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Related to motors: Induction motors, Electric motors


a. the engine, esp an internal-combustion engine, of a vehicle
b. (as modifier): a motor scooter
2. a machine that converts electrical energy into mechanical energy by means of the forces exerted on a current-carrying coil placed in a magnetic field
3. any device that converts another form of energy into mechanical energy to produce motion
a. Chiefly Brit a car or other motor vehicle
b. as modifier: motor spares
5. producing or causing motion
6. Physiol
a. of or relating to nerves or neurons that carry impulses that cause muscles to contract
b. of or relating to movement or to muscles that induce movement


A machine that converts electric energy into mechanical energy by utilizing forces produced by magnetic fields on current-carrying conductors. Also known as electric motor.
Pertaining to efferent nerves which innervate muscles and glands.
That which causes action or movement.


A machine that converts electrical into mechanical energy. Motors that develop rotational mechanical motion are most common, but linear motors are also used. A rotary motor delivers mechanical power by means of a rotating shaft extending from one or both ends of its enclosure (see illustration). The shaft is attached internally to the rotor. Shaft bearings permit the rotor to turn freely. The rotor is mounted coaxially with the stationary part, or stator, of the motor. The small space between the rotor and stator is called the air gap, even though fluids other than air may fill this gap in certain applications.

In a motor, practically all of the electromechanical energy conversion takes place in the air gap. Commercial motors employ magnetic fields as the energy link between the electrical input and the mechanical output. The air-gap magnetic field is set up by current-carrying windings located in the rotor or the stator, or by a combination of windings and permanent magnets. The magnetic field exerts forces between the rotor and stator to produce the mechanical shaft torque; at the same time, in accord with Faraday's law, the magnetic field induces voltages in the windings. The voltage induced in the winding connected to the electrical energy source is often called a countervoltage because it is in opposition to the source voltage. By its magnitude and, in the case of alternating-current (ac) motors, its phase angle, the countervoltage controls the flow of current into the motor's electrical terminals and hence the electrical power input. The physical phenomena underlying motor operation are such that the power input is adjusted automatically to meet the requirements of the mechanical load on the shaft. See Electromagnetic induction, Magnet, Windings in electric machinery

Both the rotor and stator have a cylindrical core of ferromagnetic material, usually steel. The parts of the core that are subjected to alternating magnetic flux are built up of thin steel laminations that are electrically insulated from each other to impede the flow of eddy currents, which would otherwise greatly reduce motor efficiency. The windings consist of coils of insulated copper or aluminum wire or, in some cases, heavy, rigid insulated conductors. The coils may be placed around pole pieces, called salient poles, projecting into the air gap from one of the cores, or they may be embedded in radial slots cut into the core surface facing the air gap. In a slotted core, the core material remaining between the slots is in the form of teeth, which should not be confused with magnetic poles. See Eddy current

Direct-current (dc) motors usually have salient poles on the stator and slotted rotors. Polyphase ac synchronous motors usually have salient poles on the rotor and slotted stators. Rotors and stators are both slotted in induction motors. Permanent magnets may be inserted into salient pole pieces, or they may be cemented to the core surface to form the salient poles.

The windings and permanent magnets produce magnetic poles on the rotor and stator surfaces facing each other across the air gap. If a motor is to develop torque, the number of rotor poles must equal the number of stator poles, and this number must be even because the poles on either member must alternate in polarity (north, south, north, south) circularly around the air gap.


A machine which converts electric power into mechanical power by means of a rotating shaft.
References in classic literature ?
He hummed peacefully and, his adjustment completed, tried out his motor for a minute or two, then shut it off and descended to the ground with the intention of stretching his legs and taking a smoke before continuing his return flight to camp.
And so she drove her motor forward again and then with her firm, white teeth set in grim determination she drove the steering lever far down to port with the intention of forcing the nose of her craft straight into the teeth of the wind, and the wind seized the frail thing and toppled it over upon its back, and twisted and turned it and hurled it over and over; the propellor raced for an instant in an air pocket and then the tempest seized it again and twisted it from its shaft, leaving the girl helpless upon an unmanageable atom that rose and fell, and rolled and tumbled--the sport of the elements she had defied.
I have been run over by a motor car," his patient said, speaking slowly and with something singularly agreeable in his voice notwithstanding its slight accent of pain.
Are you going back to London in the motor car, then?
Taylor had found the ingredients for chemical fuel, and the distilling of them had, with the motor trouble, accounted for their delay in setting out after me.
Warren was hurrying as fast as another motor car could bring him.
If you say the same thing to a child who does not yet know the word "motor," but does know the other words you are using, you produce a feeling of anxiety and doubt you will have to point and say, "There, that's a motor.
The word "motor" can make you leap aside, just as the motor can, but it cannot break your bones.
The child is not seeing a motor, but only remembering one; the hearer does not look round in expectation of seeing a motor coming, but "understands" that a motor came at some earlier time.
It required no more exertion on Saxon's part to start him than had been required on his part to start the motor.
Fascinated by the five-inch stream, sluiced out of the earth and back to the earth by the droning motor, he forgot his discourse and stood and gazed, rapt and unheeding, while his visitors drove on.
com/research/2534gv/world_electric) has announced the addition of the "World Electric Motors - Market Opportunities and Forecasts, 2014 - 2020" report to their offering.