Question: What does sparking limit?
Answer: maximum speed

Question: What motor components most need replacement and maintenance? 
Answer: Brushes

Question: What are large brushes favorable for?
Answer: motor output

Question: Whate are small brushes favorable for?
Answer: speed

Question: What type of brushes are cheapest?
Answer: small

Question: How can the speed of larger brushes be increased?
Answer: Stiffer brush springs

Question: Besides wear, what is a downside of stiff brush springs?
Answer: lower efficiency

Question: What can a PM motor not be adjusted for?
Answer: speed control

Question: What is another name for PM fields?
Answer: stators

Question: What design feature does a PM motor lack?
Answer: field winding

Question: What do field windings provide?
Answer: flux

Question: Why do miniature PM motors use high energy magnets?
Answer: To minimize overall weight and size

Question: What are high energy magnets typically made of?
Answer: neodymium-iron-boron alloy

Question: What does the outer housing of a miniature motor resemble?
Answer: steel tube

Question: How do PMs rate against other types of electric motors?
Answer: least competitive

Question: What is the typical maximum range of universal motors?
Answer: 1000 watts

Question: What type of motor was used in trailway traction applications?
Answer: universal

Question: What is the result of using AC power on a DC motor?
Answer: efficiency losses

Question: What were universal motor pole pieces constructed from?
Answer: solid (un-laminated) iron

Question: What kind of motor can employ both AC and DC?
Answer: universal

Question: What component of a universal motor is most likely to fail?
Answer: commutator

Question: When is torque most important in universal motor applications?
Answer: starting

Question: Switching the field winding in washing machines causes the drum to agitate how?
Answer: forwards and in reverse

Question: How is stepped speed control achieved?
Answer: Multiple taps on the field coil provide

Question: At around what RMP do weed trimmer motors operate?
Answer: 10,000

Question: At around what RMP do miniature grinders operate?
Answer: 30,000

Question: What type of motor can universal motors operate much faster than?
Answer: SCIMs

Question: What attributes make universal motors desireable for consumer applications like hair dryers?
Answer: high speed and light weight

Question: What determines the properties of speed and torque?
Answer: shape of the rotor bars

Question: At high speed, where is the most current?
Answer: interior of the winding

Question: Is the current frequency higher or lower at high speed?
Answer: lower

Question: Changing the shapes of the bars creates what?
Answer: variable resistance

Question: Where can variable resistance be created?
Answer: rotor circuit

Question: Where might a resistor be attached?
Answer: rotor circuit

Question: What can a resistor control?
Answer: motor speed

Question: How might wasted power be salvaged?
Answer: inverter or separate motor-generator

Question: From where may a converter be fed?
Answer: rotor circuit

Question: What will a motor do if the load is reduced?
Answer: speed up

Question: What will a motor do if the load is increased?
Answer: slow down

Question: Where are slip losses dissipated?
Answer: secondary resistors

Question: How efficient is such a design?
Answer: very poor

Question: How are torque motors used in computer gaming?
Answer: feedback steering wheels

Question: A torque motor at low voltage provides what?
Answer: constant light tension

Question: A torque motor at high voltage provides what?
Answer: higher torque

Question: In a tape drive, what is not needed if a torque motor is used?
Answer: gears or clutches

Question: What element of a combustion engine does a governor monitor?
Answer: electrical pulses

Question: What is a governor connected to?
Answer: return spring

Question: What kinds of adjustments would a governor make?
Answer: small

Question: What would a governor do to a too-fast running engine?
Answer: reduce the current being applied to the motor

Question: How much slip does a synchronous motor have?
Answer: zero

Question: How does an induction motor produce torque?
Answer: slip

Question: Whithout rotor windings, how must a Hammond clock be started?
Answer: manually

Question: How can a synchronous motor be made more like an induction motor?
Answer: DC field

Question: How is current brought to the rotor in a synchronous motor?
Answer: Slip rings and brushes

Question: What do hysteresis synchronous motors' rotors do when slip rate decreases?
Answer: becomes temporarily magnetized

Question: When in operation, what do hysteresis synchronous motors poles do?
Answer: stay in place

Question: What do hysteresis synchronous motors resemble at startup?
Answer: induction motors

Question: How can a hysteresis synchronous motor's rotor be described?
Answer: a smooth cylinder

Question: What do the distributed poles of a hysteresis synchronous motor resemble?
Answer: PMSM

Question: What type of motor has two independent multiphase winding sets?
Answer: Doubly fed electric motors

Question: What advanage do independent multiphase winding sets have?
Answer: contribute active (i.e., working) power to the energy conversion process

Question: What is one of the independent multiphase winding sets configured for?
Answer: variable speed operation

Question: Doubly fed motors have what advantage over single fed?
Answer: twice the constant torque speed range

Question: A coreless DC motor is distinguished by what?
Answer: rapid acceleration

Question: What is absent in a coreless DC motor?
Answer: iron core

Question: What forms can the rotor take?
Answer: winding-filled cylinder, or a self-supporting structure

Question: What is a likely problem of coreless DC motors?
Answer: Overheating

Question: How does a coreless rotor compare to traditional rotors in terms of weight?
Answer: lighter

Question: What advantage does a coreless rotor have over traditional variants?
Answer: accelerate much more rapidly

Question: The lack of a metal mass in the core causes what function to be absent?
Answer: heat sink

Question: How is a coreless motor cooled?
Answer: forced air

Question: What was the original purpose for pancake motors?
Answer: drive the capstan(s) of magnetic tape drives

Question: What are advantages of pancake motors?
Answer: minimal time to reach operating speed and minimal stopping distance

Question: For what type of military applications are pancake motors currently used?
Answer: high temperature

Question: What type of servo-controlled systems use pancake motors?
Answer: high-performance

Question: What may servo motors be used for?
Answer: machine tools, pen plotters, and other process systems

Question: What must be well understood when applying a servo motor for use?
Answer: speed, torque, and power

Question: What factors limit performance of servo motors?
Answer: winding inductance and rotor inertia

Question: Large, slow servos can use what types of motors?
Answer: conventional AC or DC motors

Question: When might coreless motors be used in servo applications?
Answer: As dynamic response requirements increase

Question: How do servo motors differ from stepper motors?
Answer: position feedback is continuous

Question: How does a stepper system achieve stability?
Answer: a "home" switch

Question: What makes a printer home switch work?
Answer: position sensor

Question: What kind of counter keeps track of a print head's position?
Answer: bidirectional

Question: A stepper system's motor is relied on to not do what?
Answer: miss steps

Question: When are stepper motors most useful?
Answer: when precise rotations are required

Question: What two devices can describe a stepper motor?
Answer: DC electric motor and a rotary solenoid

Question: What do stepper motor rotors allign themselves with?
Answer: magnetic field produced by the energized field winding