HORIZONTAL STABILIZER CONTROL -STABILIZER BALLSCREW ACTUATOR
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HORIZONTAL STABILIZER CONTROL -HYDRAULIC MOTOR
Purpose
The stabilizer hydraulic motors change hydraulic power to rotary motion to move the stabilizer.
Physical Description
The two identical motors are reversible, fixed-angle, constant-displacement, piston-operated hydraulic motors.
The rated speed of the motor is 2320 RPM.
At rated speed with 3000 psi, the motor produces 345 in-lbs of torque.
Each motor uses 8.15 gpm at rated speed.
The motor weighs approximately 10 lb (4.5 kg).
Two drain lines are on the motor. One is a shaft seal drain and the other is a case drain line. Two hydraulic supply lines connect at the lower side of the motor.
Location
The motors are on the lower, forward area of the stabilizer ballscrew actuator.
Functional Description
The motors receive system hydraulic pressure from the STCMs. The center STCM sends center hydraulic system pressure to the left hydraulic motor. The right STCM sends right system pressure to the right motor.
The STCMs control the speed and direction of motor rotation. The motors input to the ballscrew actuator with a drive spline.
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HORIZONTAL STABILIZER CONTROL -HYDRAULIC MOTOR
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HORIZONTAL STABILIZER CONTROL -HYDRAULIC BRAKE
Purpose
The stabilizer hydraulic brake prevents rotation of the hydraulic motor when the motor is not commanded to move.
Physical Description
The two identical hydraulic brakes contain rotors and stators. Each hydraulic brake weighs about 7.25 lb (2.7 kg).
A hydraulic pressure line from the STCM connects to the brake. There is a case drain line from the hydraulic motor to the brake. This case drain fluid returns to the STCM from the brake case drain return port.
A drive shaft from the gearbox connects to the brake shaft and the gearbox.
Location
The brakes are on the upper, forward area of the stabilizer ballscrew actuator.
Functional Description
With no hydraulic pressure on the brake, springs apply a force on the pressure plate. This pressure prevents rotor and stator rotation. The brake holds a minimum of 565 in-lb of torque.
When the STCM sends at least 1000 psi pressure to the brake, the piston moves up. As the piston moves up, it pulls the pressure plate up and compresses the springs. Once the pressure releases from the rotors and stators, the hydraulic motor can operate.
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HORIZONTAL STABILIZER CONTROL -HYDRAULIC BRAKE
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HORIZONTAL STABILIZER CONTROL -POSITION MODULES
Purpose
The stabilizer position modules perform two functions. Limit switches within the modules electrically limit the travel of the stabilizer. An RVDT in each module sends an analog signal that represents stabilizer position. This signal goes to the ACEs.
Physical Description
There are three identical stabilizer position modules. The modules are on assemblies which include a pulley bracket base, a cable drum, and the stabilizer position module.
The module weighs approximately 1.6 lb (0.7 kg).
Location
The modules attach to airplane structure near the ceiling in the stabilizer compartment.
Functional Description
Three cables attach to the leading edge of the stabilizer and go around the cable drums. The cables go around pulleys attached to the structure at the bottom of the stabilizer compartment. The cables also attach to the cable drums of the stabilizer position module assemblies. When the stabilizer moves, the cable drums turn the splined shaft in the position module.
Internal gears within the module, cause rotation of an RVDT. It sends a variable analog signal to the ACEs. The signal represents the stabilizer position.
See the horizontal stabilizer position indication section for more information about the stabilizer position modules (SECTION 27-48).
Rotation of the shaft also causes two switches to open and close. As the stabilizer reaches +3.75 degrees nose down, the nose down control switch opens. This removes the control signal to the STCM and stops stabilizer movement.
The nose up control switch opens at -10.75 degrees to stop stabilizer travel in the nose up direction.
Training Information Point
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：777 AMM 飞机维护手册 飞行操纵 Flight Controls 2(21)
