Greenhouses are getting bigger all the time. This means that the requirement of optimum ventilation will increase proportionally. A good ventilation or air tightness is important for an even greenhouse climate, AND increases the grower's options. For years, Snelder has been delivering vent opening mechanisms for all common greenhouses. Through a program developed in cooperation with TNO, we are able to calculate the vent opening mechanisms. In this way you will be sure that our push rods guarantee a hermetic seal of all vents. Our fully automatically produced aluminium or steel push rods always comply with the applicable standard (NEN 3859) for greenhouse construction.
Due to the slope in the greenhouse and the longer chains of windows, the vents have the tendency to lie at one side. As a result, the push rods in the collection point in the clamp also slide to one side. This leads to torsion on the push-pull tube and an additional load for the gear-racks. In order to tackle this problem, Snelder developed the stabilizing AK block. By using an extra wide aluminium clamp, this block is mounted between the push rods and thus supplies the required stability. Distortion of the push-pull tube and unnecessary wear of the gear-racks and drive are prevented in this way.
Snelder guarantees that the drive shafts for ventilation systems will have a constant quality. The shafts are welded fully automatically, whereby various types of chainwheels as well as weld/slide couplings are used. Snelder supplies complete ventilation systems, including motor reductors and accessories from various manufacturers.
Due to the slope in the greenhouse and the longer chains of windows, the vents have the tendency to lie at one side. As a result, the push rods in the collection point in the clamp also slide to one side. This leads to torsion on the push-pull tube and an additional load for the gear-racks. In order to tackle this problem, Snelder developed the stabilizing AK block. By using an extra wide aluminium clamp, this block is mounted between the push rods and thus supplies the required stability. Distortion of the push-pull tube and unnecessary wear of the gear-racks and drive are prevented in this way.
Snelder guarantees that the drive shafts for ventilation systems will have a constant quality. The shafts are welded fully automatically, whereby various types of chainwheels as well as weld/slide couplings are used. Snelder supplies complete ventilation systems, including motor reductors and accessories from various manufacturers.
Types: Ventilation
- End gable ventilation
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In end gable ventilation, the lattice girder is missing, as a result of which the push rods have to be supported in another way.The solution is a floating C girder which is attached to the gutter by means of a short post.Snelder has special, compact rail mechanism housings that are mounted in the C girder.This construction is very compact and does not take away much light from the greenhouse.
- Truss-rail ventilation
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In the so-called Venlo greenhouses, truss-rail ventilation is the system that is most commonly used at this moment.Here, a moving push-pull tube is used, which is connected to the vents by means of push rods.For this truss-rail system we supply rail mechanism housings and self-lubricating diabolo rolls for various truss sizes.The rail mechanism housing clamped around the lattice guarantees a stable guidance of the galvanized push-pull tube.
- Double continuous ventilation
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In this type of rail mechanism, two push-pull tubes are placed above each other on the truss.Each tube operates one of the continuous vents that are placed opposite each other.In this system, the push rods are running very close along each other, and therefore their measurements must be very accurate.For this, Snelder uses 3D simulation.This allows us to see quickly and accurately, if the covering windows are running free. For optimum stability, the push rods are mounted to the push-pull tube with an AK-stabilizer and a heavy aluminium clamp.
- Swing ventilation
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The swing ventilation system is one of the oldest systems.The principle of this system is that the vents are not above the truss, as in the rail vent system, but in the centre of a section.The vents are opened by means of ridge push rods, window push rods and a swing tube mounted to the push/pull rods.That is the tube that makes a swinging movement when opening and closing.
This system allows some tolerance for the glazing, as the swing tube compensates any alignment differences of the vents.
- Cabrio ventilation
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In this type of ventilation system, two covering halves can also be opened independently of each other, and both push-pull tubes are placed above each other.In case of cabrio ventilation, however, the windows close in the ridge.This is contrary to normal ventilation, which hinges in the ridge. For good stability, the push rods in this type of ventilation are usually made of galvanized steel.
The drive for cabrio ventilation is the same as for double continuous ventilation, including the DDL rail mechanisms and AK-stabilizer.