Northern Polytunnels

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01282 873120
Sales & Enquiries
01282 873120

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Polytunnel Ventilation Chain Pulley Gearbox

Hand-operated geared pulley/winch with integrated roller-guide carriage. The ‘endless chain’ design makes it ideal for operating vents which are too high to operate with a crank handle gearbox. A 6m galvanised chain provides a 2.8-3.0m loop, making it suitable for screens up to 4m high. Torque: 40Nm Speed Ratio: 5:1

Availability: 4 to 5 days

£69.00 (Exc. VAT) £82.80 (Inc. VAT)
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Product Description

The ‘endless chain’ design makes it ideal for operating vents which are too high to operate with a crank handle gearbox. A 6m galvanised chain provides a 2.8-3.0m loop, making it suitable for screens up to 4m high. Ideal for operating the end vents on Spanish tunnels (strawberry polytunnels). Can be retrofitted to most existing polytunnel ventilation systems.



A clutch inside the gearbox holds the drive tube at any position between fully open and fully closed. It comes complete with a roller-guide carriage which allows it to run up and down a vertical 25mm O.D. guide tube (guide tubes available on request).
Can operate up to 90m of vent, depending on the weight (i.e. the height of the screen and the diameter of the drive tube).
The diameter of the drive shaft is ????, so it would ideally take a 32mm O.D. steel drive tube. Drive tube and polythene clips also available (phone for details). We recommend using a polythene clip every 20cm-30cm along the drive tube.


Torque: 40Nm
Speed Ratio: 5:1


Easy to install and operate.

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Mill Green, Waterside Road, Colne, Lancs, BB8 0TA