Dynamic metering devices

On SKF MonoFlex single-line metering devices designed as dynamic metering devices, the quantity of lubricant is fed to the lubrication point while pressure is being built up in the main line, i.e., during the lubrication unit’s run time. On dynamic metering devices, the expelling pressure can be set approximately equal to the maximum permissible pressure of the pressure regulating valve on the lubrication unit.

After the lubrication unit is switched on, the lubricant is drawn out of the lubricant reservoir by the lubricant pump and fed through the main line to the dynamic metering devices via the pressure relief valve and the pressure regulating valve. The unit’s principle of operation requires that pressure be built up in the main line within a period < 1 s, i.e., pressure build-up in the main line must be sudden (dynamic). The pressure build-up dynamically in the centralized lubrication system causes the metering piston to move toward the check valve (fig.2), expelling the lubricant (fig.1) that is upstream of the metering piston. The check valve opens and the lubricant is expelled in the direction of the lubrication point until the lower valve seat closes. The lubricant continues to be fed toward the lubrication point until the check valve closes again.

After the lubrication unit is turned off, pressure in the centralized lubrication system is relieved. In this process, the metering piston under spring preload returns to its normal position. At the same time, the lubricant is moved through the annular gap between the metering piston and piston chamber. The upper check valve prevents the lubricant from flowing back into the metering chamber from the lubrication point line. The dynamic metering device is ready for the next lubrication cycle (fig.3).


Applications:
  • chains in machinery and conveyor belts
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