27-21-00
 ALL  ú ú 01 Page 3 ú Jun 15/84
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

757
MAINTENANCE MANUAL

 D. Rudder Control Cables (Fig. 3)
_____________________
 (1)  
Two control cables are attached at the left and right forward quadrants under the flight deck floor. The cables run under the main cabin compartment and through the aft pressure bulkhead, up to the aft quadrant.

 (2)  
Three turnbuckles per cable are used for adjusting cable tension with rig pin R2 and R3 installed. Access to the forward set of turnbuckles is through the forward cargo compartment ceiling. The center set is accessed through the cabin floor and the aft set through access door 311AL.

 E.
Aft Quadrant, Feel, Centering and Trim Mechanism (Fig. 4)

________________________________________________
 (1)  
The aft quadrant, feel, centering and trim mechanism is located at the base of the vertical fin, above the autopilot servos. All mechanism inputs and outputs are connected to its offset torque tube. The aft quadrant transfers cable inputs from the rudder pedals to the torque tube. The quadrant also back-drives the cable system in response to rudder movement caused by autopilot and trim inputs. Other input sources are the trim actuator and three directional autopilot servos. The torque tube output consists of two control rods/pogos which provide ratio changer mechanism input. Two aft quadrant stops limit rotation of the aft quadrant. Rig pin hole R-3 provides a rigging position to fix the aft quadrant to the structural support.

 (2)  
Feel and centering functions are provided by a cam-roller-spring mechanism. It provides an increasing feel force to rudder pedal input and a centering force to return pedals and rudder to neutral when pedal deflection is removed. The mechanism consists of two arms, spring-joined at the wide end, and connected to the trim actuator at the other. The lower arm contains a roller which follows a detented cam face. The cam face is attached to the torque tube and pivots around the torque tube axis of rotation. Pedal force to move the roller out of the cam face detent is 14 pounds, (62 Newtons)increasing with pedal deflection to 72 pounds (320 Newtons) at full travel.

 F.
Rudder Trim Actuator

____________________
 (1)  The housing of the rudder trim actuator is attached to the vertical fin rear spar and the rod end is connected to the feel, centering and trim mechanism. Trim commands from the trim switch cause the actuator to extend or retract, which rotates the feel, centering and trim mechanism. This provides a new zero force pedal position corresponding to the trimmed rudder position. The actuator provides the ground point for the feel, centering and trim mechanism.
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 27-21-00
 ALL  ú ú 01 Page 4 ú Jan 28/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A

757
MAINTENANCE MANUAL

RA TURNBUCKLE STA 590
SEE A RB TURNBUCKLE
STA 610  RA TURNBUCKLE STA 1030
RB TURNBUCKLE STA 1050
SEE B
UP
FLOOR LINE RA TURNBUCKLE WL 260
RB TURNBUCKLE WL 240
RUDDER CABLE
CABLE LOCATION
(FUSELAGE CROSS SECTION)
 (VIEW LOOKING FORWARD)

RA
RIG PIN
HOLE R-3RIG PIN
HOLE R-2
RB
RA RB
AFT QUADRANT
A
B
TURNBUCKLE INSTL (TYPICAL)
Rudder Control Cables
Figure 3

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 27-21-00
 ALL  ú ú 01 Page 5 ú Dec 15/83
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
757
MAINTENANCE MANUAL

OUTPUT ROD TO RATIO CHANGER (2)TRIM ACTUATOR
PANEL
324AL

TORQUE TUBE
CABLE RA
RIG PIN
SEE A AND SEE B HOLE R-3

CABLE RB
CENTER OF ROTATION FEEL AND CENTERING
SPRINGSOUTPUT
TO RATIO
CHANGER

FWD  INPUT RODS FROM AUTOPILOT SERVOS
CABLE TORQUE QUADRANT TUBE
A A
TRIM
ACTUATOR ANTI-ROTATION CLEVISA/P
SERVO RIG PIN CONTROL HOLE R-3 ROLLER ROD (3)
CAM A ELECTRICAL CONNECTOR
　
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