What is direct opening force (DOF)?

Refer to the following table of terms for operating characteristics.

Operating Status
Classification Term Abbreviation Unit Definition
Force Operating
Force
OF N, Nm The 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, Nm The force needed to be applied to the Actuator to move from the operating position to the direct opening position.
Total
Travel
Force
TTF N, Nm The force needed to be applied to the Actuator to move from the free position to the total travel position.
Travel Pretravel PT mm, ° 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
TT mm, ° The travel distance or angle of the Actuator from the free position to the total travel position.
Position Free
Position
FP mm, ° 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.
Total
Travel
Position
TTP mm, ° 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 are specified to ensure that the direct opening mechanism (forcibly opened contacts) functions correctly. 


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