The Lever arm is the distance between the pivot point of the sash (hinge) and the point where the actuator acts. The larger the lever arm, the less force the actuator needs – but the more stroke is required for the same opening width.
The principle
- Actuator far from the pivot: little force, a lot of stroke
- Actuator close to the pivot: a lot of force, little stroke
- that is why the actuator usually sits on the edge opposite the hinges
Example
A bottom-hung window is 1 m high. If the actuator sits at the top edge, the full lever arm of 1 m applies. If it sat at half height, it would need about twice the force for the same load.
Frequently asked questions
Where should the actuator be positioned?
As a rule, centrally on the edge opposite the hinges. The exact position is given in the actuator installation instructions.
How does this relate to the opening width?
Stroke and lever arm together determine how far the sash opens. More in the glossary under opening width.
Read more
Not sure which actuator fits? Call us at 040 50694631 (Mon–Fri 8 am–5 pm) or use the actuator finder.
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Datasheets and manuals · All terms in the glossary
