SYNCHROS

LEARNING OBJECTIVES

Learning objectives are stated at the beginning of each chapter. These learning objectives serve as a preview of the information you are expected to learn in the chapter. The comprehensive check questions placed throughout the chapters are based on the objectives. By successfully completing the Nonresident

Training Course (NRTC), you indicate that you have met the objectives and have learned the information. The learning objectives for this chapter are listed below.

Upon completing this chapter, you will be able to:

• Define the term "synchro."
• State the primary purpose of a synchro.
• Explain the importance of synchros in naval equipment.
• Name the two general classifications of synchros.
• Explain the differences between torque and control synchros.
• Name the seven functional classes of synchros and list all inputs and outputs.
• Name the two types of synchro identification codes.
• Interpret all synchro markings and identify the particular codes used.
• Draw the five standard schematic symbols for synchros and identify all connections.
• Describe the general construction and physical appearance of synchro rotors and stators.
• Name the two common types of synchro rotors, giving an application of each.
• List the different synchro characteristics and give a brief explanation of each.
• State the advantage of using 400-Hz synchros over 60-Hz synchros.
• Explain the operation of a basic synchro transmitter and receiver.
• State the difference between a synchro transmitter and a synchro receiver.
• List the basic components that compose a torque synchro system.
• Explain the operation of a simple synchro transmission system.
• Define the term "correspondence" and explain how it is used in a simple synchro system.
• Explain the principle behind reversing the S1 and S3 leads on a synchro receiver and how this action affects receiver operation.
• Explain what happens when the rotor leads on a synchro transmitter or receiver are reversed.
• State the purposes of differential synchros.
• Name the two types of differential synchros and give a brief explanation of each.
• Explain the difference between the torque differential transmitter and the torque differential receiver.
• Name the components that make up the TDX and the TDR synchro systems.
• Explain how the two differential synchro systems add and subtract.
• State the wiring changes required to convert the differential synchro systems from subtraction to addition.
• State the purposes and functions of control synchros.
• Name the different types of control synchros.
• Explain how the CX and CDX differ from the TX and TDX.
• Explain the theory and operation of a control transformer.
• List the basic components that compose a control synchro system.
• Explain the operation of a control synchro system and how it is used to control a servo system.
• State the purpose and function of the synchro capacitor.
• Explain how synchro capacitors improve the accuracy of synchro systems.
• Explain the method used to connect synchro capacitors in a circuit.
• Define single and multispeed synchro systems.
• State the purposes and functions of multispeed synchro systems.
• Stale the purposes for zeroing synchros.
• Name three common synchro zeroing methods and give a brief explanation of each.
• Explain the different troubleshooting techniques used in isolating synchro malfunctions and breakdowns.

SYNCHRO FUNDAMENTALS

Synchros play a very important role in the operation of Navy equipment. Synchros are found in just about every weapon system, communication system, underwater detection system, and navigation system used in the Navy. The importance of synchros is sometimes taken lightly because of their low failure rate. However, the technician who understands the theory of operation and the alignment procedures for synchros is well ahead of the problem when a malfunction does occur. The term "synchro" is an abbreviation of the word "synchronous." It is the name given to a variety of rotary, electromechanical, position-sensing devices. Figure 1-1 shows a phantom view of typical synchro. A synchro resembles a small electrical motor in size and appearance and operates like a variable transformer. The synchro, like the transformer, uses the principle of electromagnetic induction.

Figure 1-1. - Phantom view of a synchro.

Synchros are used primarily for the rapid and accurate transmission of information between equipment and stations. Examples of such information are changes in course, speed, and range of targets or missiles; angular displacement (position) of the ship's rudder; and changes in the speed and depth of torpedoes. This information must be transmitted quickly and accurately. Synchros can provide this speed and accuracy. They are reliable, adaptable, and compact. Figure 1-2 shows a simple synchro system that can be used to transmit different as of data or information In this system, a single synchro transmitter furnishes information to two synchro receivers located in distant spaces. Operators put information into the system by turning the handwheel. As the handwheel turns, its attached gear rotates the transmitter shaft (which has a dial attached to indicate the value of the transmitted information). As the synchro transmitter shaft turns, it converts the mechanical input into an electrical signal, which is sent through interconnecting wiring to the two synchro receivers. The receiver shafts rotate in response to the electrical signal from the transmitter. When these shafts turn, the dials attached to the shafts indicate the transmitted information.

Figure 1-2. - Data transfer with synchros.

By studying the simple synchro system, you can see that information can be transmitted over long distances, from space to space, and from equipment to equipment.

In addition to supplying data by positioning dials and pointers, synchros are also used as control devices in servo systems. When the synchro and the servo are combined, they work as a team to move and position heavy loads.

The methods used to accomplish this are covered in detail in the next chapter.

Q.1 What is the name given to a variety of rotary electromechanical, position sensing devices?
Q.2 What is the primary purpose of a synchro system?