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时间:2011-03-30 23:21来源:蓝天飞行翻译 作者:航空
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B.  Lift Actuator
(1)  The lift actuator is hydraulically operated. The actuator is composed of a cylinder assembly and a piston assembly which incorporates a ram lock assembly. The piston assembly is driven when hydraulic pressure is applied to an "open" or "close" port on each end of the actuator. If hydraulic pressure is lost and if the main cargo door is in the canopy position, an internal mechanical ram lock locks the actuator. The door may be lowered below the canopy position and ram lock position after hydraulic pressure applied to the "close" line is sensed by a pressure differential assembly of the ram lock assembly. The pressure differential assembly releases the ram lock and allows the cargo door to be lowered when a pressure differential of 300 to 900 psi is present. The rate that the cargo door closes in the event of hydraulic line rupture is controlled by a restrictor in the "open" port of the actuator. A spring retained felt ring on the outboard end of the actuator absorbs any hydraulic fluid which may leak past the piston rod seal.
517 
Aug 15/72  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  52-32-0 Page 9 


Main Cargo Door Locking Mechanism  511 
52-32-0  Figure 3 (Sheet 1)  May 15/68 
Page 10 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 


517  Main Cargo Door Locking Mechanism 
Jan 15/71  Figure 3 (Sheet 2)  52-32-0 
Page 11 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 


Main Cargo Door Lift Mechanism  511 
52-32-0  Figure 4  Aug 15/72 
Page 12 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 


511  Main Cargo Door Lift Actuator 
Aug 15/72  Figure 4A  52-32-0 
Page 12A/12B 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 


5.  Control Panel
A.  The main cargo door control panel is on the left side of the forward bulkhead of the passenger compartment. The panel contains two main cargo door control switches, and amber control light (Ref par. 1) and lighting switches (Ref Chapter 33) (Fig. 5).
B.  The two main cargo door switches are three position switches which are spring loaded to a center (OFF) position. The left switch is referred to as switch No. 1; the right switch is referred to as switch No. 2. The two switches must be operated in sequence to raise the cargo door to the full open position or lower it from the full open position. Switch No. 1 is held in the UP TO CANOPY position to unlatch and raise the door to the canopy position. The door will automatically stop when the canopy position (approximately 87 degrees) is reached. Holding switch No. 1 to CLOSE causes the door to close and latch from the canopy position. Switch No. 2 is used to raise the door above the canopy position and to lower the door to the canopy position when positioned to FULL OPEN or DOWN TO CANOPY respectively. Releasing a control switch while the door is in transit causes the door to hydraulically lock in the interim position. If the switch is operated again, the door will continue to raise or lower, depending on the position of the switch.
6.  Handpump
A.  A handpump and handle are installed on the left wheel well aft bulkhead. The handpump is a single piston type which can be used to supply hydraulic pressure to the cargo door is system B pressure is not available. The pump has two ports, supply and pressure, and a sleeve for installation of a removable handle. The pump may be operated after removing the handle from its stowage rack, inserting the handle into a sleeve on the pump and rotating the handle a half turn to engage the slots of the handle over a retaining bolt in the sleeve. Approximately 40 strokes of the pump will raise the cargo door to the canopy position. Approximately 25 additional strokes are needed to raise the door to the full open position.
520 
Feb 01/76  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  52-32-0 Page 13 


Main Cargo Door Control Panel  511 
52-32-0  Figure 5  May 15/68 
Page 14 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 


7.  Control Valve
A.  The control valve is installed on the left wheel well aft bulkhead. The valve is motor driven, has four ports and a manual override lever. The valve has two internal double pole switches which are operated whenever the valve is ported to "door open" or "door closed" positions. These positions are marked Position No. 1 and Position No. 2, respectively on the valve. The switches the motor to drive the valve to position 1 or position 2, depending on the last position of the internal switches. When the valve moves to one extreme position, the switch connected to the driven winding is opened, thus automatically stopping the motor, and the switch connected to the second winding was closed when the valve left the other extreme position. The motor uses 28-volt dc power.
 
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