Torque synchro transmitters and receivers are used often in ordnance equipment to transmit information electrically from one point to another. The synchro transmitter sends out the signal and the synchro receiver receives it.

These synchros are connected in such a way that any amount of rotation of the transmitter rotor causes the rotor of the receiver to turn the same amount. The receiver either indicates the value of the signal by turning a dial, as shown in figure 5-25, or positions a light mechanical load, such as the valves shown in figure 5-26.

If it is desired that a director control a gun or GMLS by use of a torque synchro system, the transmitter rotor will be geared to the director so that when the director is moved, the rotor of the transmitter is also moved. An electrical signal representing the amount of rotation of the transmitter rotor is transmitted over wires to a synchro receiver located at the mount or launcher. This signal causes the rotor of the synchro receiver to turn, or attempt to turn, the same amount that the transmitter rotor has turned. If the synchro receiver is connected to a power drive through a servo system, as shown in figure 5-27, it will control the drive and thereby cause the gun to turn the same amount as the director.

In synchro transmission, any movement of the rotor in the torque synchro transmitter produces a corresponding movement of the rotor in the torque

Figure 5-26.-Torque synchros used to move valves.

Figure 5-27.-Basic synchro system.

synchro receiver. The position of the rotor of a synchro receiver always conforms to the position of the rotor in a synchro transmitter.

If reversing the direction of rotation of a receiver becomes necessary, interchange stator leads S1 and S3; S2 represents electrical zero. Changing the S2 lead would introduce an error of 120 degrees.