在飞机液压控制系统中，液压保险组件用于监控流过它的流量或容积，正常情况下液压系统的流量低于关断流量，当飞机由于强烈的振动或者受损导致液压保险下游管路破裂或下游负载装置因维修原因拆卸使飞机油液泄露时，导致流过它的流量超过关断流量并持续了额定的时间或者流过的容积超过限定的容积后，液压保险组件将自动关闭油路，防止系统内油液的大量流失，当上游压力解除后，液压保险能够自动回复到初始的状态（有些需要人工复位），从而接通油路。

液压保险的类型为液压流量保险和液压容积保险。

液压流量保险：

1,自动复位。流量限制活门和前缘备用液压保险在龙骨梁上。前缘巡航释压活门和放下收回保险在舱顶。前缘流量限制活门将备用液压流体流量限制在每分钟2.4加仑。当通过的液压流量体积超过180－250 立方英寸时，前缘放下和收上液压保险停止提供液压流体。当通过的液压流量体积超过270－350 立方英寸时，前缘备用液压保险停止液压流动。The flow limiting valve and the LE standby hydraulic fuse are on the keel beam. The LE cruise depressurization valve, and the extend and retract fuses are on the ceiling. The LE flow limiting valve limits the standby hydraulic fluid flow to 2.1 gallons per minute. The LE extend and retract hydraulic fuses stop the hydraulic flow when the volume of fluid through it is more than 180 – 250 cubic inches. The LE standby hydraulic fuse stops the hydraulic flow when the volume of fluid through it is more than 270 – 350 cubic inches.

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2,人工复位。在正常操作过程中，活塞和弹簧处于放松位置。这允许液体压力正常流位计量槽并绕过旁通活门。当流经液压保险的压力差开始下降到低于正常值，活塞开始压缩弹簧。如果 60—95 立方英寸（0.9— 1.5 升）的油液流经液压保险计量槽和旁通活门，活塞压缩弹簧直到液压保险关断。当液压保险的前后压力差下降到0—30 psi之间，液压保险被复位。这使弹簧推动活塞到正常位。复位杆允许将液压保险人工复位。要将液压保险复位，按照液压保险附近铭牌上所示的方向移动复位杆。这操纵液压保险内的旁通活门使液压保险两端压差相等。液压保险没有关断位可视指示。

The brake hydraulic fuses for the normal brake system are on the aft bulkhead of the main landing gear wheel well. The brake hydraulic fuses for the alternate brake system are on the outboard sides of the upper bulkhead of the main landing gear wheel well. During normal operation, the piston and spring are at the relaxed position. This lets fluid pressure go through the metering slot and over the bypass valve normally. When the pressure differential across the fuse starts to decrease below normal, the piston starts to compress the spring. If 60 to 95 cubic inches (0.9-1.5 liters) of fluid goes through the hydraulic fuse metering slot and bypass valve, the piston compresses the spring until the fuse is closed. When the pressure differential across the hydraulic fuse decreases between 0 and 30 psi, the fuse resets. This lets the spring push the piston to the normal position. A reset lever permits manual reset of the hydraulic fuse. To reset the hydraulic fuse, move the reset lever in the direction shown on the placard near the fuse. This operates a bypass valve inside the hydraulic fuse that makes the pressure on each side of the fuse equal. There are no visual indications of a closed fuse.

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液压容积保险（自动复位）：

在反推装置（T／R）控制系统内有3 个容积式液压保险器。如果发生泄漏容积式保险器就关闭和停止液压油流动以防止系统液压油完全流失。备用液压系统供油管至反推装置有两个保险器。到每个反推装置的供油管中有一个保险器。这些保险器是在主轮舱内的下部大梁大。左保险器是在至反推装置1的供油管内。右保险器是在至反推装置2的供油管内。第3个保险器是在至反推装置1的系统A的供油管内。此保险器是在主轮舱前隔框上，在左侧。系统B 在它的至反推装置2的供油管内没有保险器。容积式保险器在它关闭前让约175立方英寸的液压油流过。当保险器两侧的液压大约相同时保险器打开。

There are three volumetric hydraulic fuses in the thrust reverser (T/R) control system.The volumetric fuses close and stop hydraulic fluid flow to prevent a complete loss of system hydraulic fluid if a leak occurs.The standby hydraulic system supply lines to the thrust reversers have two fuses. There is one fuse in the supply line to each T/R. These fuses are on the keel beam in the wheel well. The left fuse is in the supply line to T/R 1. The right fuse is in the supply line to T/R 2. The third fuse is in the system A hydraulic supply line to T/R 1. This fuse is on main gear wheel well forward bulkhead, on the left side. System B does not have a fuse in its supply to T/R 2. A volumetric fuse lets approximately 175 cubic inches of fluid flow through before it closes. The fuse opens when the hydraulic pressure on the two sides of the fuse are approximately the same.

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