Swashplate

# Swashplate

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A swashplate is a device used in mechanical engineering
Mechanical engineering
Mechanical engineering is a discipline of engineering that applies the principles of physics and materials science for analysis, design, manufacturing, and maintenance of mechanical systems. It is the branch of engineering that involves the production and usage of heat and mechanical power for the...

to translate the motion of a rotating shaft into reciprocating motion
Reciprocating motion
Reciprocating motion, also called reciprocation, is a repetitive up-and-down or back-and-forth motion. It is found in a wide range of mechanisms, including reciprocating engines and pumps. The two opposite motions that comprise a single reciprocation cycle are called strokes...

, or to translate a reciprocating motion into a rotating one to replace the crankshaft
Crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

in engine designs.

## Construction

A swashplate consists of a disk attached to a shaft. If the disk is aligned squarely on the shaft then rotation of the shaft will turn the disk with it and no swashplate effect will be seen. Even a slight displacement of the disk from the square position, however, will cause the disk edge to appear to describe an oscillating linear path when viewed from a non-rotating point of view away from the shaft. The greater the angle of the plate to the shaft the more exaggerated the apparent linear motion will be. The apparent linear motion can be turned into an actual linear motion by having a follower, stationary with respect to the shaft but which presses against the top or bottom edge of the plate. The device has many similarities to the cam
Cam
A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path...

.

The swashplate engine
Swashplate engine
A swashplate engine, also called a barrel engine, is one type of axial engine. Swashplate engines are a type of reciprocating engine that replaces the common crankshaft with a circular swashplate which rotates....

uses a swashplate in place of a crankshaft to translate the motion of a piston into rotary motion. Internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s and Stirling engine
Stirling engine
A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work....

s have been built using this mechanism.

The axial piston pump
Axial piston pump
An axial piston pump is a positive displacement pump that has a number of pistons in a circular array within a cylinder block. It can be used as a stand-alone pump, a hydraulic motor or an automotive air conditioning compressor.-Description:...

drives a series of pistons aligned coaxially with a shaft through a swashplate to pump a fluid.

A helicopter swashplate
Swashplate (helicopter)
A swashplate is a device that translates input via the helicopter flight controls into motion of the main rotor blades. Because the main rotor blades are spinning, the swashplate is used to transmit three of the pilot's commands from the non-rotating fuselage to the rotating rotor hub and...

is a pair of plates, one rotating and one fixed, that are centered on the main rotor shaft. The rotating plate is linked to the rotor head, and the fixed plate is linked to the operator controls. Displacement of the alignment of the fixed plate is transferred to the rotating plate, where it becomes reciprocal motion of the rotor blade linkages. This type of pitch control, known as cyclic pitch, allows the helicopter rotor to provide selective lift in any direction.

Nutating flowmeters and pumps have similar motions to the wobble of a swashplate, but do not necessarily transform the motion to a reciprocating motion at any time.

Active Electronically Scanned Array
Active Electronically Scanned Array
An Active Electronically Scanned Array , also known as active phased array radar is a type of phased array radar whose transmitter and receiver functions are composed of numerous small solid-state transmit/receive modules . AESAs aim their "beam" by broadcasting radio energy that interfere...

(AESA) radars are flat plates that can scan up to sixty degrees in any direction from directly ahead of them. By mounting an AESA radar on a swashplate, the swashplate angle is added to the electronic scan angle. The typical swashplate angle chosen for this application is 40 degrees so the radar can scan a total angle of 200 degrees out of 360.