vanes e further out of their slot. Vane pumps deliver a steady flow at a high cost. Vane pumps operate at a normal viscosity range between 14 and 160 cSt at operating temperature. Vane pumps may not be suitable in critical highpressure hydraulic systems where contamination and fluid quality are difficult to control. The performance of the fluid’s antiwar additive is generally very important with vane pumps. Piston Pumps As with all hydraulic pumps, piston pumps are available in fixed and variable displacement designs. Piston pumps are generally the most versatile and rugged pump type and offer a range of options for any type of system. Piston pumps can operate at pressures beyond 6000 psi, are highly efficient and produce paratively little noise. Many designs of piston pumps also tend to resist wear better than other pump types. Piston pumps operate at a normal fluid viscosity range of 10 to 160 cSt. Gear Pumps There are two mon types of gear pumps, internal and external. Each type has a variety of subtypes, but all of them develop flow by carrying fluid between the teeth of a meshing gear set. While generally less efficient than vane and piston pumps, gear pumps are often more tolerant of fluid contamination. 1. Internal gear pumps produce pressures up to 3000 to 3500 psi. These types of pumps offer a wide viscosity range up to 2200 cSt, depending on flow rate and are generally quiet. Internal gear pumps also have a high efficiency even at low fluid viscosity. 2. External gear pumps are mon and can handle pressures up to 3000 to 3500 psi. These gear pumps offer an inexpensive, midpressure, midvolume, fixed displacement delivery to a system. Viscosity ranges for these types of pumps are limited to less than 300 cSt. Hydraulic Fluids Today’s hydraulic fluids serve multiple purposes. The major function of a hydraulic fluid is to provide energy transmission through the system which enables work and motion to be acplished. Hydraulic fluids are also responsible for lubrication, heat transfer and contamination control. When selecting a lubricant, consider the viscosity, seal patibility, base stock and the additive package. Three mon varieties of hydraulic fluids found on the market today are petroleumbased, waterbased and synthetics. 1. Petroleumbased or mineralbased fluids are the most widely used fluids today. The properties of a mineralbased fluid depend on the additives used, the quality of the original crude oil and the refining process. Additives in a mineralbased fluid offer a range of specific performance characteristics. Common hydraulic fluid additives include rust and oxidation inhibitors (Ramp。 圖 3 粘度 溫度表 此外， 請遵守以下液壓 油的管理 原則 : (1) 標記所有的輸入液壓油和液壓油箱 。接著從此交點引一條垂直線（圖 3 中綠線）至表底部。 (5) 結合第三步研究潤滑油粘度特性所得到的結論，首先在圖表的溫度軸 （ x軸）上找出溫度所對應的線如 40 186。這里推薦使用國際標準化組織粘度評級系統(tǒng)（適用于 40186。這其中包括泵在設計中的局限性和其出廠時所規(guī)定的最佳工作條件。氧化時液壓油的壽命大大降低，而且會產(chǎn)生諸如污泥和清漆之類的副產(chǎn)品。與低粘度的液壓油相比，高粘度的液壓油在流動時會受到更大的阻力。水基液壓油的價 格比常規(guī)的石油基液壓油高，而且它還有一些其它缺點（例如，較低的耐磨性），因此在使用時需權衡利弊?？傮w上來說，礦物液壓油的性價比很高， 是非常好的選擇。同時，液壓油還 擔負著潤滑、散熱、防污的重任。 (1) 內嚙合式齒輪液壓泵所能產(chǎn)生的壓力高達 3000 至 3500 帕斯卡。 柱塞泵 和所有的液壓泵相同，柱塞泵也被設計為定量泵和變量泵兩種。 3 液壓 系統(tǒng) 潤滑 的重點 組件 考慮到維修成本和任務的重要程度，液壓系統(tǒng)的各組成元件中，泵和閥門是關鍵組成部分。液壓泵有齒輪泵，葉片泵，柱塞泵幾種類型。液壓幫助操作員完成許多重要工作 (抬沉 重的負荷、轉向軸、孔鉆進精度等 )，同時有效降低了機械聯(lián)動的成本，這一切都歸功于帕斯卡定律，帕斯卡定律表述如下： “ 由于液體的流動性，封閉容器中的靜止流體的某一部分發(fā)生的壓強變化，將毫無損失地傳遞至流體的各個部分和容器壁 （圖 1） 。 1795 年，他申請并獲得了液壓機的相關專利，從此 布拉瑪 液壓機聲名鵲起。 2 液壓 系統(tǒng)的組成 液壓系統(tǒng)的主要組成部分是液壓缸，液壓泵，閥和執(zhí)行機構（馬達，油缸等）。 執(zhí)行機構 液壓執(zhí)行機構是帕斯卡定律的終端，它的目的是將