737 AMM 飞机维护手册 起落架 LANDING GEAR(21)

曝光台 注意防骗 网曝天猫店富美金盛家居专营店坑蒙拐骗欺诈消费者

B.  The outer cylinder is a single piece forging, bored to fit the inner cylinder. The upper portion provides an extension for attachment to airplane structure. (See figure 2.) A full shock strut width lug on the opposite side, provides an attachment for the trunnion link. Lugs on the lower end provide attachment points for drag strut, torsion links and universal side strut attachment. The orifice support tube projects through the top of the outer cylinder where it is secured by a nut. A charging valve is installed in the top of the orifice support tube.
C.  The inner cylinder, with all lugs and the axle, including brake flanges, is machined from one forging. A diaphragm integral with the metering pin seals off the inside bore of the inner cylinder. A drain tube attached to the metering pin is secured by a nut to the underside of the inner cylinder. A check valve is installed at the bottom of the cylinder for strut servicing. In addition to axles, the lower end of the cylinder has a towing lug and a jacking pad.
D.  A snubber valve is installed on the inner cylinder, just below the upper bearing. The valve consists of an angular sectioned bronze ring moving up and down when the shock strut operates, to act as a one way restrictor. When the shock strut is compressing, the snubber valve allows an unrestricted flow of oil from the upper chamber into the annular space between inner and outer cylinders. When the shock strut extends, the snubber valve moves up to close off holes in the upper bearing; this restricts flow from the annular space and so absorbs shock strut rebound.
E.  With the shock strut compressed and serviced with oil, the outer cylinder contains oil all around the piston rod and in the space between inner and outer cylinders. The shock strut is then inflated with nitrogen or air to the specified pressure.
504 
32-11-0 Page 2  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Feb 15/72 

500  Main Gear Components Location 
Feb 20/91  Figure 1  32-11-0 
Page 3 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

 

E.  Shocks are absorbed by the flow of hydraulic fluid through the annular space between the orifice and the tapered metering pin. As the shock strut is compressed, oil flows through the orifice and the movement of the tapered metering pin through the orifice progressively varies the area of the annular space between orifice and pin. The variation in area results in an adjusted rate of hydraulic flow from the inner cylinder chamber to the upper side of the piston, thus providing uniform control of the impact loads on the airplane structure when landing. Landing and taxi shocks are also cushioned by the increasing volume of hydraulic fluid above the piston further compressing the volume of compressed air or nitrogen in the upper end of the outer cylinder. As the shock strut extends, there is a reversal of flow through the orifice. The hydraulic fluid now being forced from the upper to the lower side of the piston must pass through the space around the metering pin, and through holes in the orifice support tube. Also, fluid in the annular space between the inner and outer cylinders is forced through the snubber valve restriction, and through the upper bearing into the upper chamber. The resulting resistance to hydraulic flow dampens the return movement of the shock strut.
4.  Main Gear Drag Strut
A.  The main gear drag strut stabilizes the shock strut in a fore and aft direction. The drag strut is in two parts. The upper drag strut is attached to a lug on the trunnion link at the top end, and to the lower drag strut at the bottom end. The lower drag strut is connected to the upper torsion link lugs on the outer cylinder, and to the side strut universal attachment on the shock strut  (Fig. 1). A special shear bolt is used for the upper attachment to minimize damage to structure should landing gear receive a severe impact from the front. Clamps and attachments on the drag strut support linkage for the shock strut door.
500 
32-11-0 Page 4  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Aug 01/74 

500  Main Gear Attachment 
Feb 20/91  Figure 2 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  32-11-0 Page 5 

Main Gear Shock Strut Schematic  551 
32-11-0Page 6   Figure 3 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Nov 15/77 

5.  Main Gear Torsion Links
A.  The main gear torsion links prevent rotation between shock strut inner and outer cylinders without affecting the reciprocating action during normal operation of strut. The upper torsion link and bottom attachment of the lower drag strut share the same lugs on the shock strut outer cylinder. The lower torsion link is connected to lugs on the inner cylinder. (See figure 2.) Upper and lower torsion links are joined at their forward ends by a single bolt.
　
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：737 AMM 飞机维护手册 起落架 LANDING GEAR(21)