Mechanical Engineering Terms with Meanings – A to Z

Mechanical engineering is a branch of engineering that uses the principles of the science of Mechanics and Materials to analyze, design, manufacture, and repair mechanical systems. It involves the production and use of heat and energy machinery in the construction, production, and operation of machinery and equipment.

We have prepared a list of common vocabulary words associated with Mechanical Engineers in an alphabetical order.

Mechanical Engineering Terms – A to Z List

Following are some basic words related to Mechanical Engineering along with their meanings:

Word Meaning
alternator Electromechanical device that converts mechanical energy to electrical energy in the form of alternating current.
ambient temperature Temperature of the air in the immediate vicinity of the apparatus or component.
amortisseur winding Embedded windings in the field poles of synchronous machines to aid starting and / or dampen rotor oscillations.
ampere SI base unit of electric current.
apparent power Measured in volt-amperes (VA) in an AC circuit.
armature The part of a machine which receives or delivers active power to the external electrical system.
asynchronous machine An AC machine in which the speed on load and the frequency of the system to which it is connected are not in a constant ratio.
American wire gauge Standardized wire gauge system used predominantly in the USA.
brush A sliding electrical contact, usually rotating.
capacitance The amount of electrical energy stored for a given electric potential.
chord The factor by which short pitching a coil reduces the back
cogging torque Magnetic interaction between stator and rotor resulting in undesired machine operation such as jerkiness.
coil Set of series connected turns.
coil pitch or span The number of tooth pitches which separate the slots in which the two sides of a coil are placed.
commutation Change-over switching in a periodic and automatic manner without interruption of the electric current.
commutator An assembly of insulated conducting segments connected to the rotating armature winding.
concentric winding A distributed winding in which the individual coils of each phase group per pole are concentric and have different coil spans.
conductor A material which contains movable electrical charges.
core loss The electrical losses in a machine caused by the magnetization of the core iron.
critical speed The rotating speed at which resonance occurs.
delta current machine The 3 phases are connected in series to form a closed circuit.
direct current machine A machine incorporating an armature winding connected via a commutator to a direct current system.
distribution factor Ratio of the actual voltage of a phase band to the arithmetic sum of the individual coil voltages.
duplex winding An armature winding in which the coil ends are connected to alternate commutator segments.
duty cycle Specified sequence of operating conditions.
eddy currents Localized magnetically induced currents in an iron core.
efficiency Ratio of output power to input power of a device.
electromotive force The force induced in a conductor when it is moved across a magnetic field. (e.m.f.)
exciter A source of the power to the field winding of an electrical machine.
foot pound The energy transferred on applying a force of 1 pound-force (lbf) through a displacement of 1 foot.
form wound coil Coil of square or rectangular insulated magnet wire preformed to fit into winding slots.
form factor Ratio of the root-mean-square value of an alternating quantity to its rectified value.
generator Rotating electric machine used to transform mechanical energy into electric energy.
harmonic content Difference between alternating quantity and its fundamental component.
hermetic machine Air-tight machine protected from the environment.
hertz SI derived unit for frequency defined as the number of cycles per second of a periodic function.
horsepower Unit of power. 1hp = 746W
impedance The ratio of the voltage to the electric current, a measure of opposition to time-varying electric current in an electric circuit.
inductance Property in an electric circuit where a change in the current induces an electromotive force that opposes the change in current.
induction motor An AC motor where power is supplied to the rotor by magnetic induction.
induction generator An induction machine, connected to a reactive power source, working as a generator.
insulation The materials and parts used to insulate conductive elements of a machine.
inverter Converter that changes direct electric current to single-phase or poly-phase alternating currents.
lap winding Armature winding with each coil of 2 conductors placed in slots 90° apart, connections made in adjacent segments of a commutator.
leakage current Electric current in an unwanted conductive path.
loop test Test to detect hot spots due to shorted electrical laminations.
magnetic flux density Strength of a magnetic field.
motor A machine which converts electrical energy into mechanical energy.
mush coil A wound coil where the conductors occupy random positions in the slot.
newton Force required to accelerate a mass of one kilogram at a rate of one meter per second per second.
PAM winding Pole Amplitude Modulation winding with connections giving speed combinations other than 2:1.
part winding start Starting with only part of the winding energized to reduce starting current.
phase voltage Voltage between the two terminals of a phase.
poles Magnetic poles created in a machine by windings.
power The rate at which work is performed.
random wound coil The conductors occupy random positions in the slot.
rates temperature rise The permitted rise in operating temperature above ambient when running on load.
reactance The resistance to AC current due to capacitance or inductance.
reactive motor Measured in var in an AC circuit.
regeneration Operation of a motor in a generator mode to feed energy back into the power supply.
regulation Amount of speed or voltage change due to load variations.
reluctance The ‘resistance’ of a magnetic circuit.
resistance Defined as the ratio of voltage to current.
rotor The rotating part of an electrical machine.
salient pole A field pole which projects from the yoke or hub towards the air-gap.
series excitation DC machine with field coils connected in series with the armature.
service factor The factor by which the rated power can be increased under specified conditions of service.
shaft currents Induced circulating currents due to machine asymmetries or supply voltage effects.
skew Non parallel stator and rotor slot alignment.
slip The difference between the synchronous speed and the actual speed of a rotor expressed as per unit or as a percentage of the synchronous speed.
slot A recess in a core in which the conductors of a winding may be placed.
space factor The ratio of the area of bare insulated copper conductors to the available slot area.
star delta starting A delta wound motor connected in star during starting to reduce inrush current.
full load speed Machine speed at rated load.
stator The stationary portion of a machine.
tolerance Permitted deviation between the declared value of a quantity and the measured value.
torque The rotational force produced by a motor.
breakdown torque Maximum torque an AC motor will develop.
starting torque The torque produced by a motor at initial switch on.
unbalanced magnetic pull Unequal radial pull on a rotor due to magnetic eccentricities in the air gap.
variable speed drive System for altering the rotational speed of an AC motor by controlling the frequency of the electrical supply.
volt Derived SI unit for electromotive force
watt SI unit of power.
wave winding Armature winding with each coil of 2 conductors placed in slots 90° apart, connections made in segments approximately 180° apart on the commutator.
winding factor The product of the Pitch Factor and the Distribution Factor. (kp x kd)
yoke Part of a device, composed of magnetic material and intended to complete a magnetic circuit.

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