562 多用途氣動(dòng)機(jī)器人結(jié)構(gòu)設(shè)計(jì),多用途,氣動(dòng),機(jī)器人,結(jié)構(gòu)設(shè)計(jì) 外文資料翻譯- 1 -Rotary pumps 旋轉(zhuǎn)泵These are built in many different designs and are extremely popular in modern fluid-power system. The most common rotary-pump designs used today are spur-gear, generated-rotary , sliding-vane ,and screw pump ,each type has advantages that make it the most suitable for a given application .旋轉(zhuǎn)泵應(yīng)用于不同的設(shè)計(jì)中，在流體動(dòng)力系統(tǒng)中極其常用。今天最常用的旋轉(zhuǎn)泵是外齒輪泵、內(nèi)齒輪泵、擺線(xiàn)轉(zhuǎn)子泵、滑動(dòng)葉片泵和螺旋泵。每種類(lèi)型的泵都有優(yōu)點(diǎn)，適合于特定場(chǎng)合的應(yīng)用。Spur-gear pumps. these pumps have two mating gears are turned in a closely fitted casing. Rotation of one gear ,the driver causes the second ,or follower gear, to turn . the driving shaft is usually connected to the upper gear of the pump .直齒齒輪泵，這種泵有兩個(gè)嚙合的齒輪在密封殼體內(nèi)轉(zhuǎn)動(dòng)。第一個(gè)齒輪即主動(dòng)輪的回轉(zhuǎn)引起第二個(gè)齒輪即從動(dòng)輪的回轉(zhuǎn)。驅(qū)動(dòng)軸通常連接到泵上面的齒輪上。When the pump is first started ,rotation of gears forces air out the casing and into the discharge pipe. this removal of air from the pump casing produces a partial vacuum on the pump inlet ,here the fluid is trapped between the teeth of the upper and lower gears and the pump casing .continued rotation of the gears forces the fluid out of the pump discharge .當(dāng)泵首次啟動(dòng)時(shí)，齒輪的旋轉(zhuǎn)迫使空氣離開(kāi)殼體進(jìn)入排油管。這種泵內(nèi)空氣運(yùn)動(dòng)使泵吸入口處形成了真空，于是外部油箱的液體在大氣壓的作用下，由泵的入口進(jìn)入，聚集在上下齒輪和泵殼體之間，齒輪連續(xù)的旋轉(zhuǎn)使液體流出泵的出口。Pressure rise in a spur-gear pump is produced by the squeezing action on the fluid ad it is expelled from between the meshing gear teeth and casing ,.a vacuum is formed in the cavity between the teeth ad unmesh, causing more fluid to be drawn into the pump ,a spur-gear pump is a constant-displacement unit ,its discharge is constant at a given shaft speed. the only way the quantity of fluid discharge by a spur-gear pump of type in figure can be regulated is by varying the shaft speed .modern gear pumps used in fluid-power systems develop pressures up to about 外文資料翻譯- 2 -3000psi.直齒齒輪泵的壓力的升高是由擠壓嚙合齒輪和腔體內(nèi)的液體產(chǎn)生的。當(dāng)齒輪脫開(kāi)嚙合時(shí)，腔內(nèi)形成真空，使更多的液體被吸入泵內(nèi)。直齒齒輪泵是定排量的元件，當(dāng)軸轉(zhuǎn)速不變時(shí)，輸出流量恒定。只有一種方法即改變輸入軸的轉(zhuǎn)速，能調(diào)節(jié)這種直齒齒輪泵的排量?，F(xiàn)代應(yīng)用在流體動(dòng)力系統(tǒng)的齒輪泵的壓力可達(dá) 3000psi。Figure shows the typical characteristic curves of a spur-gear rotary pump. These curves show the capacity and power input for a spur-gear pump at various speeds. At any given speed the capacity characteristic is nearly a flat line the slight decrease in capacity with rise in discharge pressure is caused by increased leakage across the gears from the discharge to the suction side of the pump. leakage in gear pumps is sometimes termed slip. Slip also increase with arise pump discharge pressure .the curve showing the relation between pump discharge pressure and pump capacity is often termed the head-capacity or HQ curve .the relation between power input and pump capacity is the power-capacity or PQ curve .圖示為直齒齒輪泵的典型特性曲線(xiàn)。這些曲線(xiàn)表明了泵在不同速度下的流量和輸入功率。當(dāng)速度給定時(shí)，流量曲線(xiàn)接近于一條水平的直線(xiàn)。泵的流量隨出口壓力的升高而稍有降低，這是由于泵的出油口到吸油口的齒輪徑向泄漏所增加而造成的。滲漏有時(shí)定義為泄漏，泵出口壓力的增加也會(huì)使泄漏增加。表征泵的出口壓力和流量之間關(guān)系曲線(xiàn)常叫做水頭流量曲線(xiàn)或泵的 HQ 曲線(xiàn)；泵的輸入功率和泵流量關(guān)系曲線(xiàn)叫做功率流量特性曲線(xiàn)或 PQ 曲線(xiàn)。Power input to a squr-gear pump increases with both the operating speed and discharge pressure .as the speed of a gear pump is increased. Its discharge rate in gallons per minute also rise . thus the horsepower input at a discharge pressure of 120psi is 5hp at 200rpm and about 13hp at 600rpm.the corresponding capacities at these speed and pressure are 40 and 95gpm respectively, read on the 120psi ordinate where it crosses the 200-and 600-rpm HQ curves .直齒齒輪泵的輸入功率隨輸入速度和出口壓力的增加而增加。隨著齒輪泵速度的增加，流量（加侖/分）也增加。于是在出口壓力為 120psi，轉(zhuǎn)速為200rpm 時(shí)，輸入功率是 5 馬力。在轉(zhuǎn)速為 600rpm 時(shí)，輸入功率是 13 馬力?？v外文資料翻譯- 3 -坐標(biāo)壓力是 120psi，橫坐標(biāo)是 200rpm 和 600rpm 時(shí)，在 HQ 曲線(xiàn)上可以讀出相應(yīng)的流量分別為 40gpm 和 95gpm。Figure is based on spur-gear handing a fluid of constant viscosity , as the viscosity of the fluid handle increases (i.e. ,the fluid becomes thicker and has more resistance to flow ),the capacity of a gear pump decreases , thick ,viscous fluids may limit pump capacity t higher speeds because the fluid cannot into the casing rapidly enough fill it completely .figure shows the effect lf increased fluid biscosity on the performance of rotary pump in fluid-power system .at 80-psi discharge pressure the pp has a capacity lf 220gpm when handling fluid of 100SSU viscosity lf 500SSU . the power input to the pump also rises ,as shown by the power characteristics.圖示是直齒齒輪泵在粘度不變時(shí)的情況。隨著流體粘度的增加（即流體變稠，不易流動(dòng)），齒輪泵的流量降低。粘稠的流體在油泵高速運(yùn)轉(zhuǎn)時(shí)，因?yàn)檫@種流體在油泵中不能迅速進(jìn)入泵體完全充滿(mǎn)真空區(qū)，所以油流量受到限制。圖示為在流體動(dòng)力系統(tǒng)中流體粘度的增大對(duì)旋轉(zhuǎn)泵工作情況的影響。當(dāng)流體的粘度值為 100SSU，出口壓力為 80psi 時(shí)，泵流量為 220gpm。當(dāng)流體的粘度值為500SSU 時(shí)，泵流量減少到 150gpm。由功率特性曲線(xiàn)可知，泵輸入功率也會(huì)增加。Capacity lf rotary pump is often expressed in gallons per revolution of the gear or other internal element .if the outlet of a positive-displacement rotary pump is completely closed, the discharge pressure will increase to the point where the pump driving motor stalls or some part of the pump casing or discharge pipe ruptures .because this danger of rupture exists systems are filled with a pressure –relief valve. This relief valve may be built as of the pump or it may be mounted in the discharge piping.可以用齒輪或其他內(nèi)部元件每轉(zhuǎn)一圈輸出多少加侖來(lái)表示泵的流量。如果封閉定量泵的出口，則出口壓力將會(huì)增加，直至驅(qū)動(dòng)馬達(dá)停止或泵內(nèi)其他部分或排油管破裂。由于存在著破裂的危險(xiǎn)，幾乎所有的流體動(dòng)力系統(tǒng)都安裝壓力溢流閥。這種溢流閥可安裝在泵內(nèi)，也可安裝在排油管路。Sliding-Vane Pumps滑動(dòng)式葉片泵These pumps have a number of vanes which are free to slide into or out of slots 外文資料翻譯- 4 -in the pup rotor . when the rotor is turned by the pump driver , centrifugal force , springs , or pressurized fluid causes the vanes to move outward in their slots and bear against the inner bore of the pump casing or against a cam ring . as the rotor revolves , fluid flows in between the vanes when they pass the suction port. This fluid is carried around the pump casing until the discharge port is reached. Here the fluid is forced out of the casing and into the discharge pipe.這些泵有大量的葉片，葉片能在轉(zhuǎn)子的槽內(nèi)自由的滑進(jìn)滑出。當(dāng)驅(qū)動(dòng)轉(zhuǎn)子時(shí)，離心力，彈簧或壓力油使葉片伸出槽子，頂在泵殼體的內(nèi)腔或凸輪環(huán)上。隨著轉(zhuǎn)子的旋轉(zhuǎn)，葉片之間的流體經(jīng)過(guò)吸油口時(shí)，完成吸油。流體順著泵殼體到達(dá)排出口。在排出口，流體被排出，進(jìn)入排油管。In the sliding-vane pump in Figure the vanes in an oval-shaped bore. Centrifugal force starts the vanes out of their slots when the rotor begins turning. The vanes are held out by pressure which is bled into the cavities behind the vanes from a distributing ring at the end of the vane slots. Suction is through two ports A and AI, placed diametrically opposite each other. Two discharge ports are similarly placed. This arrangement of ports keeps the rotor in hydraulic balance, reliving the bearing of heavy loads. When the rotor turns counterclockwise, fluid from the suction pipe comes into ports A and AI is trapped between the vanes, and is carried around and discharged through ports B and BI. Pumps of this design are built for pressures up to 2500 psi. earlier models required staging to attain pressures approximating those currently available in one stage. Valving , uses to equalize flow and pressure loads as rotor sets are operated in series to attain high pressures. Speed of rotation is usually limited to less than 2500rpm because of centrifugal forces and subsequent wear at the contact point of vanes against the cam-ring surface.. 圖示的滑動(dòng)式葉片泵中的葉片安裝在橢圓形的腔內(nèi)。當(dāng)轉(zhuǎn)子開(kāi)始旋轉(zhuǎn)時(shí)，離心力使葉片伸出槽子。同時(shí)葉片又受到其底部腔內(nèi)壓力油的作用力，壓力油來(lái)源于槽子端部的配流盤(pán)。吸油口通過(guò) A 和 A1 口相通，他們位于直徑的相對(duì)位置。同樣兩排油口位于類(lèi)似的位置。油口這樣配置，使葉片轉(zhuǎn)子保持壓力平衡，從而使軸承不受重載影響。當(dāng)轉(zhuǎn)子逆時(shí)針旋轉(zhuǎn)時(shí)，從吸油管出來(lái)的流體進(jìn)入 A和 A1 口，聚集在葉片之間，沿周向流動(dòng)后，通過(guò) B 和 B1 口排出。這樣設(shè)計(jì)的泵壓力可達(dá) 2500psi。的泵必須分級(jí)才能達(dá)到這么大的壓力，而現(xiàn)在用一級(jí)泵外文資料翻譯- 5 -即可達(dá)到。在轉(zhuǎn)子上應(yīng)用均流均壓閥可以達(dá)到高壓。轉(zhuǎn)速通常限制在 2500rpm這是因?yàn)榭紤]到離心力和凸輪環(huán)表面葉片之間的磨損。圖示為泵在轉(zhuǎn)速為1200rpm 粘度在 100F 的條件下的特性曲線(xiàn)。Two vanes may be used in each slot to control the force against the interior of the casing or the cam ring. Dual vanes also provide a tighter seal , reducing the leakage from the discharge side to the suction side of the pump . the opposed inlet and discharge port in this design provide hydraulic balance in the same way as the pump, both these pumps are constant-displacement units.每個(gè)槽內(nèi)安裝兩個(gè)葉片可以控制其作用于殼體內(nèi)部和凸輪環(huán)上的力。雙葉片會(huì)產(chǎn)生更緊的密封，能減少?gòu)呐庞涂诘轿涂谥g的泄漏這種入口和出口相對(duì)應(yīng)的設(shè)計(jì)也能維持液壓平衡。這些都是定量泵。The delivery or capacity of a vane-type pump in gallons per minute cannot be changed without changing the speed of rotation unless a special design is used. Figure shows a variable-capacity sliding-vane pump. It dose not use dual suction and discharge ports. The rotor rums in the pressure-chamber ring, which can be adjusted so that it is off-center to the rotor. As the degree of off-center or eccentricity is changed, a variable volume of fluid is discharged. Figure shows that the vanes create a vacuum so that oil enters through 180 of shaft rotation. Discharge also takes place through 180 of rotation. There is a slight overlapping of the beginning of the fluid intake function and the beginning of the fluid discharge.不改變轉(zhuǎn)速就不能改變?nèi)~片泵的流量，除非油泵采用特殊設(shè)計(jì)。圖示為滑動(dòng)式變量葉片泵。它不用雙吸油和排油口。轉(zhuǎn)子在壓力腔內(nèi)轉(zhuǎn)動(dòng)，轉(zhuǎn)子形成的偏心量是可調(diào)的。隨著偏心的程度或偏心率的變化，流體的流量也隨著變化。圖示為轉(zhuǎn)子在旋轉(zhuǎn) 180°范圍內(nèi)，產(chǎn)生一真空度以便于油液進(jìn)入，同時(shí)壓油區(qū)也在 180°范圍內(nèi)旋轉(zhuǎn)。吸油區(qū)和壓油區(qū)的起始段梢有重疊。Figure shows how maximum flow is available at minimum working pressure. As the pressure rises, flow diminishes in a predetermined pattern. As the flow decreases to a minimum valve, the pressure increases to the maximum. The pump delivers only that fluid needed to replace clearance floes resulting from the usual slide fit in circuit components.外文資料翻譯- 6 -圖示，在最小的工作壓力下可以得到最大的流量。隨著壓力的升高，流量按預(yù)設(shè)的規(guī)律減少。當(dāng)流量減到最小值，壓力增大到最大值。泵只需要提供補(bǔ)充回路中元件滑動(dòng)配合間隙中泄漏流體。A relief valve is not essential with a variable-displacement-type pump of this design to protect pumping mechanism. Other conditions within the circuit may dictate the use of a safety or relief valve to prevent localized pressure buildup beyond the usual working levels.這種變量泵的設(shè)計(jì)可以保護(hù)管路，溢流閥不是必須的。其他回路中，為阻止局部壓力超過(guò)正常壓力水平，可以用安全閥或溢流閥來(lái)控制。For automatic control of the discharge , an adjustable spring-loaded governor is used . this governor is arranged so that the pump discharge acts on a piston or inner surface of the ring whose movement is opposed by the spring . if the pump discharge pressure rises above that for which the by governor spring is set , the spring is compressed. This allows the pressure-chamber ring to move and take a position that is less off center with respect to the rotor. The pump theb delivers less fluid, and the pressure is established at the desired level. The discharge pressure for units of this design varies between 100 and 2500psi.為了自動(dòng)控制流量，采用可變彈簧負(fù)載調(diào)節(jié)器。安裝這種調(diào)節(jié)器，泵的出口壓力作用于活塞或定子內(nèi)表面，壓縮的彈簧產(chǎn)生位移。如果泵的出口壓力高于調(diào)節(jié)器彈簧的設(shè)定值時(shí)，彈簧被壓縮。這使壓力環(huán)（定子）移動(dòng)，減少相對(duì)于定子的偏心量，于是，泵的流量減少，得到所需的壓力。這種油泵設(shè)計(jì)的出口壓力在 100psi 和 2500psi 之間。The characteristics of a variable-displacement-pump compensator are shown in figure. Horsepower input values also shown so that the power input requirements can be accurately computed. Variable-volume vane pumps are capacity of multiple-pressure levels in a predetermined pattern. Two-pressure pump controls can provide an efficient method of unloading a circuit and still hold sufficient pressure available for pilot circuits.圖示為變量泵補(bǔ)償器的特性，標(biāo)出輸入功率值，可以準(zhǔn)確計(jì)算所需的輸入功率。變量泵可以預(yù)先設(shè)定不同壓力值的變化規(guī)律。高低壓泵控制既能提供有效的卸荷回路，也能為先導(dǎo)控制回路提供足夠壓力。外文資料翻譯- 7 -The black area of the graph of figure shows a variable-volume pump maintaining a pressure of 100psi against a closed circuit. Wasted power is the result of pumping oil at 100psi through an unloading or relief valve to maintain a source of positive pilot pressure. Two-pressure –type controls include hydraulic, pilot-operated types and solenoid-controlled, pilot-operated types. The pilot oil obtained from the pump discharge cannot assist the governor spring. Minimum pressure will result. The plus figure shows the solenoid energized so that pilot oil assists compensator spring. The amount of assistance is determined by the small ball and spring, acting as a simple relief valve. This provides the predetermined maximum operating pressure.圖示陰影區(qū)域?yàn)樽兞勘迷诒硥?100psi 壓力下的閉式回路。油液以 100psi卸荷閥或溢流閥排出，可以維持正常的控制回路壓力，這些是消耗的功率。兩級(jí)壓力控制回路包括：先導(dǎo)液壓控制和電磁控制。圖示負(fù)號(hào)表示電磁鐵不帶電，先導(dǎo)控制油回油箱。于是泵排出的控制油的力小于調(diào)節(jié)器彈簧力，所以得到最小壓力。圖示正號(hào)為電磁鐵帶電，控制油的力大于調(diào)節(jié)器彈簧力。與簡(jiǎn)單的溢流閥原理一樣，小球和彈簧決定控制力的大小。這樣預(yù)先設(shè)定最大工作壓力。Another type of two-pressure system employs what is termed a differential unloading governor. It is applied in a high-low or two-pump circuit. The governor automatically, Through pressure sensing, unloads the large volume pump to a minimum deadhead pressure setting. Deadhead pressure refers to a specific pressure level established as resulting action of the variable-displacement-pump control mechanism. The pumping action and the resulting flow at deadhead condition are equal to the leakage in the system and pilot-control flow requirements. No major power movement occurs at this time, even though the hydraulic system may be providing a clamping or holding action while the pump is in deadhead position 另一種兩級(jí)壓力控制系統(tǒng)是利用所謂的差動(dòng)卸荷調(diào)節(jié)器。它應(yīng)用于高低壓或雙泵回路中。調(diào)節(jié)器通過(guò)壓力傳感器自動(dòng)卸荷大流量泵以達(dá)到最小的空載壓力設(shè)定值?？蛰d壓力指的是由于變量泵控制機(jī)構(gòu)工作所形成的特定壓力。泵的實(shí)際空載流量等于系統(tǒng)的泄漏量與控制流量之和。當(dāng)泵空載時(shí)，即使液壓系統(tǒng)在提供加緊或保壓作用，也不會(huì)需要較大的功率。The governor is basically a hydraulically operated, two-pressure control with a differential piston that allows complete unloading when sufficient external pilot 外文資料翻譯- 8 -pressure is applied to pilot unload port.調(diào)節(jié)器是液壓操縱的，差動(dòng)活塞帶有雙壓力控制，當(dāng)外部控制壓力作用于控制卸荷口時(shí)，差動(dòng)活塞允許完全卸荷。The minimum deadhead pressure setting is controlled by the main governor spring A. the maximum pressure is controlled by the relief-valve adjustment B. the operating pressure for the governor is generated by the large-volume pump and enters through orifice C. 空載壓力的最小設(shè)定值由調(diào)節(jié)器主彈簧 A 控制。最大壓力由溢流閥調(diào)節(jié)點(diǎn)B 控制。調(diào)節(jié)器的操作壓力由大容積泵提供，從小孔 C 進(jìn)入。To use this device let us assume that the circuit require a maximum pressure of 1000psi, which will be supplied by a 5-gpm pump. It also needs a large flow (40gpm) at pressure up to 500psi; it continues to 1000pso at the reduced flow rate. A two-pump system with an unloading governor on the 40-gpm pump at 500psi to a minimum pressure setting of 200psi (or another desired value) , which the 5-gpm pump takes the circuit up to1000psi or more.為了說(shuō)明如何使用這種裝置，假設(shè)回路需要 1000psi 的最大壓力，由一個(gè) 5-gpm 來(lái)提供。在壓力達(dá)到 500psi 時(shí)，需要大流量（40gpm），繼續(xù)上升到1000psi，流量減少。由流量為 40-gpm 的帶有卸荷調(diào)節(jié)器的泵組成的雙泵系統(tǒng)可滿(mǎn)足要求。我們可以把 40-gpm 的泵從 500psi 卸荷壓力調(diào)整至 200psi 最小設(shè)定壓力（或另一需求值），這樣 5-gpm 泵可以使回路達(dá)到 1000psi 或更高壓力。Note in figure that two sources of pilot pressure are required. One ,the 40-gpm pump, provides pressure within the housing so that maximum pressure setting can be obtained. The setting of the spring, plus the pressure within the governor housing, determines the maximum pressure capacity of the 40-gpm pump. The second pilot source is the circuit proper, which will go to 1000psi. this pilot line enters the governor through orifice D and acts on the unloading piston E . the area of piston E is 15 percent greater than the effective area of the relief poppet F. the governor will unload at 500psi and be activated at 15percent below 500psi, or 425psi. By unloading, we mean zero flow output of the 40-gpm pump.外文資料翻譯- 9 -圖中為雙泵系統(tǒng)控制壓力源。由一個(gè) 40-gpm 的泵提供調(diào)節(jié)器腔內(nèi)壓力，就可以達(dá)到最大設(shè)定壓力。彈簧設(shè)定力加上調(diào)節(jié)器的腔內(nèi)壓力共同決定了 40-gpm泵的最大壓力。第二個(gè)控制源是特殊的回路，它能達(dá)到 1000psi?？刂朴屯ㄟ^(guò)小孔 D 進(jìn)入調(diào)節(jié)器作用于卸荷活塞 E。活塞 E 面積比安全閥中提動(dòng)閥 F 的有效面積大 15％。因此卸荷差動(dòng)力大約為 15％。調(diào)節(jié)器將在 500psi 卸荷，會(huì)在500psi 以下 15％或 425psi 時(shí)起作用。這里所謂的卸荷，指的是 40-gpm 的泵無(wú)輸出量。As pressure in the circuit increases from zero to 500psi, the pressure within the governor housing also increases until the relief-valve setting is reached, at which time the relief valve cracks open, allowing flow to the tank.隨著回路中壓力從 0 到 500psi 的增加，調(diào)節(jié)器腔內(nèi)的壓力也隨著增加，直到溢流閥的設(shè)定值時(shí)，溢流閥打開(kāi)，流體流出油箱。The pressure drop in the hosing is a maximum additive value, allowing the pump to deadhead. Meanwhile, the system pressure continues to rise above 700psi, resulting in a greater force on the bottom of piston E than on the top. The piston then completely unseats poppet F, which results in a further pressure drop within the governor horsing to zero pressure because of the full-open position of the relief poppet F. flow entering the housing through orifice is directed to the tank pass the relief poppet without increasing the pressure in housing. The deadhead pressure of the 40-gpm pump then decreases to the lower set value. Thus , at the flow rate to the unloading governor ,the 40gpm pump goes to deadhead. The flow rate to the circuit decreases to 5gpm as the pressure to 1000psi, the 5-gpm pump is also at its deadhead setting, thus only holding system pressure.The 4-gpm pump unloads its volume at 500psi. It requires a system pressure of 600psi to unload the 40-gpm pump to its minimum pressure of 200psi. the 600-psi pilot supply enters through orifice D and acts on the differential piston E. The pumps volume is reduced to zero circuit-flow output at 500psi. The additional 100-psi pilot pressure is required to open poppet F completely and allow the pressure within the housing to decrease to zero.As circuit pressure decreases ,both pumps come back into service in a similar pattern.調(diào)節(jié)器腔內(nèi)的壓力降是最大的疊加值，允許油泵達(dá)到卸荷狀態(tài)。同時(shí)，當(dāng)系統(tǒng)壓力繼續(xù)增加超過(guò) 700psi 時(shí)，導(dǎo)致活塞 E 最底部的壓力比頂部的壓力大。外文資料翻譯- 10 -活塞使提升閥 F 完全打開(kāi)，溢流提升閥全部開(kāi)啟導(dǎo)致調(diào)節(jié)器腔內(nèi)壓力進(jìn)一步下降至零。流體通過(guò)小孔 C 進(jìn)入調(diào)節(jié)器腔，經(jīng)過(guò)溢流提升閥直接回油箱，不增加調(diào)節(jié)器腔內(nèi)的壓力。40-gpm 的泵卸荷壓力可以減小至更低的設(shè)定值。調(diào)整卸荷調(diào)節(jié)器，40-gpm 的泵達(dá)到卸荷。隨著壓力到 1000psi，回路的流量減至 5gpm。在 1000psi 時(shí)，5-gpm 泵也達(dá)到卸荷設(shè)定，于是流量?jī)H僅維持系統(tǒng)壓力。在500psi 時(shí)，40-gpm 的油泵卸荷。需要 600psi 的系統(tǒng)壓力把 40gpm 的泵卸荷到最小壓力 200psi。600psi 的先導(dǎo)控制油通過(guò)孔 D 進(jìn)入并作用于差動(dòng)活塞 E。在500psi 時(shí)，泵流量減少到零。100psi 的附加壓力需要完全打開(kāi)提升閥，使調(diào)節(jié)器腔內(nèi)的壓力減小至零。當(dāng)回路壓力減小時(shí)，兩個(gè)泵以同樣的方式來(lái)工作。