System description : Dualline Systems

System description : Dualline Systems


Centralised lubrication systems with two main feed lines are chiefly used for the lubrication of machines and plant with a large numbers of lubrication points:

lubrication points: up to 1000
pipe lenght: up to 150 m
pump pressure: up to 400 bar

Example of application

Smelting plant, rolling mills, mining power stations, cement works, sugar refineries, breweries, construction machinery, etc.


The lubrication system consists principally of the pump, one 4/2-way or two 3/2-way change-over valves, the two main feed lines, the distributors arranged close to the lubrication points, the lines leading to the lubrication points, witchgear at the line end, the pressure gauge unit and the controls. A pressure relief valve is required to protect the pump from over pressure.

Mode of operation

The delivery side of a lubrication pump and the lubricant tank for the pump are connected alternately, via a change-over device (a 4/2-way valve) to each of the main feed lines. As many main distributors as required can be connected to the two main feed lines. The lubricant pressure causes half the lubrication points conected to the distributors to be supplied with a quantity of lubricant depending on the volume swept by the plunger. The change-over operation is then initiated either manually or automatically; this causes the main feed line which had been under pressure to be connected to the pump tand and the previously unpressurised main feed line to be connected to the pump delivery, whereupon lubricant is supplied to the other half of the lubrication points. There then generally follows an interval in the lubrication process.

Outstanding features

  • Metering can be adjusted to meet the requirements of the individual lubrication points
    • by selection of the appropriate distributor size,
    • by varying the metering setting and
    • by varying the interval.
  • The metered quantity is independent of back pressure.
  • The systems can at any time be extended by connection of additional distributors, or reduced by shutting down distributors
    or outlets.
  • Special monitoring of critical lubrication points is made possible for each pair of distributor outlets using limit switches.
  • The system can be operated fully automatically with variable intervals.
  • Up to over 1,000 lubrication points at a distance of 100 metres can be lubricated, depending on the type of pump
    and lubricant.
  • In all automatic systems, the patented switchgear SG - A, which initiates change-over, that is, the pressure change in the two main feed lines, as a function of the differential pressure at the line end, is used. Depending on temperature, lubricant and line dimensions, the optimum working pressure is adjusted automatically and there are, in comparison to systems where the switchgear is provided on the pump, the following advantages:
    • Pump load kept to a minimum.
    • Event at low temperature, which causes a slow pressure build-up (pipe friction), delivery of the correct quantity
      of lubricant is ensured by the switchgear SG - A being installed at the line end.
    • Additional monitoring of the main feed lines by means of the switchgear.

Related documents

System description - Dualline-Systems (PDF File)

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