Mechanical engineering

A gear wheel that revolves around the wheel with which it meshes, in an epicyclic train.

A polygonal figure the sides of which are vectors representing several forces acting simultaneously upon one point, so that the vector necessary to make the figure closed is the resultant of those forces.

polyspast

A windlass with many pulleys and truckles

poppet valve

A valve (as in an internal combustion engine) which consists of a sliding shaft with a disk on the end (the disk being shaped to alternately plug and unplug a matching port). Such a valve is opened by either a cam or a solenoid and is closed by either a spring or a solenoid.

postmechanical

Occurring after a mechanical process has completed.

power

A measure of the effectiveness that a force producing a physical effect has over time. If linear, the quotient of: (force multiplied by the displacement of or in an object) ÷ time. If rotational, the quotient of: (force multiplied by the angle of displacement) ÷ time.

press

To activate a button or key by exerting a downward or forward force on it, and then releasing it.

pump valve

A mechanical device that controls the flow of fluids through a pump and its associated pipes.

pushrod

A rigid reciprocating rod that, by its movement, transmits force to actuate a mechanism.

quill

A quill drive, having a hollow shaft with another movable shaft inside it.

race rotation

The rotation of the inner and outer parts of a bearing race.

rack

A bar with teeth on its face or edge, to work with a pawl as a ratchet allowing movement in one direction only, used for example in a handbrake or crossbow.

radial shaft seal

A seal for any rotary element.

radiator

A device that lowers engine coolant temperature by conducting heat to the air, through metal fins.

RCP

Initialism of reinforced concrete pipe.

rebat

To perform a rebatment; to rotate one orthographic view into the plane of another orthographic view along the line of intersection between the two planes.

reduction drive

A device which reduces the input rotational speed to a lower output speed, and can also increase torque.

resistance distance

In classical mechanics, the distance from the resistance (on a lever) to the fulcrum.

retaining valve

A device that retains some air pressure in a train's air brake cylinders even when the automatic brake valve is set to the fully-released position, used on steep downgrades to allow a degree of continuous braking effort to be maintained without depleting the pressure in the train's brakepipe (which would result in the loss of nearly all braking ability, causing a runaway).

retarder

A device for slowing down large trucks, lorries, buses, shunted railway wagons.

return spring

The spring that returns a door handle or knob to its original position when rotated.

reverse gear

A gear (setting) in a vehicle's transmission which, when selected, makes the vehicle move backward. (Denoted with symbol R on a shifter's labeling.)

rocker arm

A valvetrain component that typically transfers the motion of a pushrod in an overhead valve internal combustion engine to the corresponding intake or exhaust valve.

rodding

A system of rods etc. used for movement.

run-in

(sometimes comparable) Having been run in to seat the parts.

runout

Deviation of the axis of rotation of a rotating object (especially a milling cutter or workpiece) relative to that object's centerline; the specific amount of deviation.

safety

A safety lock or safety catch: a mechanism on a weapon or dangerous equipment designed to prevent accidental firing or operation.

screw box

A device, resembling a die, made of a type of spindle, for cutting the thread on a wooden screw.

screw theory

The algebraic calculation of pairs of vectors, such as linear and angular velocity, that arise in the kinematics of rigid bodies.

seating

Collectively, the various fitted supports of the parts of a structure or of a machine; a housing in which a component is seated.

self-clamp

Of a clamp or other mechanism, that tightens or secures itself automatically, often without needing separate adjustment.

self-right

To make oneself upright.

semi-trailing

Having a movement that pivots on an access which is at an angle between longitudinal and transverse.

shaft horsepower

In an engine, the power measured in horse power delivered to a rotating shaft, which could be in a turbine, or transmission.

shear centre

The point where a shear force can act without producing any twist in the section. In general not the centroid, but a point through which a force transverse to the axis of a beam section can act and not cause any twisting of the beam section.

ship lift

A device consisting of a structural platform which can be used to launch ships by lowering them into the water, or to lift them into dry dock.

shock

A shock absorber (typically in the suspension of a vehicle).

shock absorber

A mechanical device designed to smooth out or damp any sudden shock impulse and dissipate kinetic energy; usually consists of a combination of a spring and a dashpot.

SI

Initialism of spark ignition.

side play

Lateral freedom of movement in moving parts.

simple harmonic motion

oscillating motion (as of a pendulum) in which the acceleration of the oscillator has an equal magnitude but opposite direction to the displacement of it from the equilibrium position.

skew bevel gear

A bevel gear in which the teeth are slanted, forming a spiral-like shape.

skirt finger

An individual, replaceable, flexible tube or flap attached to the bottom edge of the main inflatable skirt of a hovercraft or air cushion vehicle.

sleep

To spin on its axis with no other perceptible motion.

spin

An abnormal condition in journal bearings where the bearing seizes to the rotating shaft and rotates inside the journal, destroying both the shaft and the journal.

sprocket

A toothed wheel that enmeshes with a chain or other perforated band.

spur gear

The simplest type of gear wheel, with teeth projecting radially, parallel to its axis.

squirrel-cage motor

A kind of induction motor that harnesses electromagnetism in order to generate motion.

stub axle

An axle supporting only one wheel of a pair on opposite sides of a vehicle.

swivel

A piece, such as a ring or hook, attached to another piece by a pin, in such a manner as to permit rotation about the pin as an axis.

T-beam

A structural member with a cross section shaped like the letter T.

tackle block

A pulley over which a rope runs.

tap

A cylindrical tool used to cut an internal screw thread in a hole, with cutting edges around the lower end and an upper end to which a handle is fitted to turn the tool.

teleassistance

Assistance provided by means of a telecommunication system.

time history

A technique used in the field of structural dynamics to evaluate the behavior of structures under different loads and conditions, involving simulating the actual loads that a structure will experience over time.

top dead center

The reference mark on a flywheel (and engine block) indicating the engine is in this position, when aligned.

torque

To make something rotate about an axis by imparting torque to it.

torque converter

A device that converts the rotational output of a prime mover into work by driving a rotational load. A torque converter functions as a clutch and reduction gear, usually inside an automatic transmission, to allow loose coupling between the driver and the driven, letting the drive (such as a motor or engine) rotate at different speeds from the load (such as a wheel).

torsion