3. Overview/functional description
3.5.1 Functioning of a VPK progressive metering device
The task of the progressive metering device
is to consecutively distribute specified por-
tions of the pressure-fed lubricant (grease
or oil) to the connected lubrication points.
The lubricant continues to discharge as
long as it is pressure-fed to the progressive
metering device. The specified portions are
generated through the piston movement.
Two lubricant outlets on the two end posi-
tions of the piston travel are allocated to
each piston.
The number of pistons within a progressive
metering device is variable from 3-10. If
lubricant is pressure-fed, the pistons of a
progressive metering device move sequen-
tially to their end position. The piston move-
ment displaces the lubricant upstream of
the piston towards the downstream outlet.
The piston movement can only start if the
upstream piston has reached its end posi-
tion. If all pistons are in their left or right end
position, internal connecting bores in the
progressive metering device ensure that the
pistons continue running reliably as defined.
If all pistons have moved once to the left
end position as well as to the right end posi-
tion, all connected lubrication points have
been supplied once with the preset lubricant
quantity.
The portions for both outlets are deter-
mined by the diameter and the distance
traveled by the piston.
The selection of the required portion is
made during the design of the progressive
metering device. A subsequent change of
the portions is only possible through modi-
fication of the progressive metering device
/ replacement of the progressive metering
device section.
Information on the design
The general criteria for the design of pro-
gressive metering devices also apply without
restrictions to the sectional progressive
metering devices. The most important crite-
rion is the number of cycles (stroke rate). It
should be kept as low as possible by select-
ing sections with a sufficiently high volume.
A maximum value of 200 cycles/min should
not be exceeded.
This also reduces pressure losses and noise
levels. In case of an installation on moving
machine parts or in case of strong vibra-
tions (e.g. on pressing machines), the piston
position of the progressive metering device
should not correspond with the direction of
movement of the machine part.
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951-230-008-EN
Version 04
EN
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