Technical Guide for Limit Switches
•
Unbalanced force must not be imposed on the actuator. Otherwise,
wear and tear on the actuator may result.
•
With a roller actuator, the dog must touch the actuator at a right
angle. The actuator or shaft may deform or break if the dog touches
the actuator (roller) at an oblique angle.
•
Make sure that the actuator does not exceed the OT (overtravel)
range, otherwise the Limit Switch may malfunction. When mounting
the Limit Switch, be sure to adjust the Limit Switch carefully while
considering the whole movement of the actuator.
•
The Limit Switch may soon malfunction if the OT is excessive.
Therefore, adjustments and careful consideration of the position of
the Limit Switch and the expected OT of the operating body are
necessary when mounting the Limit Switch.
•
When using a pin-plunger actuator, make sure that the stroke of the
actuator and the movement of the dog are located along a single
straight line.
•
Be sure to use the Limit Switch according to the characteristics of
the actuator.
If a roller arm lever actuator is used, do not attempt to actuate the
Limit Switch in the direction shown below.
•
Do not modify the actuator to change the OP.
•
With the long actuator of an Adjustable Roller Lever Switch, the
following countermeasures against lever shaking are
recommended.
1.Make the rear edge of the dog smooth with an angle of 15
°
to 30
°
or make it in the shape of a quadratic curve.
2.Design the circuit so that no error signal will be generated.
3.Use a switch that is actuated in one direction only. (Alternatively,
set the Switch so that it is operated only in one direction.)
•
With a bevel plunger actuator, make sure that the width of the dog
is wider than that of the plunger.
Incorrect
Correct
Roller
Roller
Dog
Dog
Correct
Incorrect
Dog
Dog
Operating
body
Install a stopper.
PT (Pretravel)
FP (Free position)
OP (Operating position)
OT (Overtravel)
TTP (Total travel position)
Reference line
70% of
rated OT
100% of
rated OT
Distance to the
optimum setting range.
Optimum setting range
Correct
Stopper
Incorrect
Correct
Operating
body
Operating
body
Incorrect
Incorrect
Correct
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