Cut Sheet

V8-T2-2 Volume 8—Sensing Solutions CA08100010E—August 2015 www.eaton.com
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2.0
Limit Switches
Introduction
Technical Reference
Limit Switches
Mechanical Limit Switches
are contact sensors widely
used for detecting the
presence or position of
objects in industrial
applications.
Limit Switches offer high
precision in terms of accuracy
and repeatability. This is
primarily due to the fact that
they make direct contact
with the target. When an
object contacts the limit
switch lever (or plunger)
the lever moves a pre-travel
distance to the operating
point where the contacts are
tripped. Movement of the
lever beyond this point is
called the over-travel.
Lever Type Actuator
Refer to Sensor Learning Course, Page V8-T12-4, for a
complete description of limit switch terminology.
Differential
Reset Point
Initial Position
Operating
Point
Pre-travel
Over-travel
Initial Position
Over-travel
Reset Point
Operating Point
Pre-travel
Final Position
Differential
Limit switches contain the
following major components.
These may be modular or part
of a single-piece switch.
Limit Switch Components
Actuator
This is the part of the switch
that contacts the target.
Typical actuators are levers
and plungers. Several styles
are available, see Sensor
Learning Course, Page
V8-T12-4, for more
information.
Switch Body
This part contains the
electrical contact mechanism.
For complete information on
electrical outputs, see Sensor
Learning Course, Page
V8-T12-4.
Terminals
The terminals are the point of
connection for the wiring.
These terminals may be on
the body itself, or housed in a
removable receptacle. The
limit switch may also come
equipped with a factory
installed cable or pin-
connector.
Actuator/
Operating
Head
Switch
Body
Switch
Body
Actuator/
Operating
Head
Receptacle/
Terminals