22-32-00
ALL ú ú 02 Page 4 ú Sep 20/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757 MAINTENANCE MANUAL
THRUST LEVER
SEE A AUTOTHROTTLE
DISENGAGE
SWITCH
(2 LOCATIONS)
CONTROL GO-AROUND
STAND SWITCHES
AUTO THROTTLE
ASSEMBLY FLIGHT
COMPONENTS DECK
FLOOR
SEE B FWD
THRUST LEVER COMPONENTS
A
CONTROL ROD
CLUTCH PACK
ASSEMBLY
(2 LOCATIONS)
GEARBOX ASSEMBLY
AUTOTHROTTLE SERVOMOTOR GENERATOR
ELECTRICAL CONNECTOR
AFT
MICROSWITCH
PACK ASSEMBLY
ELECTRICAL CONNECTORS
AUTOTHROTTLE ASSEMBLY COMPONENTS
ELECTRICAL
B
1
CONNECTORS
1 GUN 001-008, 010, 101-104 WITH SB 78-32 AND GUN 009, 011-099, 105-999
Thrust Management System Components
Figure 2
C98968
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22-32-00
ALL ú ú 11 Page 5 ú Jun 20/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL
(1) Autothrottle Servomotor Generator
(a) The autothrottle servomotor generator is located below the flight deck floor under the thrust lever control stand. This device automatically controls thrust lever position.
The A/T servomotor generator has two main components. A two-phase motor that moves the throttles as commanded by the TMC and a single phase generator (or tachometer) which provides servo rate feedback to the TMC.
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The servomotor has a fixed field winding which uses 115 vac excitation and two control windings which use 36 vac excitation (controlled by the servo power amplifier in the TMC). The servomotor drives at a rate proportional to the pulse width of the control voltage. Both excitation voltages are applied when the autothrottle is engaged.
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The tachometer is an AC generator with a linear relationship between shaft rpm and AC output voltage. The tachometer uses 115 vac excitation on the input winding and provides tachometer output for servo loop damping on the output winding.
(b) The splined output shaft of the servomotor generator mates with the gearbox assembly. Three bolts hold the servomotor generator to the gearbox. With the servomotor generator and gearbox reduction, the maximum thrust lever rate is 14 degrees/sec.
(2)
A/T Disengage Switch
(a) An autothrottle disengage switch (double-push reset) is on the end of each thrust lever. It is a normally closed switch which, when depressed, disengages the autothrottle and provides an autothrottle disengage warning. A second press of the switch resets the warning circuits.
(3)
Go-Around Switch
(a) One palm-operated go-around switch is at the base of each thrust lever. The go-around switches are wired in series with the go-around logic in the TMC. Actuating the switch engages the go-around mode if the go-around mode is armed (Ref 22-11-00, Autopilot/Flight Director Power for additional description).
(4)
Clutch Pack Assembly
(a) The clutch pack assembly is directly under the thrust lever control stand. The clutch pack consists of two clutch assemblies mounted on a common shaft. One clutch is used by each thrust lever. Manual pressure applied to the thrust levers operates the cam mechanism that releases the clutch. The cam mechanism consists of normally closed brake shoes that transmit the autothrottle drive to the thrust lever linkage and autothrottle cable quadrant. Manually moving the thrust levers cams the brake shoes open and drives only the cable quadrant. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 AMM 飞机维护手册 自动飞行 AUTOFLIGHT 2(113)
