DOWN AND LOCKED
Main Gear Operating Sequence
Figure 3 (Sheet 1)
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A 737-300/400/500MAINTENANCE MANUAL
UP AND LOCKED
Main Gear Operating Sequence
Figure 3 (Sheet 2)
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A 737-300/400/500MAINTENANCE MANUAL
4. Main Gear Lock Mechanism
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A. The main gear lock mechanism positively locks the gear in retracted or extended position. The lock consists of a hook, two hydraulic actuators, spring bungees, a lock strut, and operating linkage (Fig. 4). In the retracted position, the hook engages a roller mounted on the universal side strut fitting. In the down position, the lock strut assumes an overcenter position to prevent the side strut from folding. The uplock hook and the lock strut are connected to individual actuators. The actuators are mounted on the reaction link. Sensors for the position indicating and warning system proximity switches are located in two places. The downlock sensor is on the side strut, near the lower end of the lock strut. The uplock sensor is mounted between the uplock hook and the lower end of the uplock spring bungees.
B. Normal operation of both up and down locks is by hydraulic pressure directed to the lock actuators. Provision is made to release the uplock in the absence of hydraulic pressure by means of a manual extension system. Spring bungees provide a force to hold the locks in the locked or unlocked positions. When the gear is released by the manual extension system, the lock strut swings into locked position as the gear falls. On the final extension movement, the spring bungees pull the lock strut into overcenter position.
5. Main Gear Lock Actuator
_______________________
A. Main gear lock actuators operate the main gear lock mechanism to permit retraction or normal extension of the landing gear (Fig. 5). Actuators are hydraulic piston type. Two actuators are mounted on the reaction link of each main gear. One on the inboard end to operate the uplock and one on the outboard end to operate the downlock. The downlock actuator extends to push the lock strut across the overcenter position and to start the side strut folding. Retraction of the actuator pulls the lock strut into the overcenter locked position when the gear extends. The uplock actuator extends to swing the uplock hook away from the uplock roller and release the gear. Uplock actuator retraction pushes the hook outboard to fully engage the uplock roller.
6. Main Gear Lock Springs
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A. The main gear lock springs are arranged to apply a load to hold the locks in either engaged or disengaged positions. Lock springs consist of tension springs with one end attached to a fixed pivot point and the other end to the appropriate lock mechanism. When the locks operate, the spring ends attached to lock mechanism swing through an arc the highest point of which is in line with the spring fixed pivot point. Therefore, an overcenter effect keeps locks in position, fully open or closed.
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A
737-300/400/500MAINTENANCE MANUAL
UPLOCK SPRING
DOWNLOCK UPLOCK
ACTUATOR UPLOCK CRANK ACTUATOR
DOWNLOCK UPLOCK SPRING LINK
UPLOCK HOOK
STOP LINK
REACTION LINK
SHOCK
STRUT
L0CK STRUT
(DOWNLOCK)
SIDE STRUT
GEAR DOWN AND LOCKED
UPLOCK
DOWNLOCK UPLOCK UPLOCK CRANK STOP LINK
ACTUATOR ACTUATOR LINK
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本文链接地址：737-300 400 500 AMM 飞机维护手册 起落架 LANDING GEAR 2(66)
