Product details
Behind every vent drive is a rack and pinion, and the LV7 and LV20 are the two strengths we use. Both are aluminium, straight (R) or curved (B), and the choice between them starts with the opening you need to cover. LV7 is for standard aluminium glasshouses where the measured distance from ridge to the end of the opening is up to 150 cm, and LV20 is for anything longer and for heavier structures such as entrances and superstructures.
Recommended working loads follow the type: LV7 straight 50 kg, LV7 curved 25 kg, LV20 straight 75 kg and LV20 curved 40 kg. Curved racks are for limited space below the ridge, for instance in small houses or where screens run close to the top. Straight racks cover everything else. LV20 straight racks also come in lengths up to 450 cm, but the 300 cm and longer racks are for pulling screens only and cannot be used on windows.
The build is designed for longevity. The rack is a hard aluminium alloy with a softer zinc pinion, fitted with synthetic rollers that keep friction low. Teeth sit close to the drive shaft, which lowers the torque the motor must supply and reduces twisting of the shaft, so smaller gear motors can often be used. Mounting points use solid aluminium inserts so the hole keeps its shape, and the housing keeps dirt out. Greasing once a year is the minimum maintenance.
Getting the number of racks right is a calculation, not a guess: racks sit no more than 2 m apart, and roof pitches under 25 degrees need a shorter rack or a rack stop. We do that sizing, then specify the matching drive from our DGT vent motors. Sitetech supplies and installs the full vent system as main UK distributor for DGT by Senmatic.
Key capabilities
- LV7 (normal strength) and LV20 (extra strong) versions
- Straight (R) and curved (B) racks
- Hard aluminium alloy rack with zinc pinion
- Synthetic rollers and bearings in the pinion for low friction and noise
- Solid aluminium mounting points keep the hole round
- Teeth placed close to the drive shaft to reduce torque demand
- Closed housing and factory-lubricated pinion for minimal maintenance
- Many lengths, supplied complete, without t-bracket or as rack only
- Rack stop available for shallow roof pitches
Technical specifications
| LV7R (straight) recommended load | 50 kg |
|---|---|
| LV7B (curved) recommended load | 25 kg |
| LV20R (straight) recommended load | 75 kg |
| LV20B (curved) recommended load | 40 kg |
| LV7 recommended max. opening length | 150 cm (165 cm for certain special constructions) |
| LV7R straight lengths | 60 – 165 cm (50 cm rack only) |
| LV7B curved lengths | 75 – 165 cm |
| LV20R straight lengths (windows) | 65 – 250 cm |
| LV20R straight lengths (screens only) | 300 – 450 cm |
| LV20B curved lengths | 65 – 160 cm |
| Length tolerance | +/- 5 cm |
| Rack spacing | Max. 2 m between racks |
| Pinion item numbers | LV7R 840070, LV7B 840080, LV20 (straight and curved) 840200 |
| Material | Hard aluminium alloy rack, zinc pinion |
| Minimum maintenance | Grease rack at least once a year |
