G.
Flow Control Valve
__________________
(1)
The flow control valve is a pressure-operated, two-position, in-line valve. It controls hydraulic fluid flow to and from the extend pressure side of the door actuator. The valve also limits fluid flow to return from the door actuator when the landing gear is down and locked and the doors are not fully closed. This function slows the speed at which the door close. This is for safety when the landing gear doors are opened or closed for ground maintenance. At all other times, the fluid flow is not limited.
(2)
The flow control valve is installed in the hydraulic lines in the wheel well for the nose landing gear.
Gear-Operated Sequence Valve
Figure 3
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SEE A
ACTUATOR DOOR VALVE CONTROL FLOW
SEQUENCE VALVE DOOR-OPERATED
FORWARD DOORS
A
Door-Operated Sequence Valve, Door Actuator, and Flow Control Valve
Figure 4
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Gear Sequence Valve Bypass Valve
Figure 5
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H. GUN 206;
Restrictor Check Valve & Pressure Operated Check Valve
______________________________________________________
(1)
The pressure-operated check valve is a two position valve. When there is pressure in the Down line the pressure-operated check valve is positioned to permit flow from the rod end to the head end of the actuator. The increased extension rate of the actuator is controlled by the restrictor check valve in the Up line to the retract actuator. When there is no pressure in the Down line, flow between the rod end and the head end of the actuator is blocked.
(2)
The restrictor check valve limits flow from the rod end of the actuator when the nose landing gear is extends. This assures smooth extension of the nose landing gear.
(3)
The restrictor check valve is installed on the rod end of the retract actuator. The pressure-operated check valve is installed in the hydraulic lines in the wheel well for the nose landing gear.
3. Operation (Fig. 6)
_________
A. Functional Description
(1)
Landing Gear Retraction
(a)
Hydraulic pressure changes the position of the flow control valve. This permits the flow of fluid to and from the door actuator with no limit.
(b)
Hydraulic fluid flows through the gear-operated sequence valve and the flow control valve. This pressurizes the door actuator to extend and the doors start to open.
(c)
Before the doors are fully open, hydraulic fluid pressurizes the lock actuator to retract. The lock actuator pulls the lock links from the overcenter position and releases the landing gear from the down and locked position.
(d)
When the doors are almost fully open, hydraulic fluid flows through the door-operated sequence valve and the gear sequence valve bypass valve to pressurize the retract actuator. The retract actuator retracts to retract the nose landing gear forward and up into the wheel well.
(e)
While the gear retracts, the gear-operated sequence valve keeps pressure on the door actuator to make sure that the doors stay open. During gear retraction, movement of the lock link causes the lock actuator to extend. Hydraulic pressure is still applied to retract the actuator but this does not prevent lock actuator extension.
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HYDRAULIC POWERLEFT HYDRAULIC
TRANSFER UNIT SYSTEM POWER
DOWN
UP
OFF
LANDING GEAR
SELECTOR VALVE
TO MAIN LANDING
GEAR SYSTEMS DOWN DURING GEAR MOVEMENT UP
1 2 2 3
NOSE LANDING GEAR GEAR-OPERATEDSEQUENCE VALVENOSE LANDING GEAR DOOR-OPERATED SEQUENCE VALVE
LOCK UNLOADVALVE MODULE DOORSAFETYVALVE FLOW CONTROL VALVEUNLOCK
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本文链接地址：757 AMM 飞机维护手册 起落架 CHAPTER 32 - LANDING GEAR 2(75)
