1 Linear Actuators

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ME0306 FLUID POWER CONTROL

III Year VI Sem

Department of Mechanical

Engineering

SRM UNIVERSITY


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Dierence Between Pump an

!ctuator

Pump perform" the function ofaing energ# to the $ui of ah#raulic "#"tem for tran"mi""ion to

"ome other location%

raulic actuator 'c#liner"(motor") *u"t o the oppo"ite%

The# e+tract energ# from the $uian con,ert it to mechanical energ#to perform u"eful wor-%


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Hydraulic cylinder ' al"o calle a"linear actuator") e+ten an retract a

pi"ton ro to pro,ie pu"h or pullforce to ri,e the e+ternal loa along"traight line path%

Hydraulic motors 'al"o calle rotar#actuator") rotate a "haft to pro,ie a

tor.ue to ri,e the loa along arotar# path%


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/inear actuator


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Types of Hydrauli Cyli!dersHydraulic cylinders are of the following types:

Single-acting cylinders.

Double-acting cylinders.Telescopic cylinders.

Tandem cylinders.

Single-Acting Cylinders


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1.Double-acting cylinder with a piston rod on one side.


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2.Double-acting cylinder with a piston rod on both sides

Double-rod cylinders can withstand higher side loads because

they have an etra bearing! one on each rod! to withstand the

loading! same wor" can be done on both side of the rod


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Telescopic Cylinder


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# telescopic cylinder is used when a long stro"e length and a

short retracted length are re$uired.

Telescopic cylinders are designed with a series of steel or

aluminum tubes of progressively smaller diameters nestedwithin each other.

The largest diameter sleeve is called the main or barrel. The

smaller inner sleeves are called the stages.

The smallest stage is often called the plunger or piston rod.The cylinders are usually mounted in machinery by pivot

mounts to the end or outer body of the barrel as well as on the

end of the plunger.


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P 0 1 2 ! large area

P 0 3444 'N) 2 5344'mm6)

P 0 4%7777 N8 mm6 ' 7%7 9ar)

P 0 1 2 ! Small area

P 0 3444 'N) 2 7644 'mm6)

P 04%:47 N8 mm6 ' : 9ar)


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Tanem air c#liner;Two c#liner" are a""em9le in "erie" in

orer to ou9le the force output%


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There are two c#liner" which are

connecte together in "uch a wa# thatthe pi"ton ro of one c#liner pu"he"through the 9ottom of the otherc#liner to it" pi"ton area%

B# u"ing thi" arrangement the area"are ae together an large force"ma# 9e tran"ferre for relati,el# "mall

e+ternal iameter" without increa"ingthe operating pre""ure%


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&ea,

#loa


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=#liner =u"hioning

The fluid is normally epelled through the outlet port direct but when the cushioning boss enters the recess the fluid

around the piston is trapped!

The only way the fluid can escape is through the secondary

path which is restricted by a needle valve.

The needle valve is ad%usted so that the piston is slowed up

over the the last part of its stro"e by a pressure build up in the

fluid escaping past the needle valve.


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G hi l b l f diff t li t t


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Graphical symbols of different linear actuators


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C linder Force Velocit


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Cylinder Force, Velocity


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&orce and velocity during etension stro"e:

'elocity vet( )in * #p&orce &

et

( p #p

&orce and velocity during retraction stro"e

'elocity

&orce

1 Linear Actuators

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