Stroke
The required opening width of the window can be calculated based on the specification of a desired opening cross section or opening angle and based on the window dimensions of sash height / width. Depending on the type of drive and type of installation selected, this opening width will be equivalent to the drive stroke. The opening width that can be achieved with scissor drives and spindle drives that are installed on the side depends on the drive stroke and installation measure x. It is, thus, definitely possible to achieve large opening widths with small drive strokes.

Compressive force / tractive force
The compressive / tractive force indicates the force of the drive that is available to open and close the window. The drive must be selected such that the specified drive force is greater than the required force that results from the sash weight and any wind / snow loads that may have to be considered.

F_Drive ≥ F_req = F_G + F_W + F_S

F_Drive: Force generated by the drive
F_req: required force
F_G: Weight force of the sash
F_W: Wind force
F_S: Snow force

The weight force F_G is calculated by multiplying mass with gravitational acceleration. The calculation uses the simplified formula given below

F_G [N] = sash weight [kg] x 10 [m/s²]

Simply put, we can deduce that: 10 kg ~ 100 N

The wind / snow force is calculated by multiplying the wind / snow load [N/m²] by the area on which the load acts vertically. One factor that needs to taken into account is the installation position of the window. For instance, the wind force generated at a facade window is markedly higher because the entire area of the window is subjected to the wind load as an attack surface. The attack surface in roof-top windows is the projection surface of the window that is situated vertically to the wind load. This surface becomes smaller with a reduction in roof pitch.