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Lead Contents

Safety Limit Switch: Total Travel (TT)

FAQ No. FAQ02421

Primary Contents

Question

What is total travel (TT)?

Answer

Refer to the following table of terms for operating characteristics.

Operating Status
FeatureTermAbbreviationUnitDefinition
ForceOperating
Force
OFN, NmThe force needed to be applied to the Actuator to move from the free position to the operating position.
Direct
Opening
Force
DOF
(See note 2.)
N, NmThe force needed to be applied to the Actuator to move from the operating position to the direct opening position.
Total
Travel
Force
TTFN, NmThe force needed to be applied to the Actuator to move from the free position to the total travel position.
TravelPretravelPTmm, °The travel distance or angle from the free position to the travel position of the Actuator.
Direct
Opening
Travel
DOT
(See note 2.)
mm, °The travel distance or angle from the free position to the direct opening position of the Actuator.
Total
Travel
TTmm, °The travel distance or angle of the Actuator from the free position to the total travel position.
PositionFree
Position
FPmm, °The Actuator position when no external force is applied.
Operating
Position
OP
(See note 1.)
mm, °The position where the moving contact starts to open or close when an external force is applied to the Actuator.
Direct
Opening
Position
DOP
(See note 2.)
mm, °The Actuator position when the moving contacts are directly open when an external force is applied to the Actuator.
Total
Travel
Position
TTPmm, °The Actuator position when the Actuator has reached the stopper.

Note 1:
For slow-operating safety switches, the operating position (OP) and return position (RP) are almost identical.

Note 2:
The DOF, DOT, and DOP values were specified to ensure that the direct opening mechanism (forcibly opened contacts) functions correctly.