3. Autothrottle Servomechanism
A. The autothrottle servomechanism is composed of two parts, a torque switch mechanism and an actuator assembly.
B. The torque switch mechanism consists of input and output quadrants with an integral cam to operate switches, a mechanism to permit pilot override of the servo drive, a means of generating braking friction to prevent throttle creep in the manual mode and a support framing with two removable control cable guards and locating dowel pins.
C. The actuator assembly consists of a servo motor with reduction gearing to form the prime mover, an electromagnetic clutch, a tachometer to provide servo motor speed signal, and electronic circuitry which when controlled by appropriate computer software would permit driving the output when the input has contacted a stop at the idle position.
4. Autothrottle Longitudinal Accelerometer
A. The autothrottle accelerometer is located in the electronic equipment bay outboard of the airplane battery. The accelerometer is supplied with 26 volts ac excitation from the autothrottle computer and produces an ac output signal whose voltage amplitude and phase are related to the acceleration sensed by the component in the horizontal (fore and aft) plane of the airplane. The output signal is routed to the autothrottle computer.
5. Engine Thrust Lever Position Transmitters
A. A thrust lever position transmitter consisting of a linear velocity displacement transducer (LVDT) is located on the left side of each engine between the main frame and the engine cross-shaft crank. The component is provided with 26 volts ac excitation from the autothrottle computer. Its ac output signal, directly related to thrust lever position, is applied to the autothrottle computer.
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22-31-01 Page 10 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Oct 20/85
4. Autothrottle Servomechanism (BA G-BKYA and on; WA N236WA thru N241WA)
A. The autothrottle servomechanism is composed of two parts, a torque switch mechanism and an actuator assembly.
B. The torque switch mechanism consists of input and output quadrants with an integral cam to operate switches, a mechanism to permit pilot override of the servo drive, a means of generating braking friction to prevent throttle creep in the manual mode and a support framing with two removable control cable guards and locating dowel pins.
C. The actuator assembly consists of a servo motor with reduction gearing to form the prime mover, an electromagnetic clutch, a tachometer to provide servo motor speed signal, and electronic circuitry which when controlled by appropriate computer software would permit driving the output when the input has contacted a stop at the idle position.
5. Autothrottle Longitudinal Accelerometer
A. The autothrottle accelerometer is located in the electronic equipment bay outboard of the airplane battery. The accelerometer is supplied with 26 volts ac excitation from the autothrottle computer and produces an ac output signal whose voltage amplitude and phase are related to the acceleration sensed by the component in the horizontal (fore and aft) plane of the airplane. The output signal is routed to the autothrottle computer.
6. Engine Thrust Lever Position Transmitters
A. A thrust lever position transmitter consisting of a linear velocity displacement transducer (LVDT) is located on the left side of each engine between the main frame and the engine cross-shaft crank. The component is provided with 26 volts ac excitation from the autothrottle computer. Its ac output signal, directly related to thrust lever position, is applied to the autothrottle computer.
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Oct 20/85 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 22-31-01 Page 10A/10B
6. Automatic Flight Control System (AFCS) Mode Control Panel (MCP)
A. The AFCS MCP controls both autothrottle and A/P- F/D operation. Six controls on the panel are provided for use with the autothrottle system. These consist of the following: A/T ARM-OFF, IAS/MACH speed adjust, EPR MODE SELECT, SPEED mode select, LVL CHG mode select, and V NAV/PDC. The EPR, SPEED, LVL CHG and V NAV/PDC controls are combined pushbutton switch/lamps which illuminate when operated.
(1)
The autothrottle engage (ARM-OFF) switch is a solenoid-held, two-position toggle switch. When operated, the switch remains in the ARM position only if all A/T engage interlocks are satisfied. If power or engage logic is interrupted or an A/T disconnect switch is operated, the switch reverts to the OFF position.
(2)
The rotary IAS/MACH speed control provides adjustment of the speed reference marker (bug) on the captain's and first officer's IAS/MACH indicators. The bug, which travels along the periphery of the indicator, can be set to any desired speed within the range 110 to 440 knots. A digital readout of the selected speed is displayed in a window above the control. This control is directly associated with the autothrottle system when the autothrottle system is engaged in SPEED mode.
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