Accurate dosing of grease and oil

Gas springs are lubricated automatically with DOPAG dosing systems

For several decades, STABILUS gas springs and dampers have been well known for their successful use in the automobile and furniture industries, providing a practical design element in more than 300 different applications, wherever assistance in lifting, lowering, moving or adjusting is needed. Applications in industries other than automotive (where they are used for trunk, tailgate, door and hood opening, as well as providing comfort and safety in seat adjustment applications) have evolved and STABILUS hydropneumatic gas springs can now be found in such diverse products as hospital beds, operating theatre tables, roof windows and office seating. Located in Koblenz in Germany, the company is a leading worldwide manufacturer of gas springs, producing 120 million units annually, each and every one of which must be lubricated with accurate and repeatable volumes of grease or oil, depending on the location within the gas spring assembly.

DOPAG dispensing valves in use
During the assembly process the gas springs, which have been loaded onto a rotary table, firstly require a small pre-determined volume of grease to be automatically applied to the piston rods. This is achieved at the first lubricating station by means of DOPAG needle type metering valves, each capable of accurately metering volumes between 0.001 and 3.0 ml with each shot. At the second lubricating station, tiny drops of oil are metered onto the double lip seals in the cylinders in order to minimise friction, using DOPAG chamber type metering valves.

This type of metering valve is particularly useful for such applications as they feature a snuff-back facility. This characteristic avoids the possibility of unwanted drips of oil contaminating other parts or components following the conclusion of the metering process. Finally, at a third station, a predetermined volume of oil is metered into the cylinders using a flowmeter system controlled by MR20 metering controllers before the cylinders are charged with nitrogen. The entire lubrication cycle is thus completed automatically, thanks to DOPAG advanced metering technology.