• The Coroma Jack Knife Door is the most rigid Door on the market.
• Doors balance in all positions and require practically no maintenance.
• Doors are manufactured up to 8 metres wide and 5 metres high and are operated manually with ease.
• Doors cause no horizontal stresses to buildings.
• The doors are easily glazed to provide good interior light and maximum safety.

The Jack-Knife door is made up of one panel, horizontally split and hinged into two equal leaves for the non-protruding door or the 1/3 x 2/3 split for the protruding canopy type door. The bottom leaf has side rollers running in vertical channel guides. Each roller has an independent cable attached to it, which runs through cable sheaves to the single counter-weight. The counter-weight tower is mounted on the inside of the opening against the wall next to the door. Smaller doors are hand operated. Larger doors, as an added feature, may be hand crank operated.

Factories, warehouses and petrol stations

Advantages

1. Outward opening access and panic doors can be included into the frame of the Jack-knife door
2. Robust reliable door
3. The top section is suitable for glazing for extra light
4. Practically no maintenance required
5. Easily operated with a pull stick - larger doors preferably crank operated
6. Door cladding can be matched to roof sheeting 
7. No horizontal stresses to building
8. Can be insulated for wine cellars

Disadvantages

1. Not suitable for motorisation
2. Affected by wind during operation
3. Protruding section of the Jack-knife door is susceptible to vehicle damage when open