Various Types of Net Closures

Completely or partially closed hail net systems:

Model 1: Front side curtain without a cantilever prop (with a fixed headroom)

A steel wire with a diameter of 3.8 mm is placed and tightened in the net connection of the front row. On this a net panel in the required width is sewn or needled. The net panel is tightened towards the anchor with the support of a ring of the Wiesel net connection and a hook that is assembled at the net connection wire.

Model 2: Flexible front side curtain without a cantilever prop

At the lower net edge a steel rope is sewn into or needled causing a smooth descent of the net curtain when closed. A PVC-protected steel bar allows a gentle glide from the ridge to the anchor. By means of special fantails assembled on the ridge, a taut wire and a lifting rope assembled on it, a counterweight and a special rail with carriages at the end of the taut wire, as well as a crank handle, or an electric wire rope winch (12 V or 220 V), the net panel can be moved up or down just like a curtain.

Feature: No trees must be between front side column and anchor which could possibly interfere with the gliding procedure.

Model 3: Front side curtain with a cantilever prop and fixed headroom

Through the assembly of the special distance tubes the protection space will be extented over the front side columns towards the anchor.

The assembly of the net curtain is the same as for model 1.

Feature: There can be trees between the front side column and the anchor and they are well protected.

Model 4: Flexible front side curtain with a cantilever prop

Through the assembly of the special distance tubes the protection space is enlarged, as can be seen at point 3, and the gliding bar for the curtain is brought into an almost vertical position. The fantails for the front side lifting and the bar fitting are not fixed at the Firstfix net connection but at the end of the cantilever props. All the other elements are the same as for model 2.

Feature: Trees between the front side column and the anchor are possible. However, only branches and twigs can stand towards the gliding bar.

Model 5: Fully automated front side curtain

Springeth in Voghiera

The project has an entire area of 22 hectares and is characterised by a bulky row completion, curves, transversal pieces and various entry points.

About 400 front side units are opened and closed by means of a 12 V engine installed in the centre of the plant which uses a specifically designed central fairlead technology. The remaining angular recesses around the block of the building are also supplied by a 220 V engine. Both engines are operated via remote control.

Due to this technology it is possible to effectively achieve a 100 % hail and sun protection and a protection against birds and insects (i.e., the European corn borer). The basic idea of the front side curtain, however, is for frost protection by icing the nets, the water consumption of which is extremely low in comparison.

As far as this current project is concerned, the installation of a huge water reservoir can be spared; thus, the front side curtain technology can be financed with this saving. One of the most important lessons learned is, that seen from the technical point of view, the most bulky plants can also be functionally equipped.

Model 6: Cage system

The cage system allows full closure of the machine track and the roofing with the hail netting.

The hail net is entirely tightened down to the ground, both outside the edge rows and at the front side columns outside the machine track.

For entry and exit a gate should be installed. There are advantages such as for models 2, 4 and 5, but the cage system is more efficient since during operation, for instance for mulching, fertilising etc. the gate can be closed.

For models 2 and 4 wind, birds and insects can enter into the plant during the work mentioned above.

Please note: Cage models cannot be installed everywhere, i.e., if there is a joint turn-around space with the adjacent neighbour’s land.

Model 7: Lan-Man 2007

The net is held at the front rope and rolled in towards the middle of the track. It is then folded twice over the 10 cm long sleeve and tied in place.

The required width of the front net (running crosswise) is sewed or pinned to the cross wire of the front row of pillars.