View source for Engineering:Reciprocating motion

{{short description|Repetitive back-and-forth linear motion}}
[[Image:Steam engine in action.gif|thumb|Double-acting [[Engineering:Stationary steam engine|stationary steam engine]] demonstrating conversion of reciprocating motion to rotary motion. The piston is on the left, the crank is mounted on the flywheel axle on the right]]
[[File:Rotary to Reciprocating Motion.gif|thumb|Machine demonstrating conversion of rotary motion to reciprocating motion using gears.  The bottom pair of gears drives the mechanism]]

'''Reciprocating motion''', also called '''reciprocation''', is a repetitive up-and-down or back-and-forth linear [[Physics:Motion|motion]]. It is found in a wide range of mechanisms, including [[Engineering:Reciprocating engine|reciprocating engine]]s and [[Engineering:Pump|pump]]s. The two opposite motions that comprise a single reciprocation cycle are called [[Engineering:Stroke (engine)|stroke]]s.{{Citation needed|date=September 2010}}

A [[Engineering:Crank (mechanism)|crank]] can be used to convert into reciprocating motion, or conversely turn reciprocating motion into circular motion.{{citation needed|date=May 2022}}

For example, inside an [[Earth:Internal combustion engine|internal combustion engine]] (a type of reciprocating engine),  the expansion of burning fuel in the [[Physics:Cylinder (engine)|cylinder]]s periodically pushes the [[Engineering:Piston|piston]] down, which, through the [[Engineering:Connecting rod|connecting rod]], turns the [[Engineering:Crankshaft|crankshaft]]. The continuing rotation of the crankshaft drives the piston back up, ready for the next cycle. The piston moves in a reciprocating motion, which is converted into circular motion of the crankshaft, which ultimately propels the vehicle or does other useful work.{{Citation needed|date=May 2022}}

The reciprocating motion of a pump piston is close to, but different from, [[Physics:Sine wave|sinusoidal]] [[Physics:Simple harmonic motion|simple harmonic motion]]. Assuming the wheel is driven at a perfect constant rotational velocity, the point on the crankshaft which connects to the connecting rod rotates smoothly at a constant velocity in a circle. Thus, the displacement of that point, is indeed  exactly sinusoidal by definition.  However, during the cycle, the angle of the connecting rod changes continuously. So, the horizontal displacement of the "far" end of the connecting rod (i.e., connected to the piston) differs slightly from sinusoidal.  Circumstances where the wheel is not spinning with perfect constant rotational velocity, such as a steam locomotive starting up from a stop, are very much not sinusoidal.{{Citation needed|date=May 2022}} So basically a up and down a repetitive up-and-down or back-and-forth linear motion.

==See also==
*{{annotated link|Oscillation}}
*{{annotated link|Engineering:Stroboscope}}
*{{annotated link|Engineering:Reciprocating saw}}
*{{annotated link|Engineering:Reciprocating engine}}
*{{annotated link|Engineering:Rotary saw|Rotary reciprocating saw}}
*{{annotated link|Engineering:Agitator (device)|Agitation}}
*{{annotated link|Engineering:Scotch yoke}}
*{{annotated link|Engineering:Crank (mechanism)|Crank}}
*{{annotated link|Engineering:Crankshaft}}
*{{annotated link|Engineering:Swashplate}}
*{{annotated link|Engineering:Trip hammer}}
*{{annotated link|Engineering:Slider-crank linkage}}
*{{annotated link|Physics:Straight line mechanism}}
*{{annotated link|Engineering:Reciprocating compressor}}
*{{annotated link|Engineering:Sun and planet gear}}

==References==

{{reflist}}

[[Category:Mechanical engineering]]



{{Sourceattribution|Reciprocating motion}}