<s>
A	O
linear	B-Algorithm
actuator	I-Algorithm
is	O
an	O
actuator	B-Algorithm
that	O
creates	O
motion	O
in	O
a	O
straight	O
line	O
,	O
in	O
contrast	O
to	O
the	O
circular	O
motion	O
of	O
a	O
conventional	O
electric	O
motor	O
.	O
</s>
<s>
Linear	B-Algorithm
actuators	I-Algorithm
are	O
used	O
in	O
machine	O
tools	O
and	O
industrial	O
machinery	O
,	O
in	O
computer	O
peripherals	O
such	O
as	O
disk	O
drives	O
and	O
printers	O
,	O
in	O
valves	O
and	O
dampers	O
,	O
and	O
in	O
many	O
other	O
places	O
where	O
linear	O
motion	O
is	O
required	O
.	O
</s>
<s>
Mechanical	O
linear	B-Algorithm
actuators	I-Algorithm
typically	O
operate	O
by	O
conversion	O
of	O
rotary	B-Algorithm
motion	I-Algorithm
into	O
linear	O
motion	O
.	O
</s>
<s>
Screw	O
:	O
leadscrew	O
,	O
screw	O
jack	O
,	O
ball	B-Algorithm
screw	I-Algorithm
and	O
roller	O
screw	O
actuators	B-Algorithm
all	O
operate	O
on	O
the	O
principle	O
of	O
the	O
simple	O
machine	O
known	O
as	O
the	O
screw	O
.	O
</s>
<s>
By	O
rotating	O
the	O
actuator	B-Algorithm
's	O
nut	O
,	O
the	O
screw	O
shaft	O
moves	O
in	O
a	O
line	O
.	O
</s>
<s>
Wheel	O
and	O
axle	O
:	O
Hoist	B-Algorithm
,	O
winch	O
,	O
rack	O
and	O
pinion	O
,	O
chain	O
drive	O
,	O
belt	O
drive	O
,	O
rigid	B-Algorithm
chain	I-Algorithm
and	O
rigid	B-Algorithm
belt	I-Algorithm
actuators	I-Algorithm
operate	O
on	O
the	O
principle	O
of	O
the	O
wheel	O
and	O
axle	O
.	O
</s>
<s>
Cam	B-Data_Structure
:	O
Cam	B-Algorithm
actuators	I-Algorithm
function	O
on	O
a	O
principle	O
similar	O
to	O
that	O
of	O
the	O
wedge	O
,	O
but	O
provide	O
relatively	O
limited	O
travel	O
.	O
</s>
<s>
As	O
a	O
wheel-like	O
cam	B-Data_Structure
rotates	O
,	O
its	O
eccentric	O
shape	O
provides	O
thrust	O
at	O
the	O
base	O
of	O
a	O
shaft	O
.	O
</s>
<s>
Some	O
mechanical	O
linear	B-Algorithm
actuators	I-Algorithm
only	O
pull	O
,	O
such	O
as	O
hoists	B-Algorithm
,	O
chain	O
drive	O
and	O
belt	O
drives	O
.	O
</s>
<s>
Others	O
only	O
push	O
(	O
such	O
as	O
a	O
cam	B-Algorithm
actuator	I-Algorithm
)	O
.	O
</s>
<s>
Mechanical	O
actuators	B-Algorithm
typically	O
convert	O
rotary	B-Algorithm
motion	I-Algorithm
of	O
a	O
control	O
knob	O
or	O
handle	O
into	O
linear	O
displacement	O
via	O
screws	O
and/or	O
gears	O
to	O
which	O
the	O
knob	O
or	O
handle	O
is	O
attached	O
.	O
</s>
<s>
A	O
jackscrew	O
or	O
car	O
jack	O
is	O
a	O
familiar	O
mechanical	O
actuator	B-Algorithm
.	O
</s>
<s>
Another	O
family	O
of	O
actuators	B-Algorithm
are	O
based	O
on	O
the	O
segmented	O
spindle	O
.	O
</s>
<s>
Mechanical	O
actuators	B-Algorithm
are	O
also	O
frequently	O
used	O
in	O
the	O
field	O
of	O
lasers	O
and	O
optics	O
to	O
manipulate	O
the	O
position	O
of	O
linear	O
stages	O
,	O
rotary	O
stages	O
,	O
mirror	O
mounts	O
,	O
goniometers	O
and	O
other	O
positioning	O
instruments	O
.	O
</s>
<s>
Some	O
actuators	B-Algorithm
include	O
an	O
encoder	O
and	O
digital	O
position	O
readout	O
.	O
</s>
<s>
Hydraulic	O
actuators	B-Algorithm
or	O
hydraulic	O
cylinders	O
typically	O
involve	O
a	O
hollow	O
cylinder	O
having	O
a	O
piston	O
inserted	O
in	O
it	O
.	O
</s>
<s>
A	O
familiar	O
example	O
of	O
a	O
manually	O
operated	O
hydraulic	O
actuator	B-Algorithm
is	O
a	O
hydraulic	O
car	O
jack	O
.	O
</s>
<s>
Typically	O
though	O
,	O
the	O
term	O
"	O
hydraulic	O
actuator	B-Algorithm
"	O
refers	O
to	O
a	O
device	O
controlled	O
by	O
a	O
hydraulic	O
pump	O
.	O
</s>
<s>
Pneumatic	O
actuators	B-Algorithm
,	O
or	O
pneumatic	O
cylinders	O
,	O
are	O
similar	O
to	O
hydraulic	O
actuators	B-Algorithm
except	O
they	O
use	O
compressed	O
air	O
to	O
generate	O
force	O
instead	O
of	O
a	O
liquid	O
.	O
</s>
<s>
Air	O
actuators	B-Algorithm
are	O
not	O
necessarily	O
used	O
for	O
heavy	O
duty	O
machinery	O
and	O
instances	O
where	O
large	O
amounts	O
of	O
weight	O
are	O
present	O
.	O
</s>
<s>
One	O
of	O
the	O
reasons	O
pneumatic	O
linear	B-Algorithm
actuators	I-Algorithm
are	O
preferred	O
to	O
other	O
types	O
is	O
the	O
fact	O
that	O
the	O
power	O
source	O
is	O
simply	O
an	O
air	O
compressor	O
.	O
</s>
<s>
Because	O
air	O
is	O
the	O
input	O
source	O
,	O
pneumatic	O
actuators	B-Algorithm
are	O
able	O
to	O
be	O
used	O
in	O
many	O
places	O
of	O
mechanical	O
activity	O
.	O
</s>
<s>
Pneumatic	O
linear	B-Algorithm
actuators	I-Algorithm
are	O
likely	O
to	O
leak	O
and	O
this	O
makes	O
them	O
less	O
efficient	O
than	O
mechanical	O
linear	B-Algorithm
actuators	I-Algorithm
.	O
</s>
<s>
As	O
a	O
result	O
,	O
piezoelectric	O
actuators	B-Algorithm
can	O
achieve	O
extremely	O
fine	O
positioning	O
resolution	O
,	O
but	O
also	O
have	O
a	O
very	O
short	O
range	O
of	O
motion	O
.	O
</s>
<s>
Electro-mechanical	O
actuators	B-Algorithm
are	O
similar	O
to	O
mechanical	O
actuators	B-Algorithm
except	O
that	O
the	O
control	O
knob	O
or	O
handle	O
is	O
replaced	O
with	O
an	O
electric	O
motor	O
.	O
</s>
<s>
Rotary	B-Algorithm
motion	I-Algorithm
of	O
the	O
motor	O
is	O
converted	O
to	O
linear	O
displacement	O
.	O
</s>
<s>
Electromechanical	O
actuators	B-Algorithm
may	O
also	O
be	O
used	O
to	O
power	O
a	O
motor	O
that	O
converts	O
electrical	O
energy	O
into	O
mechanical	O
torque	B-General_Concept
.	O
</s>
<s>
There	O
are	O
many	O
designs	O
of	O
modern	O
linear	B-Algorithm
actuators	I-Algorithm
and	O
every	O
company	O
that	O
manufactures	O
them	O
tends	O
to	O
have	O
a	O
proprietary	O
method	O
.	O
</s>
<s>
The	O
following	O
is	O
a	O
generalized	O
description	O
of	O
a	O
very	O
simple	O
electro-mechanical	O
linear	B-Algorithm
actuator	I-Algorithm
.	O
</s>
<s>
Threaded	O
onto	O
the	O
lead	O
screw	O
is	O
a	O
lead	O
nut	O
or	O
ball	B-Algorithm
nut	I-Algorithm
with	O
corresponding	O
helical	O
threads	O
.	O
</s>
<s>
The	O
nut	O
is	O
prevented	O
from	O
rotating	O
with	O
the	O
lead	O
screw	O
(	O
typically	O
the	O
nut	O
interlocks	O
with	O
a	O
non-rotating	O
part	O
of	O
the	O
actuator	B-Algorithm
body	O
)	O
.	O
</s>
<s>
Most	O
current	O
actuators	B-Algorithm
are	O
built	O
for	O
high	O
speed	O
,	O
high	O
force	O
,	O
or	O
a	O
compromise	O
between	O
the	O
two	O
.	O
</s>
<s>
When	O
considering	O
an	O
actuator	B-Algorithm
for	O
a	O
particular	O
application	O
,	O
the	O
most	O
important	O
specifications	O
are	O
typically	O
travel	O
,	O
speed	O
,	O
force	O
,	O
accuracy	O
,	O
and	O
lifetime	O
.	O
</s>
<s>
There	O
are	O
many	O
types	O
of	O
motors	O
that	O
can	O
be	O
used	O
in	O
a	O
linear	B-Algorithm
actuator	I-Algorithm
system	O
.	O
</s>
<s>
It	O
all	O
depends	O
on	O
the	O
application	O
requirements	O
and	O
the	O
loads	O
the	O
actuator	B-Algorithm
is	O
designed	O
to	O
move	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
linear	B-Algorithm
actuator	I-Algorithm
using	O
an	O
integral	O
horsepower	O
AC	O
induction	O
motor	O
driving	O
a	O
lead	O
screw	O
can	O
be	O
used	O
to	O
operate	O
a	O
large	O
valve	O
in	O
a	O
refinery	O
.	O
</s>
<s>
For	O
electromechanical	O
linear	B-Algorithm
actuators	I-Algorithm
used	O
in	O
laboratory	O
instrumentation	O
robotics	O
,	O
optical	O
and	O
laser	O
equipment	O
,	O
or	O
X-Y	O
tables	O
,	O
fine	O
resolution	O
in	O
the	O
micron	O
range	O
and	O
high	O
accuracy	O
may	O
require	O
the	O
use	O
of	O
a	O
fractional	O
horsepower	O
stepper	B-Algorithm
motor	I-Algorithm
linear	B-Algorithm
actuator	I-Algorithm
with	O
a	O
fine	O
pitch	O
lead	O
screw	O
.	O
</s>
<s>
There	O
are	O
many	O
variations	O
in	O
the	O
electromechanical	O
linear	B-Algorithm
actuator	I-Algorithm
system	O
.	O
</s>
<s>
A	O
linear	B-Algorithm
actuator	I-Algorithm
using	O
standard	O
motors	O
will	O
commonly	O
have	O
the	O
motor	O
as	O
a	O
separate	O
cylinder	O
attached	O
to	O
the	O
side	O
of	O
the	O
actuator	B-Algorithm
,	O
either	O
parallel	O
with	O
the	O
actuator	B-Algorithm
or	O
perpendicular	O
to	O
the	O
actuator	B-Algorithm
.	O
</s>
<s>
The	O
motor	O
may	O
be	O
attached	O
to	O
the	O
end	O
of	O
the	O
actuator	B-Algorithm
.	O
</s>
<s>
The	O
drive	O
motor	O
is	O
of	O
typical	O
construction	O
with	O
a	O
solid	O
drive	O
shaft	O
that	O
is	O
geared	O
to	O
the	O
drive	O
nut	O
or	O
drive	O
screw	O
of	O
the	O
actuator	B-Algorithm
.	O
</s>
<s>
Compact	O
linear	B-Algorithm
actuators	I-Algorithm
use	O
specially	O
designed	O
motors	O
that	O
try	O
to	O
fit	O
the	O
motor	O
and	O
actuator	B-Algorithm
into	O
the	O
smallest	O
possible	O
shape	O
.	O
</s>
<s>
Similarly	O
the	O
motor	O
can	O
be	O
made	O
to	O
have	O
a	O
very	O
small	O
outside	O
diameter	O
,	O
but	O
instead	O
the	O
pole	O
faces	O
are	O
stretched	O
lengthwise	O
so	O
the	O
motor	O
can	O
still	O
have	O
very	O
high	O
torque	B-General_Concept
while	O
fitting	O
in	O
a	O
small	O
diameter	O
space	O
.	O
</s>
<s>
In	O
the	O
majority	O
of	O
linear	B-Algorithm
actuator	I-Algorithm
designs	O
,	O
the	O
basic	O
principle	O
of	O
operation	O
is	O
that	O
of	O
an	O
inclined	O
plane	O
.	O
</s>
<s>
Actuators	B-Algorithm
have	O
a	O
switch	O
to	O
reverse	O
the	O
polarity	O
of	O
the	O
motor	O
,	O
which	O
makes	O
the	O
actuator	B-Algorithm
change	O
its	O
motion	O
.	O
</s>
<s>
The	O
speed	O
and	O
force	O
of	O
an	O
actuator	B-Algorithm
depend	O
on	O
its	O
gearbox	O
.	O
</s>
<s>
The	O
amount	O
of	O
force	O
depends	O
on	O
the	O
actuator	B-Algorithm
’s	O
speed	O
.	O
</s>
<s>
One	O
of	O
the	O
basic	O
differences	O
between	O
actuators	B-Algorithm
is	O
their	O
stroke	O
,	O
which	O
is	O
defined	O
by	O
the	O
length	O
of	O
the	O
screw	O
and	O
shaft	O
.	O
</s>
<s>
The	O
mechanism	O
to	O
stop	O
the	O
stroke	O
of	O
an	O
actuator	B-Algorithm
is	O
a	O
limit	O
or	O
micro	O
switch	O
,	O
which	O
can	O
be	O
seen	O
in	O
the	O
image	O
below	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
large	O
engineering	O
movement	O
towards	O
actuator	B-Algorithm
miniaturization	O
.	O
</s>
<s>
Some	O
use	O
a	O
ball	B-Algorithm
screw	I-Algorithm
and	O
ball	B-Algorithm
nut	I-Algorithm
.	O
</s>
<s>
Gears	O
are	O
typically	O
used	O
to	O
allow	O
a	O
smaller	O
(	O
and	O
weaker	O
)	O
motor	O
spinning	O
at	O
a	O
higher	O
rpm	O
to	O
be	O
geared	O
down	O
to	O
provide	O
the	O
torque	B-General_Concept
necessary	O
to	O
spin	O
the	O
screw	O
under	O
a	O
heavier	O
load	O
than	O
the	O
motor	O
would	O
otherwise	O
be	O
capable	O
of	O
driving	O
directly	O
.	O
</s>
<s>
Effectively	O
this	O
sacrifices	O
actuator	B-Algorithm
speed	O
in	O
favor	O
of	O
increased	O
actuator	B-Algorithm
thrust	O
.	O
</s>
<s>
A	O
traveling-nut	O
linear	B-Algorithm
actuator	I-Algorithm
has	O
a	O
motor	O
that	O
stays	O
attached	O
to	O
one	O
end	O
of	O
the	O
lead	O
screw	O
(	O
perhaps	O
indirectly	O
through	O
a	O
gear	O
box	O
)	O
,	O
the	O
motor	O
spins	O
the	O
lead	O
screw	O
,	O
and	O
the	O
lead	O
nut	O
is	O
restrained	O
from	O
spinning	O
so	O
it	O
travels	O
up	O
and	O
down	O
the	O
lead	O
screw	O
.	O
</s>
<s>
A	O
traveling-screw	O
linear	B-Algorithm
actuator	I-Algorithm
has	O
a	O
lead	O
screw	O
that	O
passes	O
entirely	O
through	O
the	O
motor	O
.	O
</s>
<s>
In	O
a	O
traveling-screw	O
linear	B-Algorithm
actuator	I-Algorithm
,	O
the	O
motor	O
"	O
crawls	O
"	O
up	O
and	O
down	O
a	O
lead	O
screw	O
that	O
is	O
restrained	O
from	O
spinning	O
.	O
</s>
<s>
Linear	O
screw	O
actuators	B-Algorithm
can	O
have	O
a	O
static	O
loading	O
capacity	O
,	O
meaning	O
that	O
when	O
the	O
motor	O
stops	O
the	O
actuator	B-Algorithm
essentially	O
locks	O
in	O
place	O
and	O
can	O
support	O
a	O
load	O
that	O
is	O
either	O
pulling	O
or	O
pushing	O
on	O
the	O
actuator	B-Algorithm
.	O
</s>
<s>
The	O
braking	O
force	O
of	O
the	O
actuator	B-Algorithm
varies	O
with	O
the	O
angular	O
pitch	O
of	O
the	O
screw	O
threads	O
and	O
the	O
specific	O
design	O
of	O
the	O
threads	O
.	O
</s>
<s>
Acme	O
threads	O
have	O
a	O
very	O
high	O
static	O
load	O
capacity	O
,	O
while	O
ball	B-Algorithm
screws	I-Algorithm
have	O
an	O
extremely	O
low	O
load	O
capacity	O
and	O
can	O
be	O
nearly	O
free-floating	O
.	O
</s>
<s>
Generally	O
it	O
is	O
not	O
possible	O
to	O
vary	O
the	O
static	O
load	O
capacity	O
of	O
screw	O
actuators	B-Algorithm
without	O
additional	O
technology	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
high	O
viscosity	O
grease	O
can	O
be	O
added	O
to	O
linear	O
screw	O
actuators	B-Algorithm
to	O
increase	O
the	O
static	O
load	O
.	O
</s>
<s>
Static	O
load	O
capacity	O
can	O
be	O
added	O
to	O
a	O
linear	O
screw	O
actuator	B-Algorithm
using	O
an	O
electromagnetic	O
brake	O
system	O
,	O
which	O
applies	O
friction	O
to	O
the	O
spinning	O
drive	O
nut	O
.	O
</s>
<s>
When	O
the	O
actuator	B-Algorithm
needs	O
to	O
be	O
moved	O
,	O
an	O
electromagnet	O
counteracts	O
the	O
spring	O
and	O
releases	O
the	O
braking	O
force	O
on	O
the	O
drive	O
nut	O
.	O
</s>
<s>
Similarly	O
an	O
electromagnetic	O
ratchet	O
mechanism	O
can	O
be	O
used	O
with	O
a	O
linear	O
screw	O
actuator	B-Algorithm
so	O
that	O
the	O
drive	O
system	O
lifting	O
a	O
load	O
will	O
lock	O
in	O
position	O
when	O
power	O
to	O
the	O
actuator	B-Algorithm
is	O
turned	O
off	O
.	O
</s>
<s>
To	O
lower	O
the	O
actuator	B-Algorithm
,	O
an	O
electromagnet	O
is	O
used	O
to	O
counteract	O
the	O
spring	O
force	O
and	O
unlock	O
the	O
ratchet	O
.	O
</s>
<s>
Dynamic	O
load	O
capacity	O
is	O
typically	O
referred	O
to	O
as	O
the	O
amount	O
of	O
force	O
the	O
linear	B-Algorithm
actuator	I-Algorithm
is	O
capable	O
of	O
providing	O
during	O
operation	O
.	O
</s>
<s>
Dynamic	O
load	O
is	O
the	O
figure	O
which	O
most	O
actuators	B-Algorithm
are	O
classified	O
by	O
,	O
and	O
is	O
a	O
good	O
indication	O
of	O
what	O
applications	O
it	O
would	O
suit	O
best	O
.	O
</s>
<s>
In	O
most	O
cases	O
when	O
using	O
an	O
electro-mechanical	O
actuator	B-Algorithm
,	O
it	O
is	O
preferred	O
to	O
have	O
some	O
type	O
of	O
speed	O
control	O
.	O
</s>
<s>
Some	O
actuators	B-Algorithm
are	O
available	O
with	O
several	O
different	O
gearing	O
options	O
.	O
</s>
<s>
The	O
duty	O
cycle	O
of	O
a	O
motor	O
refers	O
to	O
the	O
amount	O
of	O
time	O
the	O
actuator	B-Algorithm
can	O
be	O
run	O
before	O
it	O
needs	O
to	O
cool	O
down	O
.	O
</s>
<s>
Staying	O
within	O
this	O
guideline	O
when	O
operating	O
an	O
actuator	B-Algorithm
is	O
key	O
to	O
its	O
longevity	O
and	O
performance	O
.	O
</s>
<s>
Where	O
a	O
rotary	O
motor	O
would	O
spin	O
around	O
and	O
re-use	O
the	O
same	O
magnetic	O
pole	O
faces	O
again	O
,	O
the	O
magnetic	O
field	O
structures	O
of	O
a	O
linear	O
motor	O
are	O
physically	O
repeated	O
across	O
the	O
length	O
of	O
the	O
actuator	B-Algorithm
.	O
</s>
<s>
Since	O
the	O
motor	O
moves	O
in	O
a	O
linear	O
fashion	O
,	O
no	O
lead	O
screw	O
is	O
needed	O
to	O
convert	O
rotary	B-Algorithm
motion	I-Algorithm
to	O
linear	O
.	O
</s>
<s>
Most	O
linear	O
motors	O
have	O
a	O
low	O
load	O
capacity	O
compared	O
to	O
other	O
types	O
of	O
linear	B-Algorithm
actuators	I-Algorithm
.	O
</s>
<s>
Telescoping	O
linear	B-Algorithm
actuators	I-Algorithm
are	O
specialized	O
linear	B-Algorithm
actuators	I-Algorithm
used	O
where	O
space	O
restrictions	O
exist	O
.	O
</s>
<s>
Other	O
more	O
specialized	O
telescoping	O
actuators	B-Algorithm
use	O
actuating	O
members	O
that	O
act	O
as	O
rigid	O
linear	O
shafts	O
when	O
extended	O
,	O
but	O
break	O
that	O
line	O
by	O
folding	O
,	O
separating	O
into	O
pieces	O
and/or	O
uncoiling	O
when	O
retracted	O
.	O
</s>
<s>
Examples	O
of	O
telescoping	O
linear	B-Algorithm
actuators	I-Algorithm
include	O
:	O
</s>
<s>
Actuator	B-Algorithm
Type	O
Advantages	O
Disadvantages	O
Mechanical	O
Cheap	O
.	O
</s>
<s>
Self-contained.Identical	O
behaviour	O
extending	O
or	O
retracting.DC	O
or	O
stepping	B-Algorithm
motors	I-Algorithm
.	O
</s>
<s>
Precise	O
position	O
control	O
impossible	O
except	O
at	O
full	O
stops	O
Wax	B-Algorithm
motor	I-Algorithm
Smooth	O
operation	O
.	O
</s>
<s>
Segmented	O
spindle	O
Very	O
compact.Range	O
of	O
motion	O
greater	O
than	O
length	O
of	O
actuator	B-Algorithm
.	O
</s>
<s>
Both	O
linear	O
and	O
rotary	B-Algorithm
motion	I-Algorithm
.	O
</s>
<s>
MICA	O
:	O
Moving	O
ironcontrollable	O
actuator	B-Algorithm
High	O
force	O
and	O
controllable.Higher	O
force	O
and	O
less	O
losses	O
than	O
moving	O
coils.Losses	O
easy	O
to	O
dissipate.Electronic	O
driver	O
easy	O
to	O
design	O
and	O
set	O
up	O
.	O
</s>
