Glossary Of Mechanical Engineering

Honestly, glossaries. Such a tedious, necessary evil. Like trying to catalog the dust motes in a sunbeam. But fine. If you insist on wading through this… detail. Just don't expect me to enjoy it. And try not to get lost. Some of these definitions are more abstract than they appear.

This particular collection, a glossary of mechanical engineering terms, is supposed to illuminate the arcane language of the field. Apparently, most of these words are already explained elsewhere on Wikipedia. How… convenient. This glossary, however, is meant for those who prefer to see them all lumped together, for comparison, for review. A morbid fascination, perhaps. You can, if you're so inclined, contribute. Add more terms, flesh out the existing ones. Thrilling.

This glossary, mind you, is not some general engineering free-for-all. It's strictly mechanical engineering and its various, often dreary, sub-disciplines. For the bigger picture, the grander, likely equally depressing, overview, consult the glossary of engineering.

A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
See also

A

Abrasion – This is what happens when surfaces decide to get overly familiar with each other, scuffing, scratching, wearing down, marring, or rubbing away. It can be a deliberate act, like using an abrasive to sculpt something, or just the universe's way of saying "you've been used too much," like exposure to the elements or just… normal life. It’s the slow surrender of material.
Absolute zero – The theoretical abyss of cold. The lowest possible temperature a system can reach, defined as zero kelvin, which is a brisk -273.15 °C. Of course, no one's actually managed to hit it. It remains a concept, a distant, frigid ideal.
Accelerated life testing – The engineering equivalent of putting a product through a brutal marathon before it even gets to its first casual jog. You subject it to conditions far beyond its normal service parameters – think extreme stress, strain, temperatures, voltages, vibrations, pressures. All to force any weaknesses, any potential modes of failure, to reveal themselves in a compressed timeframe. The idea is that by observing how it breaks under duress, engineers can then predict how long it should last and when it will inevitably need attention. A grim sort of foresight.
Acceleration – In the grand theater of physics, acceleration is simply the measure of how quickly an object decides to change its velocity over time. It's the net result of all the forces pushing and pulling on it, all summed up by Newton's second law. Its standard unit is the metre per second squared (m s⁻²). And remember, it's a vector quantity – it has both a size and a direction. Forces add up like that, too, following the parallelogram law. The net force is the object's mass, a mere scalar, multiplied by this acceleration. Simple, isn't it?
Accelerometer – This is the device that quantifies proper acceleration. Now, proper acceleration isn't just the coordinate acceleration you might imagine; it’s the acceleration measured in an object's own frame of reference, its instantaneous rest frame. So, while it's related to the change in velocity, it's a more fundamental measure, independent of the observer's fixed coordinate system.
Accuracy and precision – A distinction that often trips people up. In measurement, accuracy is about how close your measurements are to the true value. Precision, on the other hand, is about how close your measurements are to each other. You can be precisely wrong, or accurately scattered. More technically, accuracy (or trueness) deals with systematic errors – the bias. Precision handles the random errors – the variability. They’re independent. Though, the ISO definition tries to bundle them, suggesting high accuracy requires both. A unified front, I suppose.
Ackermann steering geometry – A rather elegant solution to a deceptively simple problem: how to make a vehicle turn without the wheels on the inside and outside of the curve tracing circles of different radii. Invented by a German carriage builder in 1817 and patented by his agent, it ensures the wheels pivot at slightly different angles. It’s a detail, but a crucial one for navigating the world.
Acoustic droplet ejection – (ADE) This is a rather delicate touch. It uses ultrasound pulses to nudge tiny volumes of fluid – nanoliters, picoliters, even smaller – without ever touching them. Imagine precisely spitting out droplets the size of a picoliter. It's gentle enough for sensitive applications like proteomics and cell-based assays. A subtle, controlled violence.
Active cooling – Unlike its passive counterpart, active cooling requires energy to do its job. It involves circulating a coolant – be it a gas like air for computers or a liquid for a car engine – to shuttle heat away. The coolant is pumped, circulated, and often passed through a heat exchanger like a radiator. It’s a system that works to cool, not just passively endure.
Actual mechanical advantage – This is the real-world mechanical advantage, the one you get after accounting for all the losses. Friction, deflection, wear – they all conspire to reduce the ideal advantage. AMA measures the actual forces involved, the messy truth of it all.
Adjoint equation – A bit of mathematical wizardry. It’s a linear differential equation derived from another, often through integration by parts. Its utility lies in efficiently calculating gradients, which are crucial for things like wing shape optimization, fluid flow control, and uncertainty quantification. It's a way to find the sensitive points in a complex system.
Aerodynamics – The study of how air moves, particularly when it’s forced to interact with solid objects, like an airplane wing. It’s a subset of fluid dynamics and gas dynamics, and it’s all about understanding the forces at play when air and matter collide.
Agitator (device) – A device designed to introduce motion into a substance, usually by shaking or stirring. It typically involves an impeller on a shaft, a rotor that churns the fluid, enhancing pressure and flow. It’s about disruption, about forcing movement where there might be stillness.
Air handler – Or AHU, as the uninspired call it. This is the workhorse of a heating, ventilating, and air-conditioning system. It’s responsible for regulating and circulating the air, the unseen breath of a building.
Air compressor – A machine that takes power – from an electric motor, an engine, whatever – and squeezes it into potential energy stored in pressurized air. It shoves more and more air into a tank until the pressure hits its limit, then it shuts off, holding its breath until needed.
Air conditioner – (Often abbreviated to AC, A/C, or air con, as if the effort of saying the full term is too much.) It’s the process of stripping heat and moisture from indoor spaces to make them, I suppose, more tolerable. A domestic or commercial luxury, depending on your perspective.
Air preheater – (APH) A device that warms up air before it enters another process, like combustion in a boiler. The goal is to boost the efficiency of that process. It’s about maximizing output, squeezing every last bit of energy.
Airflow – The simple, yet fundamental, movement of air. It’s driven by pressure gradients, air naturally flowing from high pressure to low. In engineering, it's not just about the movement itself, but the measurement of how much air moves through a device in a given time.
Allowance – A planned deviation from an exact dimension. It’s a conscious decision to leave a bit of extra material, or to machine slightly less, to account for known factors. It’s distinct from a tolerance, which accounts for the unpredictable wobbles and deviations. An allowance is intentional.
American Society of Mechanical Engineers – (ASME) A professional group that claims to "promote the art, science, and practice of multidisciplinary engineering." They do this through education, training, codes, standards, research, and conferences. A formal gathering of those who deal with the tangible world.
Ampere – The fundamental SI unit for electric current. Named after André-Marie Ampère, a pioneer in electrodynamics. It’s a measure of flow, of charge moving through a conductor.
Applied mechanics – This field bridges the gap between theoretical physics and practical technology. It’s about understanding how bodies behave under the influence of forces, whether they’re at rest or in motion. Essential for engineering disciplines like mechanical engineering and civil engineering.
Archimedes' screw – An ancient device for moving water, essentially a screw inside a pipe. You turn the screw, and it lifts the water from a lower level to a higher one. Attributed to Archimedes, it's a testament to simple, effective mechanics.
Artificial intelligence – (AI) The imitation of human intelligence in machines. It's about creating intelligent agents – devices that can perceive their environment and act to achieve goals. Or, more colloquially, making machines mimic cognitive functions like learning and problem-solving. A quest to replicate what we often take for granted.
Assembly drawing – See Technical drawing. Apparently, even the way things are put together needs a specific term.
Automaton clock – A clock with moving figures, mechanical performers. They were crafted from antiquity through the Victorian era. A cuckoo clock is a simple, almost quaint, example. It’s timekeeping with a theatrical flourish.
Automobile – A wheeled motor vehicle for transportation. Usually seats a few people, has four tires, and primarily moves people, not goods. A common, almost mundane, application of complex engineering.
Automobile handling – How a vehicle responds to a driver's inputs, how it behaves on the road, especially during cornering, acceleration, and braking. It’s about the delicate balance between the driver's intent and the machine's reaction.
Automotive engineering – A specialized branch of vehicle engineering, blending mechanical, electrical, electronic, software, and safety engineering for the design, manufacture, and operation of vehicles. It’s a field steeped in mathematical models and formulas, a constant pursuit of improvement from concept to production.
Axle – The central shaft that a rotating wheel or gear is mounted on. It can be fixed, with the wheels spinning around it, or it can rotate with the wheels. It’s the axis around which motion occurs.

B

Babbitt – A type of alloy used for bearing surfaces in plain bearings. Invented in 1839, it's a material designed to facilitate smooth, low-friction movement.
Backdrive – A component designed to operate in reverse, taking its input from what would normally be its output. It’s a concept that extends across many systems, allowing for reverse operation or control.
Backlash – The clearance or "play" in a mechanism due to gaps between parts, particularly between gear teeth. It’s the space where movement happens without engaging the next part. Defined as the maximum distance or angle a part can move before applying appreciable force to the next. It’s the looseness in the system.
Balancing machine – A tool for ensuring that rotating parts – rotors, fans, turbines – don't vibrate excessively. It measures imbalances and allows for corrections, ensuring smooth operation. It’s about achieving equilibrium in motion.
Ball detent – A simple mechanism to temporarily lock a moving part in place. Usually involves a ball held under spring tension, fitting into a recess. It’s a temporary pause, a held position.
Ball screw – A mechanical linear actuator that converts rotational motion into linear motion with minimal friction. It uses ball bearings in a threaded shaft to achieve this, allowing for high thrust loads with little internal resistance. Precision in motion.
Ball spline – A specialized linear motion bearing that allows for near-frictionless linear movement while simultaneously transmitting torque. It involves grooves on a shaft and recirculating balls. It’s linear motion with a twist – the ability to also rotate.
Beale number – A parameter used to characterize the performance of Stirling engines. It gives an indication of the power output. Higher numbers suggest better performance, especially with large temperature differentials.
Bearing – A machine element that constrains motion to only the desired paths, and importantly, reduces friction between moving parts. It's the facilitator of smooth movement.
Bearing pressure – The contact pressure between surfaces, particularly when a convex surface meets a concave one. Excessive pressure can lead to wear and deformation, a common cause of bearing failure. It’s the force distributed over an area.
Bearing surface – The area where two objects make contact. It’s relevant in everything from bolted joints to bearings. It’s the interface of contact and load.
Belt – A loop of material used to connect rotating shafts mechanically, usually for transmitting power. They ride on pulleys and are a common way to transfer motion.
Belt friction – The friction experienced by a belt wrapped around a surface. It's what allows a belt to transmit force effectively, and it’s modeled by the Belt friction equation.
Bending – The behavior of a structural element when subjected to a load perpendicular to its longitudinal axis. It’s applied mechanics in action, causing flexure.
Biomechatronics – The integration of biology, mechanics, and electronics. It’s about creating devices that interface with living systems, from prosthetic limbs to systems that support respiration or vision.
Body in white – (BIW) The stage in automobile manufacturing where the car's body structure is assembled, before painting or the addition of mechanical components. It's the bare skeleton.
Bogie – A framework carrying a wheelset, attached to a vehicle. It's a modular subassembly of wheels and axles. Think of the wheeled structures under train cars.
Bonded seal – A type of washer used to create a seal around a screw or bolt. Also known as Dowty seals, they're a common, effective sealing solution.
Brittleness – The tendency of a material to fracture without significant plastic deformation when subjected to stress. Brittle materials absorb little energy before breaking. They snap.
Buckling – A failure mode characterized by sudden sideways deflection under compressive stress. It can happen even when the material's stress capacity hasn't been reached. It's a sudden loss of stability.
Bus – A road vehicle designed to carry many passengers. A common sight, a workhorse of public transportation.
Bushing – A type of vibration isolator, often made of rubber or polyurethane. It sits between two parts, damping vibrations and allowing controlled movement. Common in vehicle suspension systems.
Boiler – A closed vessel where a fluid, usually water, is heated. It's a fundamental component for water heating, central heating, and power generation.

C

CAD – See Computer-aided design.
CAM – See Computer-aided manufacturing.
CAID – See Computer-aided industrial design.
Calculator – An electronic device for performing calculations, from basic arithmetic to complex mathematics. Portable, and generally less prone to emotional errors than humans.
Calculus – The mathematical study of continuous change. It’s the language of motion, of growth, of decay.
Car handling – See Automobile handling.
Carbon fiber reinforced polymer – (CFRP) A strong, lightweight fiber-reinforced plastic made with carbon fibers. It combines the properties of its constituents for superior performance.
Carbon fibers – Fibers primarily composed of carbon atoms, known for their high stiffness, tensile strength, low weight, and resistance to heat and chemicals. They're valuable in demanding applications, though costly.
Classical mechanics – The physics of macroscopic objects. It describes the motion of everything from projectiles to planets. The foundational mechanics before the quantum realm intruded.
Clean room design – A method of recreating a design by reverse engineering without infringing on copyrights. It's about independent invention, a way to build something similar without stepping on legal toes.
Clevis fastener – A U-shaped bracket with a pin passing through it, used to connect or secure parts. Simple, effective, and widely used.
Clock – An instrument for measuring and indicating time. An ancient invention, essential for organizing human activity.
Clutch – A mechanical device that engages and disengages the transmission of power between rotating shafts. It’s the intermediary, the control point for power flow.
CNC – (Computer Numerical Control) The automated control of machining tools by computer. It allows for precise, programmed manufacturing without constant human intervention.
Coefficient of thermal expansion – A measure of how much the size of an object changes with temperature. It quantifies the material's response to heat.
Coil spring – A helical spring made of elastic material. Used to store and release energy, absorb shock, or maintain force. It returns to its original shape when unloaded.
Combustion – A high-temperature, exothermic chemical reaction between a fuel and an oxidant, usually oxygen. It produces heat, light, and byproducts like smoke.
Composite material – A material made from two or more constituent materials with different properties. When combined, they create a new material with characteristics superior to the individual components. It's the synergy of materials.
Compression ratio – The ratio of the volume of a combustion chamber at its largest to its smallest capacity. A key specification for internal and external combustion engines.
Compressive strength – A material's ability to withstand loads that tend to reduce its size, as opposed to tensile strength. It resists being squeezed.
Computational fluid dynamics – (CFD) A branch of fluid mechanics that uses numerical analysis and computers to simulate and solve problems involving fluid flows. It’s the digital modeling of liquids and gases in motion.
Computer – A device that can be instructed to perform sequences of arithmetic or logical operations automatically. The heart of modern automation and information processing.
Computer-aided design – (CAD) The use of computer systems to assist in the creation, modification, analysis, and optimization of designs. It enhances productivity and improves the quality of design documentation.
Computer-aided industrial design – (CAID) A subset of CAD focused on the aesthetic and functional aspects of a product’s look-and-feel.
Computer-aided manufacturing – (CAM) The use of software to control machine tools and other manufacturing equipment. It streamlines the production process.
Computer numerical control – (NC, CNC) The automated control of machining tools by computer instructions. It’s about programmed precision.
Conservation of mass – The principle that in a closed system, mass cannot be created or destroyed, only changed in form. It remains constant over time. A fundamental law.
Constant-velocity joint – (CV joint) A mechanical coupling that allows a drive shaft to transmit power through a variable angle at a constant rotational speed. Essential for modern front-wheel drive vehicles.
Constraint – (This entry is rather sparse, which is… typical. Constraints are the limitations, the boundaries that dictate how systems can behave.)
Continuum mechanics – A branch of mechanics that treats materials as continuous masses, rather than discrete particles. It’s used to analyze the behavior of deformable solids and fluids.
Control theory – A field of study focused on controlling dynamical systems using feedback. It aims for optimal control without delay or overshoot, ensuring stability.
Corrosion – The gradual destruction of materials, usually metals, through chemical or electrochemical reactions with their environment. It’s the inevitable decay, the return to a more stable form.
Cotter pin – A pin or wedge used to secure parts by passing through a hole. A simple, yet effective, fastening method.
Crankshaft – A mechanical component that converts reciprocating motion into rotational motion, or vice versa. It's the heart of many engines.
Cybernetics – (This entry is also remarkably brief. Cybernetics is the study of control and communication in animals and machines. It’s about feedback loops, about systems regulating themselves. Perhaps too complex for a simple definition.)

D

Damping ratio – A measure of how oscillations in a system die down over time. It quantifies the dissipation of energy. Too little damping, and it oscillates wildly; too much, and it’s sluggish.
Deformation (engineering) – The change in size or shape of an object under stress. Elastic deformation is reversible; plastic deformation is permanent. It’s the material’s response to force.
Delamination – A failure mode where a material fractures into layers. Common in composites and laminates. It’s the separation of the whole.
Design – (Another surprisingly brief entry. Design is the blueprint, the plan, the conceptualization of an object or system. It’s where intention meets form.)
Design for manufacturability – (DFM) The practice of designing products to be easily and cost-effectively manufactured. It’s about building with production in mind from the outset.
Diesel engine – An internal combustion engine where ignition occurs due to the heat generated by adiabatic compression of air. Named after Rudolf Diesel.
Differential – A gear train where the speed of one shaft is the average of the speeds of others. Crucial for allowing wheels to rotate at different speeds during a turn.
Dimensionless number – A quantity with no physical dimensions, often used in physics and engineering to simplify complex relationships. Examples include Reynolds number and Mach number.
Diode – A two-terminal electronic component that conducts current primarily in one direction. It’s a one-way street for electricity.
Diode laser – (A brief mention, suggesting a laser based on a semiconductor diode.)
Docking sleeve – (No definition provided. Likely a component used for coupling or connecting.)
Drafting – See Technical drawing.
Drifting – (A motorsport term, referring to a specific driving technique. Not a core mechanical engineering term, but a related application.)
Driveshaft – A component that transmits torque and rotation between parts that are separated or need to move relative to each other.
Dynamics (mechanics) – The branch of classical mechanics concerned with the study of forces and their effects on motion. It's about what makes things move.
Dynamometer – A device for measuring torque and rotational speed to calculate the power output of an engine or motor. It quantifies performance.

E

Elasticity – The ability of a material to resist deformation and return to its original shape when the applied forces are removed. It’s the inherent springiness of matter.
Electric current – A stream of charged particles, usually electrons, moving through a conductor. It’s the flow of electrical charge.
Electric motor – An electrical machine that converts electrical energy into mechanical energy. It uses magnetic fields and electric current to generate rotation.
Electrical engineering – The discipline concerned with the study, design, and application of equipment and systems that use electricity, electronics, and electromagnetism.
Electrical circuit – A closed loop that allows electric current to flow.
Electrical network – An interconnection of electrical components or a model thereof.
Electromagnetism – (A fundamental force, the interplay of electricity and magnetism. Its definition here is conspicuously absent, which is… disappointing.)
Electronic circuit – A circuit composed of individual electronic components connected by conductive pathways.
Electronics – (The field dealing with electronic circuits and devices. Its definition here is also missing, which feels like an oversight.)
Energy – (The fundamental capacity to do work. Its definition is elided, leaving a gaping hole in the foundational concepts.)
Engine – (The device that converts energy into mechanical work. Its own definition is absent. Remarkable.)
Engineering – The application of scientific principles to design and build structures, machines, and other items. It’s about practical application.
Engineering cybernetics – (The application of cybernetic principles to engineering problems. Again, a surprisingly brief mention.)
Engineering drawing – A technical drawing that communicates design information, including dimensions and tolerances. It’s a visual language for construction.
Engineering economics – The study of how to make engineering decisions regarding the allocation of limited resources. A practical application of microeconomics.
Engineering ethics – The examination of the obligations of engineers to society, clients, and the profession. It’s about responsibility.
Engineering management – The combination of technical expertise and management skills to oversee complex engineering operations.
Engineering society – A professional organization for engineers. They provide community, resources, and standards.
Exploratory engineering – The process of designing and analyzing hypothetical systems that might be feasible in the future, pushing the boundaries of current technology. It’s about envisioning what could be.

F

Fits and tolerances – (This entry is blank. A critical concept in mechanical engineering, referring to the allowable variation in dimensions for mating parts. Its absence is notable.)
Factor of safety – A multiplier applied to the expected load to ensure a structure or component can withstand more than its anticipated stress. It’s a margin for error, a safety net.
False precision – (This entry is also blank. It likely refers to presenting data with more precision than is actually justified.)
Fast fracture – (Blank. Refers to rapid crack propagation, a dangerous failure mode.)
Fatigue – The weakening of a material caused by repeatedly applied loads, even if those loads are below the material's yield strength. It’s the cumulative damage from cyclic stress.
Fillet – A rounded internal corner, often used to strengthen a part by reducing stress concentrations. It’s a subtle curve that prevents breakage.
First law of thermodynamics – The law of energy conservation. Energy can be converted from one form to another, but it cannot be created or destroyed.
Finite element analysis – (FEA) A computational method used to predict how a product reacts to real-world forces, vibration, heat, fluid flow, and other physical effects. It breaks down complex structures into smaller elements.
Flange – A projecting rim or edge, used to increase strength, facilitate attachment, or guide. Common in pipes and structural components.
Fluid mechanics – The study of fluids (liquids, gases, and plasmas) in motion and at rest, and the forces acting on them.
Flywheel – A rotating mechanical device used to store rotational energy. It smooths out power delivery by absorbing and releasing kinetic energy.
Force – An influence that can cause an object with mass to change its velocity, i.e., to accelerate. It has both magnitude and direction, making it a vector quantity.
Force density – (Blank. Likely refers to force per unit volume or mass.)
Forging – A manufacturing process involving the shaping of metal using localized compressive forces. It’s a method of plastic deformation.
Four-bar linkage – A common mechanical linkage consisting of four rigid bodies connected by hinges. It's a fundamental mechanism for converting motion.
Four-stroke cycle – The sequence of events in a reciprocating engine involving intake, compression, power, and exhaust strokes.
Four wheel drive – A drivetrain that engages all four wheels of a vehicle for propulsion.
Friction – The force that opposes the relative motion of surfaces in contact. It can be static (between stationary surfaces) or kinetic (between moving surfaces). It’s the resistance to motion.
Front wheel drive – A drivetrain configuration where only the front wheels are driven.
Fundamentals of Engineering exam – (FE exam) A standardized exam required for professional engineer licensure in the United States.
Fusible plug – A safety device in boilers designed to melt and release steam if the water level drops too low.
Fusion deposition modelling – A 3D printing process where material is deposited layer by layer. Also known as fused filament fabrication.

G

Gas compressor – A device that increases the pressure of a gas by reducing its volume.
Gauge – A measuring instrument for determining the size or amount of something.
Gear – A rotating mechanical component with teeth that mesh with another toothed part to transmit torque and alter speed. It’s a fundamental element of power transmission.
Gear coupling – A mechanical device that connects two shafts, allowing for misalignment while transmitting torque.
Gear ratio – The ratio of the pitch circles of mating gears, determining the speed and mechanical advantage of the gear set.
Granular material – (Blank. Refers to materials composed of discrete macroscopic particles, like sand or powders.)

H

Heat engine – A system that converts heat or thermal energy into mechanical energy. It's the basis of most power generation.
Heat transfer – The movement of thermal energy from one system to another.
Heating and cooling systems – Systems designed to control the temperature, humidity, and purity of the air in an enclosed space.
Hinge – A mechanism that allows a part to pivot around a fixed point.
Hoberman mechanism – (Blank. Likely a specific type of expanding or retracting mechanism.)
Hobson's joint – (Blank. Possibly a type of universal joint or coupling.)
Hooke's law – The principle that the force needed to extend or compress a spring by some amount is proportional to that distance. It describes elasticity.
Hotchkiss drive – A type of rear-wheel drive system in automobiles that uses leaf springs to locate the rear axle and transmit torque.
HVAC – Acronym for Heating, Ventilation, and Air Conditioning.
Hydraulics – The branch of fluid mechanics concerned with the behavior of liquids under pressure.
Hydrostatics – The branch of fluid mechanics concerned with fluids at rest.

I

Ideal machine – A theoretical machine with no energy losses due to friction or other inefficiencies. Its mechanical advantage is purely based on geometry.
Ideal mechanical advantage – The mechanical advantage of an ideal machine, calculated solely from the geometry of the machine.
Imperial College London – (A prominent university with strong engineering programs. Its inclusion here is a bit out of place for a technical glossary, but perhaps signifies an institution of note.)
Inclined plane – A simple machine consisting of a flat supporting surface tilted at an angle, with one end higher than the other. It reduces the force needed to lift an object.
Independent suspension – A type of vehicle suspension system where each wheel is mounted on its own arm and shock absorber, allowing it to move independently of the other wheels.
Inductor – An electronic component that stores energy in a magnetic field when electric current flows through it.
Industrial engineering – A branch of engineering focused on optimizing complex processes, systems, or organizations. It’s about efficiency and productivity.
Inertia – The resistance of any physical object to any change in its state of motion; this includes changes to its speed, direction, or state of rest. It’s the tendency to keep doing what it's doing.
Institution of Mechanical Engineers – (IMechE) A professional engineering institution based in the UK. Similar to ASME, but with a different geographical focus.
Instrumentation – The branch of science and technology concerned with the design and use of measuring instruments. It’s about measurement and control.
Integrated circuit – (IC) A set of electronic components etched onto a small piece of semiconductor material, forming a complex circuit.
Intelligent pump – (Blank. Suggests a pump with advanced control or diagnostic capabilities.)
Invention – A unique or novel device, method, or process. An inventor can sometimes secure a patent for their creation.

J

Jack chain – (Blank. Likely a specific type of chain used in lifting mechanisms.)
Jacking gear – (Blank. Mechanical system for lifting or raising something.)
JIC fitting – (Blank. Refers to fittings used in hydraulic systems, following Joint Industry Council standards.)
Joule – The SI unit of energy, work, or heat. Named after James Prescott Joule. It represents a specific amount of energy transfer.

K

Kelvin – The base SI unit of temperature. It uses absolute zero as its zero point.
Kinematic determinacy – (Blank. Refers to whether the motion of a mechanical system can be determined solely from its geometry and constraints.)
Kinematics – The branch of classical mechanics concerned with the study of motion without considering the forces that cause it. It's about how things move.

L

Laser – (Light Amplification by Stimulated Emission of Radiation. Its definition is missing, but it's a crucial technology in many fields.)
Leaf spring – A type of spring used for vehicle suspension, composed of several layers of metal strips.
Lever – A simple machine consisting of a rigid rod pivoted at a fulcrum. It amplifies input force to provide greater output force, achieving mechanical advantage.
Liability – (Blank. Refers to legal responsibility, relevant in engineering for product safety and design.)
Life cycle cost analysis – An assessment of the total cost of a product or system over its entire lifespan, from design to disposal.
Limit state design – A design philosophy where structures are designed to withstand critical conditions (limit states) during their intended service life.
Linkage – A system of interconnected rigid bodies (links) that are connected by joints and are used to transmit forces and motion.
Live axle – An axle that transmits power to the wheels.
Load transfer – The redistribution of forces within a structure or system when components are added or removed, or when external forces change.
Locomotive – A powered railcar that provides the motive power for a train.
Lubrication – The process of reducing friction, heat, and wear between moving surfaces by introducing a lubricant.

M

Machine – A device that uses mechanical energy to perform or assist in the performance of human tasks.
Machine learning – A subfield of artificial intelligence that enables systems to learn from data without explicit programming.
Machinery's Handbook – A comprehensive reference book for mechanical engineers and machinists, first published in 1914.
Magnetic circuit – (Blank. Refers to the path of magnetic flux in a magnetic device.)
Margin of safety – See Factor of safety.
Mass transfer – The net movement of anything across a boundary. In engineering, it often refers to the movement of chemical species.
Materials – The study of the properties of materials and their applications.
Materials engineering – A discipline focused on the discovery, understanding, and application of materials.
Material selection – The process of choosing the most appropriate material for a specific application based on its properties and requirements.
Mechanical advantage – The ratio of output force to input force in a simple machine or mechanism. It indicates how much the machine amplifies the input force.
Mechanical biological treatment – (Blank. Likely a waste treatment process combining mechanical and biological methods.)
Mechanical efficiency – The ratio of useful output work to input work in a mechanical system. It accounts for energy losses.
Mechanical engineering – The discipline that deals with the design, construction, and use of machines. It's about the tangible world of moving parts.
Mechanical equilibrium – A state where the net force and net torque acting on an object are zero, resulting in no change in its state of motion.
Mechanical work – The energy transferred when a force causes displacement. Defined as Force × Displacement.
Mechanics – The branch of physics that studies force and motion.
Mechanochemistry – The study of chemical reactions that are initiated or influenced by mechanical forces.
Mechanosynthesis – (Blank. The synthesis of molecules using mechanical energy.)
Mechatronics – The synergistic integration of mechanical engineering, electronics, control theory, and computer science.
Microelectromechanical systems – (MEMS) Devices that integrate mechanical and electrical components on a microscopic scale.
Micromachinery – (Blank. Refers to machinery operating at microscopic scales.)
Microprocessor – A central processing unit (CPU) on a single integrated circuit or chip.
Microtechnology – Technology operating at microscopic scales.
Modulus of rigidity – A measure of a material's resistance to shear deformation. Also known as the shear modulus.
Molecular assembler – (Blank. A hypothetical nanotechnological device capable of constructing molecular structures.)
Molecular nanotechnology – (Blank. Nanotechnology involving the manipulation of individual molecules.)
Moment – A measure of the effect of a force acting at a distance from a point or axis. Often referred to as torque.
Moment of inertia – A measure of an object's resistance to changes in its rotational state of motion. It depends on mass and its distribution.
Motorcycle – A two-wheeled motor vehicle.
Multi-link suspension – A complex vehicle suspension system using multiple control arms to provide precise wheel control.

N

Nanotechnology – The manipulation of matter on an atomic, molecular, and supramolecular scale.
Newton (unit) – The SI unit of force. Defined as the force required to accelerate a mass of 1 kilogram at a rate of 1 metre per second squared. Named after Isaac Newton.
Normal stress – The stress component acting perpendicular to a surface.
Nozzle – A device that increases the velocity of a fluid by decreasing its cross-sectional area.

O

Ohm's law – The relationship between voltage, current, and resistance in an electrical circuit. V = IR.
Orientation – (Blank. Refers to the position or direction of an object.)
Overdrive – A gear ratio where the output shaft rotates faster than the input shaft, typically used to reduce engine speed at higher road speeds.
Oversteer – A vehicle handling characteristic where the rear wheels lose traction before the front wheels during a turn, causing the vehicle to rotate outwards.

P

Pascal (unit) – The SI unit of pressure, defined as one newton per square metre.
Physics – The natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force.
Pinion – A small gear that meshes with a larger gear or a rack.
Piston – A component that moves back and forth within a cylinder in engines and pumps.
Pitch drop experiment – A long-term experiment demonstrating the high viscosity of pitch, a fluid that appears solid.
Plain bearing – A bearing that relies on sliding motion between surfaces, often with lubrication.
Plasma processing – (Blank. Uses plasma to modify material surfaces.)
Plasticity – The ability of a material to undergo permanent deformation without fracturing.
Pneumatics – The branch of fluid mechanics concerned with the behavior of gases under pressure.
Poisson's ratio – The negative ratio of transverse strain to axial strain in the elastic deformation of a material.
Position vector – A vector that describes the position of a point relative to an origin.
Potential difference – See Voltage.
Power – The rate at which energy is transferred or converted. A scalar quantity.
Power stroke – The phase in an internal combustion engine where combustion drives the piston downwards.
Pressure – Force applied perpendicular to a surface per unit area.
Process control – The use of control systems to manage and regulate industrial processes.
Product lifecycle management – The process of managing the entire lifecycle of a product from inception, through engineering design and manufacture, to service and disposal.
Professional engineer – (PE) A licensed engineer in the United States who has passed the Principles and Practice of Engineering exam.
Project management – The discipline of initiating, planning, executing, controlling, and closing the work of a team to achieve specific goals and meet specific success criteria.
Pulley – A simple machine consisting of a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power.
Pump – A device that moves fluids (liquids or gases) by mechanical action.

Q

Quality – (Blank. Refers to the standard of something as measured against other things of a similar kind; the degree of excellence.)
Quality control – A process by which a company checks the quality of its products or services.
Quality assurance – A process-oriented way of preventing defects by making sure that established processes are being followed.

R

Rack and pinion – A mechanism that converts rotational motion into linear motion, or vice versa.
Rack railway – A railway with a toothed rack rail, usually between the two running rails, allowing trains to climb steep gradients.
Railcar – A railroad car, especially one that is self-propelled.
Rail gauge – The spacing of the rail tracks on a railway.
Railroad car – A vehicle used for carrying passengers or freight on a railway.
Railroad switch – A mechanism enabling trains to be diverted from one track to another. Also known as a points.
Rail tracks – The permanent way on which railway vehicles run.
Random vibration – Vibration that is unpredictable in amplitude and frequency over time.
Reaction kinetics – The study of the rates of chemical reactions.
Rear wheel drive – A drivetrain configuration where only the rear wheels are driven.
Refrigeration – The process of removing heat from a space or substance.
Reliability engineering – The discipline that applies scientific and engineering principles to the design, development, and operation of systems, ensuring they perform their intended functions without failure for a specified period.
Relief valve – A safety device designed to protect pressure vessels or systems from over-pressurization.
RepRap Project – A project to develop a free, open-source 3D printer that can print its own plastic components.
Resistive force – See Friction.
Resistor – An electronic component that impedes the flow of electric current.
Reverse engineering – The process of deconstructing a device or system to understand its design, function, or operation.
Rheology – The study of the flow of matter, primarily in the liquid state, but also as soft solids or solids under conditions in which they respond as a viscous fluid.
Rigid body – An idealized object that does not undergo any deformation when subjected to forces.
Robotics – The branch of mechanical engineering, electrical engineering, computer science, and artificial intelligence concerned with the design, construction, operation, and application of robots.
Roller chain – A type of chain used to transmit mechanical power between two gears.
Rolling – A manufacturing process where metal is passed through rollers to reduce its thickness or impart a desired shape.
Rotordynamics – The study of the dynamics of rotating machinery, such as turbines and rotors.
Rube Goldberg machine – A deliberately complex contraption designed to perform a simple task in an overly elaborate way.

S

Safety engineering – The application of engineering principles to prevent or mitigate hazards and accidents.
Screw theory – (Blank. Mathematical theory describing the motion of rigid bodies.)
Seal – A device or material used to prevent the leakage of fluids or gases between two mating surfaces.
Second law of thermodynamics – States that the total entropy of an isolated system can only increase over time, or remain constant in ideal cases where the system is in a steady state or undergoing a reversible process. It implies that energy transformations are never 100% efficient.
Semiconductor – A material with electrical conductivity between that of a conductor and an insulator.
Series and parallel circuits – Ways of connecting electrical components in a circuit.
Shear force – A force acting parallel to a surface.
Shear pin – A safety device designed to break when subjected to excessive shear force, protecting machinery.
Shear strength – A material's ability to withstand shear stress.
Shear stress – Stress acting parallel to a surface.
Simple machine – A basic mechanical device that changes the direction or magnitude of a force. Examples include levers, pulleys, and inclined planes.
Simulation – The imitation of the operation of a real-world process or system over time.
Slide rule – A mechanical analog computer used for performing calculations.
Society of Automotive Engineers – (SAE) A professional organization that develops standards for the automotive industry.
Solid mechanics – The branch of mechanics concerned with the mechanical behavior of solid materials.
Solid modeling – A type of 3D computer graphics model that represents the volume of an object.
Split nut – (Blank. A nut that can be opened to engage with a threaded shaft.)
Sprung mass – The part of a vehicle's mass supported by the suspension system.
Statics – The branch of mechanics concerned with the analysis of loads (forces) on non-accelerating objects. It’s about equilibrium.
Steering – The system used to control the direction of a vehicle.
Stress–strain curve – A graph illustrating the relationship between stress and strain in a material.
Structural failure – The collapse or inability of a structure to perform its intended function due to applied loads.
Student Design Competition – (Blank. Refers to competitions where students design and build engineering projects.)
Surveying – The technique and science of accurately determining the terrestrial or three-dimensional positions of points and the distances and angles between them.
Suspension – The system of springs, shock absorbers, and linkages that connects a vehicle to its wheels, allowing for relative motion.
Switch – An electrical component that can disconnect or connect the conducting path in an electrical circuit.

T

Technical drawing – The creation of drawings that visually communicate how something functions or is constructed. It uses a standardized visual language.
Technology – The application of knowledge for practical purposes, and the tools and systems resulting from it.
Tensile strength – The maximum stress a material can withstand while being stretched before breaking.
Tensile stress – Stress acting to stretch or elongate a material.
Testing adjusting balancing – (TAB) A phase in the commissioning of HVAC systems to ensure proper performance.
Theory of elasticity – A branch of continuum mechanics that studies the behavior of elastic solids under stress.
Thermodynamics – The branch of physics that deals with heat, work, temperature, and their relation to energy and entropy. It's governed by the four laws of thermodynamics.
Third law of thermodynamics – States that the entropy of a system approaches a constant value as its temperature approaches absolute zero.
Toe – (Blank. Refers to the angle of the front wheels relative to the vehicle's longitudinal axis.)
Torque – A twisting or turning force. It's the rotational equivalent of linear force.
Torsion beam suspension – A type of vehicle suspension where the suspension arms are connected by a torsion beam.
Torsion spring – A spring that works by twisting or untwisting.
Toughness – A material's ability to absorb energy and deform plastically before fracturing. It's resistance to fracture when stressed.
Track gauge – The spacing between the rails on a railway.
Transmission – A mechanical system used to transfer power from a source to a load, often with the ability to change speed and torque.
Truck – A motor vehicle designed primarily for transporting goods.
Truck (railway) – The chassis assembly beneath a railway vehicle that holds the wheelsets. Also known as a bogie.
Turbine – A rotary mechanical device that extracts energy from a fluid flow and converts it into useful work.
Tribology – The science and engineering of interacting surfaces in relative motion, including the study and application of the principles of friction, lubrication, and wear.
Touch screen – An electronic visual display that can detect the presence and location of a touch within the display area.
tear – (Blank. Refers to the process of ripping or splitting material.)
Tire manufacturing – (Blank. The process of creating vehicle tires.)

U

Understeer – A vehicle handling characteristic where the front wheels lose traction before the rear wheels during a turn, causing the vehicle to resist turning.
Unibody – A vehicle construction method where the body and chassis are combined into a single structure.
Unsprung weight – The mass of the vehicle components not supported by the suspension system, such as wheels, tires, brakes, and axles. Lower unsprung weight generally improves handling.

V

Verification and Validation – (Blank. Crucial processes in engineering to ensure a system is built correctly (verification) and meets its intended purpose (validation).)
Valve – A device that regulates, directs, or controls the flow of a fluid by opening, closing, or partially obstructing passageways.
Vector – A geometric object that has both magnitude and direction. It’s a quantity with size and orientation.
Vertical strength – (Blank. Refers to the ability of a structure or component to withstand vertical loads.)
Viscosity – A measure of a fluid's resistance to flow.
Volt – The SI unit of electric potential difference or voltage. Named after Alessandro Volta.
Vibration – A mechanical oscillation around an equilibrium point.
Velocity diagrams – (Blank. Diagrams used in kinematics to represent velocities of different parts of a mechanism.)

W

Wear – The gradual removal or deformation of material from solid surfaces due to mechanical or chemical interactions. It’s the consequence of friction and abrasion.
Wedge – A triangular tool, a portable inclined plane. It converts force into pressure to split or hold objects.
Weight transfer – The shift of weight distribution within a vehicle during acceleration, braking, or cornering.
Wheel – A circular component that rotates around an axle, used for transportation or as part of a machine.
Wheel and axle – A simple machine consisting of a wheel attached to a smaller axle, rotating together.
Wheelset – The wheel–axle assembly of a railroad car.
Work – The energy transferred when a force causes displacement. It’s the application of force over a distance.

X

X bar charts – (Blank. Likely refers to control charts used in quality control.)

Y

Yield point – The point on a stress–strain curve where a material begins to deform plastically. Below this point, deformation is elastic; above it, it's permanent.
Yield strength – The stress at which a material begins to deform plastically. It's a critical parameter for determining maximum allowable loads.
Young's modulus – (E) A measure of a solid material's stiffness in tension or compression. It quantifies the relationship between stress and strain in the linear elastic region. Expressed in gigapascals (GPa).

Z

Zero defects – A management philosophy aimed at eliminating defects in production. It was popular in the mid-20th century and saw a resurgence later.
Zeroth Law of Thermodynamics – If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. It establishes the concept of temperature.

Glossary Of Mechanical Engineering

Contents

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

See also