This cylinder consists of four separate banks of servomechanisms constructed as a unit. Figure 10-7 shows the fore-and-aft bank of the servo cylinder. The other banks are similar in design and operation, except as noted in the following paragraphs. The hydraulic power pistons of each bank help flight control movements before the movement is sent to the mixing unit. The cylinder operates on mechanical input during manual operation of the flight controls. The cylinder operates on electrical input from the ASE, and on electrical input from the stick trim system.

Each of the four banks operates in a single area of control functioning, providing fore-and-aft, lateral, collective, and directional hydraulic aid. Each bank has a mechanical and electrical input hydraulic servo valve capable of displacing the pilot valve shuttle for ASE operation. Additionally, the fore-and-aft and the lateral banks have a pair of solenoid-operated stick trim valves. These valves control fore, aft, and lateral movements through the stick trim system.


Figure 10-7.Auxiliary servo cylinder.

The directional bank uses a pedal damping piston that restricts sudden heading changes. The auxiliary servo cylinder operates at 1,500-psi hydraulic pressure supplied by the auxiliary hydraulic system.

The mixing unit consists of a system of bell cranks and linkage. The unit coordinates and transfers independent movements of the lateral, forward, aft, and directional controls. Movement is sent to the primary servo cylinders and the rotary rudder. The mixing unit also integrates collective pitch control movements with those of the lateral, fore-and-aft, and directional systems. It causes the controls to move the three primary servo cylinders simultaneously in the same direction. It changes the pitch on the rotary rudder blades to compensate for the change in pitch of the rotary-wing blades.