TwinVenlo mechanism: the mechanism for continuous vents on Venlo greenhouses

Do you grow plants in a Venlo greenhouse? Do you need a large amount of ventilation capacity? Are you considering building such a greenhouse? Then the new TwinVenlo rail mechanism from Van der Valk Horti Systems is certainly worth looking at. The system is distinctive due to its two pull-push tubes positioned one atop the other and push rod sets that interweave.

TwinVenlo mechanism

The TwinVenlo rail mechanism has an unique structure, in which the pull-push tubes (for independent control of the two halves of the roof) are installed not next to each other but atop each other. This allows the two sets of push rods (for the upper and lower pull-push tubes) to interweave, and the screen can fit easily against the truss. The pull-push tubes of the TwinVenlo pass through 2 holes positioned above each other in the posts.
To ensure the required stability, the TwinVenlo rail mechanism incorporates the Stabimax® vent-opening mechanism and the Valk-Plus® window push rods, two important innovations from Van der Valk Horti Systems that are already being used around the world. The Stabimax® system consists of a hinge element that with its cunning form holds the push rods in an iron grip. Plus a unique clamp that is wide enough to easily absorb the tolerances of your greenhouse and is absolutely torsion-free. The Valk-Plus® push rods are made exactly to measure to your specifications according to a new and completely automated production process. They are treated in several unique ways to make them distinctive for their functionality and ease of mounting.

Calculation tools and certification


In partnership with TNO (the independent research agency in the Netherlands), the WinTop calculation programme was developed.

Based on a range of variables (the geometry of the roof, the maximum local wind load, the desired opening angle, etc.), it can calculate all of the influential factors affecting the reliability of the system, like the required structural strength, clearance of the mechanism with regard to the roof structure, and the position of the rail brackets and the gear racks.

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Van der Valk Horti Systems

Zwartendijk 73
The Netherlands

Phone +31 (0)174 - 21 22 23
Fax +31 (0)174 - 24 27 27